Psy

Text: Psychology Core Concepts: Zimbardo, Johnson and Hamilton 7
TH EDITION (978-0-205183463) I cant found the text online maybe you can

Or You can access The Discovering Psychology video series on the internet for free!

Go to www.learner.org
Click on the blue tab near the top that reads “view programs”
Many film series will be listed. They are in alphabetical order. Scroll down to Discovering Psychology: Updated Edition. Click on it.
All 26 episodes from the series are listed in order. Double click on the box that says “VoD” next to the episode you wish to view. That’s it!

Type 1 page for each ½ hour video unit where you submit bullets outlining the content of each ½ hour lecture (not more than one page in length) AND, SEPARATELY, ANSWER ALL LEARNING OBJECTIVE QUESTIONS FROM THE ATTACHED/ENCLOSED PACKET( state each question before each of your responses. Make sure you cite page references from the text for each of your answers).

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Objectives 1

After viewing the television program and completing the assigned readings, you should be able to:

1. Define Psychology.

2. Distinguish between the micro, molecular, and macro levels of analysis.

3. Describe the major goals of psychology.

4. Describe what psychologists do and give some examples of the kinds of questions they may be interested in investigating.

5. Summarize the history of the major theoretical approaches to psychology.

6. Describe seven current psychological perspectives.

7. Describe how the concerns of psychologists have evolved with the larger culture.

Objectives 2

After viewing the television program and completing the assigned readings, you should be able to:

1. Explain the concept of observer bias and cite some techniques experimenters use to eliminate personal bias.

2. Define placebo effect and explain how it might be avoided.

3. Define reliability and validity and explain the difference between them.

4. Describe various psychological measurement techniques, such as self report, behavioral, and physiological measures.

5. Define correlational methods and explain why it does not establish a cause-and-effect relationship.

6. Summarize the American Psychological Association’s ethical guidelines for the treatment of humans and animals in psychological experiments, and explain why they are necessary.

7. Discuss some ways to be a wiser consumer of research.

8. Describe how a hypothesis leads to a particular experimental design.

9. Discuss how job burnout develops, how it can be studied, and how psychologists can intervene to prevent or combat it.

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If you’re wondering why we’re bringing
you a new edition of Psychology: Core
Concepts . . .
1 In the new seventh edition, we feature new cutting-edge
research on the neuroscience of social interaction, cul-
tural influences on perception, daydreaming, taste, and
meditation, as well as updates on bullying, the slower
rise of IQ scores (the Flynn effect) in developed coun-
tries, the myth of multitasking, and much more. We also
introduce readers to a groundbreaking modification of
Maslow’s famous hierarchy of needs, newly framed by
evolutionary psychologists.
2 Our lead author Philip Zimbardo has recently published
a detailed description and analysis of his famous Stanford
Prison Experiment in The Lucifer Effect: Understanding
How Good People Turn Evil. We are pleased to include
in Psychology: Core Concepts some of the insights he
presented in Lucifer—particularly the notion of the effect
of impersonal social systems, as well as social situations,
on human behavior. Ours is the only introductory text
in which you will find a discussion of how these social
systems, such as organizations and bureaucracies, create
a context that can profoundly influence the behavior of
groups and individuals.
3 Dr. Zimbardo has also done important new work on the
differences among people in their time perspective, re-
ferring to a focus on the past, the present, or the future.
This text is the only introduction to psychology to dis-
cuss the powerful influence of time perspective on our
decisions and actions.
4 In this edition, Read on MyPsychLab icons appear in
the margins indicating that additional readings are
available for students to explore. For example, one of
the Read features in Chapter 3 (Sensation and Percep-
tion) deals with the classic study of backward masking.
In Chapter 12 (Disorders and Therapy), you can read
more about an African perspective on mental disorder.
5 One of our goals in this new edition is, again, to help
you learn to “think like psychologists.” To do so, we have
placed new emphasis on two kinds of psychological think-
ing: (1) problem solving and (2) critical thinking. Every
chapter begins with a Problem and ends with a critical
analysis of an important psychological question, such as
gender differences or repressed memory.
6 We have made a special effort in the seventh edition to
provide clues throughout the chapter to help you un-
derstand the solution to the chapter-opening Problem—
which proved to be a popular feature in the last edition.
The Chapter Summary now gives a brief “answer” to
the problem as well.
7 We have designed the Critical Thinking applications at the
end of each chapter to build upon a set of critical thinking
skills introduced in Chapter One. Each of these focuses on
an issue that is popularly misunderstood (e.g., the Mozart
Effect) or contentious within the field (e.g., the evidence-
based practice debate within clinical psychology). In this
edition, we have also included the gist of the Critical
Thinking section in the Chapter Summary.
8 Reflecting advances in multicultural and cross-cultural
research, we have added even more coverage of culture
and gender throughout the text. Our goal here is two-
fold: We want you to see the relevance of psychology in
your life, and we want you to understand that psychol-
ogy is the science of behavior and mental processes that
both generalizes and differs across cultures.
Why Do You Need
This New Edition?

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Psychology
Philip G. Zimbardo
Stanford University
Robert L. Johnson
Umpqua Community College
Vivian McCann
Portland Community College
Boston Columbus Indianapolis New York San Francisco Upper Saddle River
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Seventh Edition
Core Concepts

Student Edition
ISBN-10: 0-205-18346-8
ISBN-13: 978-0-205-18346-3
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Credits and acknowledgments borrowed from other sources and reproduced, with permission, in this textbook appear on pages C-1–C-2.
Copyright © 2012, 2009, 2006 by Pearson Education, Inc.
All rights reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the
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Library of Congress Cataloging-in-Publication Data
Zimbardo, Philip G.
Psychology : core concepts / Philip G. Zimbardo, Robert L. Johnson, Vivian McCann. — 7th ed.
p. cm.
Includes bibliographical references and index.
ISBN-13: 978-0-205-18346-3
ISBN-10: 0-205-18346-8
1. Psychology. I. Johnson, Robert L. (Robert Lee) II. McCann, Vivian. III. Title.
BF121.Z53 2012
150—dc23
2011027587
1 0 9 8 7 6 5 4 3 2 1

1 Mind, Behavior, and Psychological Science 2
2 Biopsychology, Neuroscience, and Human Nature 40
3 Sensation and Perception 86
4 Learning and Human Nurture 132
5 Memory 170
6 Thinking and Intelligence 212
7 Development Over the Lifespan 264
8 States of Consciousness 322
9 Motivation and Emotion 362
10 Personality: Theories of the Whole Person 412
11 Social Psychology 458
12 Psychological Disorders 514
13 Therapies for Psychological Disorders 554
14 From Stress to Health and Well-Being 596
Glossary G-1
References R-1
Answers to Discovering Psychology Program Review Questions A-1
Photo Credits C-1
Name Index I-1
Subject Index I-7
B R I E F C O N T E N T S
v

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vii
C O N T E N T S
CHAPTER 1 Mind, Behavior, and Psychological Science 2
PROBLEM: How would psychologists test the claim that sugar
makes children hyperactive? 3
1.1 What Is Psychology—And What Is It Not? 4
Psychology: It’s More Than You Think 4
Psychology Is Not Psychiatry 6
Thinking Critically about Psychology
and Pseudo-Psychology 7
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 10
1.2 What Are Psychology’s Six Main Perspectives? 11
Separation of Mind and Body and the Modern Biological
Perspective 12
The Founding of Scientific Psychology and the Modern
Cognitive Perspective 13
The Behavioral Perspective: Focusing on Observable
Behavior 16
The Whole-Person Perspectives: Psychodynamic, Humanistic,
and Trait and Temperament Psychology 17
The Developmental Perspective: Changes Arising from Nature
and Nurture 19
The Sociocultural Perspective: The Individual in Context 19
The Changing Face of Psychology 20
PSYCHOLOGY MATTERS: Psychology as a Major 22
1.3 How Do Psychologists Develop New Knowledge? 23
Four Steps in the Scientific Method 24
Five Types of Psychological Research 27
Controlling Biases in Psychological Research 31
Ethical Issues in Psychological Research 32
PSYCHOLOGY MATTERS: The Perils of Pseudo-Psychology 33
CRITICAL THINKING APPLIED: Facilitated Communication 35
Chapter Summary 36
Discovering Psychology Viewing Guide 38
PROBLEM: What does Jill Bolte Taylor’s experience teach us
about how our brain is organized and about its amazing ability
to adapt? 42
2.1 How Are Genes and Behavior Linked? 43
Evolution and Natural Selection 43
Genetics and Inheritance 45
PSYCHOLOGY MATTERS: Choosing Your Children’s
Genes 48
2.2 How Does the Body Communicate
Internally? 49
The Neuron: Building Block of the Nervous System 50
The Nervous System 56
The Endocrine System 58
PSYCHOLOGY MATTERS: How Psychoactive Drugs Affect
the Nervous System 60
2.3 How Does the Brain Produce Behavior and Mental
Processes? 62
Windows on the Brain 63
Three Layers of the Brain 65
Lobes of the Cerebral Cortex 69
Cerebral Dominance 73
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 79
CRITICAL THINKING APPLIED: Left Brain versus Right Brain 80
Chapter Summary 81
Discovering Psychology Viewing Guide 84
CHAPTER 2 Biopsychology, Neuroscience, and Human Nature 40
CHAPTER 3 Sensation and Perception 86
PROBLEM: Is there any way to tell whether the world we “see”
in our minds is the same as the external world—and whether
we see things as most others do? 88
3.1 How Does Stimulation Become Sensation? 89
Transduction: Changing Stimulation to Sensation 90
Thresholds: The Boundaries of Sensation 91
Signal Detection Theory 93
PSYCHOLOGY MATTERS: Sensory Adaptation 93
3.2 How Are the Senses Alike? How Are They Different? 94
Vision: How the Nervous System Processes Light 94
Hearing: If a Tree Falls in the Forest . . . 100
How the Other Senses Are Like Vision and Hearing 104
Synesthesia: Sensations across the Senses 108
PSYCHOLOGY MATTERS: The Sense and Experience of Pain 109
3.3 What Is the Relationship between Sensation
and Perception? 112
Perceptual Processing: Finding Meaning in Sensation 112
Perceptual Ambiguity and Distortion 114
Theoretical Explanations for Perception 117
Seeing and Believing 124
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 125
CRITICAL THINKING APPLIED: Subliminal Perception and Subliminal
Persuasion 126
Chapter Summary 128
Discovering Psychology Viewing Guide 130 vii

viii C O N T E N T S
CHAPTER 4 Learning and Human Nurture 132
PROBLEM: Assuming Sabra’s fear of flying was a response she
had learned, could it also be treated by learning? If so, how? 134
4.1 What Sort of Learning Does Classical Conditioning
Explain? 136
The Essentials of Classical Conditioning 137
Applications of Classical Conditioning 139
PSYCHOLOGY MATTERS: Taste Aversions
and Chemotherapy 142
4.2 How Do We Learn New Behaviors By Operant
Conditioning? 142
Skinner’s Radical Behaviorism 143
The Power of Reinforcement 143
The Problem of Punishment 149
A Checklist for Modifying Operant Behavior 152
Operant and Classical Conditioning Compared 153
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 155
4.3 How Does Cognitive Psychology Explain Learning? 156
Insight Learning: Köhler in the Canaries with Chimps 157
Cognitive Maps: Tolman Finds Out What’s on a
Rat’s Mind 158
Observational Learning: Bandura’s Challenge to
Behaviorism 159
Brain Mechanisms and Learning 161
“Higher” Cognitive Learning 162
PSYCHOLOGY MATTERS: Fear of Flying Revisited 162
CRITICAL THINKING APPLIED: Do Different People Have Different
“Learning Styles”? 164
Chapter Summary 166
Discovering Psychology Viewing Guide 168
CHAPTER 5 Memory 170
PROBLEM: How can our knowledge about memory help us
evaluate claims of recovered memories? 172
5.1 What Is Memory? 172
Metaphors for Memory 173
Memory’s Three Basic Tasks 174
PSYCHOLOGY MATTERS: Would You Want a “Photographic”
Memory? 175
5.2 How Do We Form Memories? 177
The First Stage: Sensory Memory 178
The Second Stage: Working Memory 180
The Third Stage: Long-Term Memory 184
PSYCHOLOGY MATTERS: “Flashbulb” Memories: Where Were
You When . . . ? 189
5.3 How Do We Retrieve Memories? 190
Implicit and Explicit Memory 190
Retrieval Cues 191
Other Factors Affecting Retrieval 193
PSYCHOLOGY MATTERS: On the Tip of Your Tongue 194
5.4 Why Does Memory Sometimes Fail Us? 195
Transience: Fading Memories Cause Forgetting 196
Absent-Mindedness: Lapses of Attention Cause
Forgetting 198
Blocking: Access Problems 198
Misattribution: Memories in the Wrong Context 199
Suggestibility: External Cues Distort or Create Memories 200
Bias: Beliefs, Attitudes, and Opinions Distort Memories 201
Persistence: When We Can’t Forget 202
The Advantages of the “Seven Sins” of Memory 202
Improving Your Memory with Mnemonics 203
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 204
CRITICAL THINKING APPLIED: The Recovered Memory
Controversy 206
Chapter Summary 207
Discovering Psychology Viewing Guide 210

C O N T E N T S ix
CHAPTER 7 Development Over the Lifespan 264
PROBLEM: Do the amazing accounts of similarities in twins
reared apart indicate we are primarily a product of our genes?
Or do genetics and environment work together to influence
growth and development over the lifespan? 266
7.1 What Innate Abilities Does the Infant Possess? 268
Prenatal Development 268
The Neonatal Period: Abilities of the Newborn Child 269
Infancy: Building on the Neonatal Blueprint 271
PSYCHOLOGY MATTERS: Not Just Fun and Games: The Role
of Child’s Play in Life Success 277
7.2 What Are the Developmental Tasks of Childhood? 279
How Children Acquire Language 279
Cognitive Development: Piaget’s Theory 282
Social and Emotional Development 288
PSYCHOLOGY MATTERS: The Puzzle of ADHD 294
7.3 What Changes Mark the Transition of Adolescence? 296
Adolescence and Culture 296
Physical Maturation in Adolescence 297
Adolescent Sexuality 298
Neural and Cognitive Development in Adolescence 299
Moral Development: Kohlberg’s Theory 300
Social and Emotional Issues in Adolescence 302
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology: Cognitive Development in College Students 304
7.4 What Developmental Challenges Do Adults Face? 305
Early Adulthood: Explorations, Autonomy, and Intimacy 306
The Challenges of Midlife: Complexity and Generativity 308
Late Adulthood: The Age of Integrity 310
PSYCHOLOGY MATTERS: A Look Back at the Jim Twins
and Your Own Development 313
CRITICAL THINKING APPLIED: The Mozart Effect 315
Chapter Summary 316
Discovering Psychology Viewing Guide 320
CHAPTER 6 Thinking and Intelligence 212
PROBLEM: What produces “genius,” and to what extent are
the people we call “geniuses” different from others? 214
6.1 What Are the Components of Thought? 215
Concepts 215
Imagery and Cognitive Maps 217
Thought and the Brain 218
Intuition 219
PSYCHOLOGY MATTERS: Schemas and Scripts Help You
Know What to Expect 221
6.2 What Abilities Do Good Thinkers Possess? 223
Problem Solving 223
Judging and Making Decisions 227
Becoming a Creative Genius 229
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 232
6.3 How Is Intelligence Measured? 233
Binet and Simon Invent a School Abilities Test 234
American Psychologists Borrow Binet and Simon’s Idea 235
Problems with the IQ Formula 236
Calculating IQs “on the Curve” 237
IQ Testing Today 238
PSYCHOLOGY MATTERS: What Can You Do for an Exceptional
Child? 239
6.4 Is Intelligence One or Many Abilities? 242
Psychometric Theories of Intelligence 242
Cognitive Theories of Intelligence 243
The Question of Animal Intelligence 247
PSYCHOLOGY MATTERS: Test Scores and the Self-Fulfilling
Prophecy 249
6.5 How Do Psychologists Explain IQ Differences
Among Groups? 250
Intelligence and the Politics of Immigration 251
What Evidence Shows That Intelligence Is Influenced
by Heredity? 251
What Evidence Shows That Intelligence is Influenced
by Environment? 252
Heritability (Not Heredity) and Group Differences 253
PSYCHOLOGY MATTERS: Stereotype Threat 256
CRITICAL THINKING APPLIED: The Question of Gender Differences 258
Chapter Summary 259
Discovering Psychology Viewing Guide 262
CHAPTER 8 States of Consciousness 322
PROBLEM: How can psychologists objectively examine the
worlds of dreaming and other subjective mental states? 324
8.1 How Is Consciousness Related to Other Mental Processes? 324
Tools for Studying Consciousness 326
Models of the Conscious and Nonconscious Minds 327
What Does Consciousness Do for Us? 329
Coma and Related States 330
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 331
8.2 What Cycles Occur in Everyday Consciousness? 332
Daydreaming 332
Sleep: The Mysterious Third of Our Lives 333
Dreaming: The Pageants of the Night 338
PSYCHOLOGY MATTERS: Sleep Disorders 341
8.3 What Other Forms Can Consciousness Take? 344
Hypnosis 345
Meditation 347
Psychoactive Drug States 348
PSYCHOLOGY MATTERS: Dependence and Addiction 354
CRITICAL THINKING APPLIED: The Unconscious—Reconsidered 356
Chapter Summary 358
Discovering Psychology Viewing Guide 360

x C O N T E N T S
CHAPTER 10 Personality: Theories of the Whole Person 412
PROBLEM: What influences were at work to produce the
unique behavioral patterns, high achievement motivation,
and consistency over time and place that we see in the
personality of Mary Calkins? 414
10.1 What Forces Shape Our Personalities? 415
Biology, Human Nature, and Personality 416
The Effects of Nurture: Personality and the Environment 416
The Effects of Nature: Dispositions and Mental
Processes 417
Social and Cultural Contributions to Personality 417
PSYCHOLOGY MATTERS: Explaining Unusual People
and Unusual Behavior 418
10.2 What Persistent Patterns, or Dispositions, Make Up
Our Personalities? 420
Personality and Temperament 421
Personality as a Composite of Traits 422
PSYCHOLOGY MATTERS: Finding Your Type 426
10.3 Do Mental Processes Help Shape Our Personalities? 428
Psychodynamic Theories: Emphasis on Motivation
and Mental Disorder 428
Humanistic Theories: Emphasis on Human Potential
and Mental Health 439
Social-Cognitive Theories: Emphasis on Social
Learning 442
Current Trends: The Person in a Social System 445
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 445
10.4 What “Theories” Do People Use to Understand Themselves
and Others? 447
Implicit Personality Theories 447
Self-Narratives: The Stories of Our Lives 448
The Effects of Culture on Our Views of Personality 449
PSYCHOLOGY MATTERS: The Personality of Time 450
CRITICAL THINKING APPLIED: The Person–Situation
Controversy 453
Chapter Summary 454
Discovering Psychology Viewing Guide 456
CHAPTER 9 Motivation and Emotion 362
PROBLEM: Motivation is largely an internal and subjective
process: How can we determine what motivates people like
Lance Armstrong to work so hard at becoming the best in the
world at what they do? 364
9.1 What Motivates Us? 364
Why People Work: McClelland’s Theory 365
The Unexpected Effects of Rewards on Motivation 367
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 368
9.2 How Are Our Motivational Priorities Determined? 369
Instinct Theory 369
Drive Theory 370
Freud’s Psychodynamic Theory 371
Maslow’s Hierarchy of Needs 372
Putting It All Together: A New Hierarchy of Needs 373
PSYCHOLOGY MATTERS: Determining What Motivates
Others 374
9.3 Where Do Hunger and Sex Fit into the Motivational
Hierarchy? 375
Hunger: A Homeostatic Drive and a Psychological
Motive 376
The Problem of Will Power and Chocolate Cookies 379
Sexual Motivation: An Urge You Can Live Without 380
Sex, Hunger, and the Hierarchy of Needs 384
PSYCHOLOGY MATTERS: The What and Why of Sexual
Orientation 385
9.4 How Do Our Emotions Motivate Us? 387
What Emotions Are Made Of 388
What Emotions Do for Us 389
Counting the Emotions 389
Cultural Universals in Emotional Expression 390
PSYCHOLOGY MATTERS: Gender Differences in Emotion
Depend on Biology and Culture 391
9.5 What Processes Control Our Emotions? 392
The Neuroscience of Emotion 393
Arousal, Performance, and the Inverted U 396
Theories of Emotion: Resolving Some Old Issues 397
How Much Conscious Control Do We Have Over Our
Emotions? 399
PSYCHOLOGY MATTERS: Detecting Deception 403
CRITICAL THINKING APPLIED: Do Lie Detectors Really
Detect Lies? 405
Chapter Summary 407
Discovering Psychology Viewing Guide 410

C O N T E N T S xi
CHAPTER 11 Social Psychology 458
PROBLEM: What makes ordinary people willing to harm other
people, as they did in Milgram’s shocking experiment? 461
11.1 How Does the Social Situation Affect Our Behavior? 462
Social Standards of Behavior 463
Conformity 465
Obedience to Authority 471
Cross-Cultural Tests of Milgram’s Research 475
Some Real-World Extensions of the Milgram Obedience
to Authority Paradigm 477
The Bystander Problem: The Evil of Inaction 478
Need Help? Ask for It! 480
PSYCHOLOGY MATTERS: On Being “Shoe” at Yale U 482
11.2 Constructing Social Reality: What Influences Our
Judgments of Others? 483
Interpersonal Attraction 484
Loving Relationships 488
Making Cognitive Attributions 490
Prejudice and Discrimination 492
PSYCHOLOGY MATTERS: Stereotype Lift and Values
Affirmations 498
11.3 How Do Systems Create Situations That Influence
Behavior? 500
The Stanford Prison Experiment 500
Chains of System Command 502
Preventing Bullying by Systematic Changes and Reframing 504
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 507
CRITICAL THINKING APPLIED: Is Terrorism “a Senseless Act of
Violence, Perpetrated by Crazy Fanatics”? 508
Chapter Summary 510
Discovering Psychology Viewing Guide 512
PROBLEM: Is it possible to distinguish mental disorder from
merely unusual behavior? That is, are there specific signs
that clearly indicate mental disorder? 516
12.1 What Is Psychological Disorder? 517
Changing Concepts of Psychological Disorder 518
Indicators of Abnormality 521
A Caution to Readers 522
PSYCHOLOGY MATTERS: The Plea of Insanity 522
12.2 How Are Psychological Disorders Classified
in the DSM-IV ? 524
Overview of the DSM-IV Classification System 524
Mood Disorders 526
Anxiety Disorders 530
Somatoform Disorders 534
Dissociative Disorders 535
Schizophrenia 537
Developmental Disorders 541
Personality Disorders 542
Adjustment Disorders and Other Conditions: The Biggest
Category of All 544
Gender Differences in Mental Disorders 544
PSYCHOLOGY MATTERS: Shyness 544
12.3 What Are the Consequences of Labeling People? 545
Diagnostic Labels, Labeling, and Depersonalization 546
The Cultural Context of Psychological Disorder 546
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 547
CRITICAL THINKING APPLIED: Insane Places Revisited—Another
Look at the Rosenhan Study 548
Chapter Summary 550
Discovering Psychology Viewing Guide 552
CHAPTER 12 Psychological Disorders 514

xii C O N T E N T S
Glossary G-1
References R-1
Answers to Discovering Psychology Program Review Questions A-1
Photo Credits C-1
Name Index I-1
Subject Index I-7
CHAPTER 14 From Stress to Health and Well-Being 596
PROBLEM: Were the reactions and experiences of the 9/11
firefighters and others at the World Trade Center attacks
typical of people in other stressful situations? And what
factors explain individual differences in our physical and
psychological responses to stress? 598
14.1 What Causes Distress? 600
Traumatic Stressors 601
Chronic Stressors 606
PSYCHOLOGY MATTERS: Student Stress 611
14.2 How Does Stress Affect Us Physically? 613
Physiological Responses to Stress 614
Stress and the Immune System 617
PSYCHOLOGY MATTERS: Cognitive Appraisal of Ambiguous
Threats 619
14.3 Who Is Most Vulnerable to Stress? 620
Type A Personality and Hostility 622
Locus of Control 623
Hardiness 624
Optimism 625
Resilience 626
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 628
14.4 How Can We Transform Negative Stress Into Positive
Life Strategies? 629
Psychological Coping Strategies 630
Positive Lifestyle Choices: A “Two-for-One” Benefit to Your
Health 634
Putting It All Together: Developing Happiness and Subjective
Well-Being 637
PSYCHOLOGY MATTERS: Behavioral Medicine and Health
Psychology 639
CRITICAL THINKING APPLIED: Is Change Really Hazardous
to Your Health? 641
Chapter Summary 643
Discovering Psychology Viewing Guide 646
CHAPTER 13 Therapies for Psychological Disorders 554
PROBLEM: What is the best treatment for Derek’s depression:
psychological therapy, drug therapy, or both? More broadly,
the problem is this: How do we decide among the available
therapies for any of the mental disorders? 556
13.1 What Is Therapy? 556
Entering Therapy 557
The Therapeutic Alliance and the Goals of Therapy 557
Therapy in Historical and Cultural Context 559
PSYCHOLOGY MATTERS: Paraprofessionals Do Therapy,
Too 560
13.2 How Do Psychologists Treat Psychological Disorders? 561
Insight Therapies 562
Behavior Therapies 568
Cognitive–Behavioral Therapy: A Synthesis 571
Evaluating the Psychological Therapies 574
PSYCHOLOGY MATTERS: Where Do Most People Get
Help? 576
13.3 How Is the Biomedical Approach Used to Treat
Psychological Disorders? 577
Drug Therapy 577
Other Medical Therapies for Psychological Disorders 581
Hospitalization and the Alternatives 583
PSYCHOLOGY MATTERS: What Sort of Therapy Would You
Recommend? 584
13.4 How Do the Psychological Therapies and Biomedical
Therapies Compare? 585
Depression and Anxiety Disorders: Psychological versus
Medical Treatment 587
Schizophrenia: Psychological versus Medical
Treatment 587
“The Worried Well” and Other Problems: Not Everyone Needs
Drugs 588
PSYCHOLOGY MATTERS: Using Psychology to Learn
Psychology 588
CRITICAL THINKING APPLIED: Evidence-Based Practice 589
Chapter Summary 592
Discovering Psychology Viewing Guide 594

P R E FA C E xiii
T O T H E S T U D E N T . . .
There is one simple formula for academic success, and the following demonstration will show you what it is. Study this array of letters for a few seconds:
I B M U F O F B I C I A
Now, without peeking, write down as many of the letters as you can (in the correct
order).
Most people remember about five to seven letters correctly. A few people get them
all. How do these exceptional few do it? They find a pattern. (You may have noticed
some familiar initials in the array above: IBM, UFO, FBI, CIA.) Finding the pattern
greatly eases the task because you can draw on material that is already stored in mem-
ory. In this case, all that needs to be remembered are four “chunks” of information
instead of 12 unrelated letters.
The same principle applies to material you study for your psychology class. If you
try to remember each piece of information as a separate item, you will have a difficult
time. But if instead you look for patterns, you will find your task greatly simplified—
and much more enjoyable.
USING PSYCHOLOGY TO LEARN PSYCHOLOGY
So, how can you identify the patterns? Your friendly authors have developed several
learning features that will make meaningful patterns in the text stand out clearly:
Core Concepts We have organized each major section of every chapter around a single
big idea called a Core Concept. For example, one of the four Core Concepts in Chapter 5,
Memory, says:
Core Concept 5.4
Human memory is an information-processing system that works
constructively to encode, store, and retrieve information.
The Core Concept, then, becomes the central theme around which about 10 pages of
material—including several new terms—are organized. As you read each chapter, keep-
ing the Core Concept in mind will help you encode the new terms and ideas related to
that concept, store them in your memory, and later retrieve them when you are being
tested. To borrow an old saying, the Core Concepts become the “forest,” while the
details of the chapter become the “trees.”
Key Questions Each Core Concept is introduced by a Key Question that also serves as
a main heading in the chapter. Here, for example, is a Key Question from the Memory
chapter:
5.4 KEY QUESTION
Why Does Memory Sometimes Fail Us?
Key Questions such as this will help you anticipate the most important point, or the
Core Concept, in the section. In fact, the Core Concept always provides a brief answer
to the Key Question. Think of the Key Question as the high beams on your car, helping
xiii

xiv T O T H E S T U D E N T
you focus on what lies ahead. Our Key Questions should also serve as guides for you
in posing questions of your own about what you are reading.
Both the Key Questions and the Core Concepts later reappear as organizing fea-
tures of the Chapter Summary.
Psychology Matters Psychology has many captivating connections with events in the
news and in everyday life, and we have explored one of these connections at the end
of each major section in every chapter. To illustrate, here are some examples from the
Memory chapter:
• Would You Want a “Photographic” Memory?
• “Flashbulb” Memories: Where Were You When . . . ?
• On the Tip of Your Tongue
Such connections—practical, down to earth, and fascinating—will help you link your
study of psychology with your real-life experiences. They will also help you critically
evaluate many of the psychological ideas you encounter in the media—as when you see
news stories that begin with “psychological research shows that . . .” By the end of this
course, you will become a much wiser consumer of such information.
Psychology Matters: Using Psychology to Learn Psychology A special Psychology
Matters section in every chapter explains how you can apply new knowledge from
the chapter to make your studying more effective. For example, in Chapter 2,
Biopsychology, Neuroscience, and Human Nature, we tell you how to put your
understanding of the brain to work for more efficient learning. Similarly, at the end
of Chapter 9, Motivation and Emotion, we explain how to use the psychological
concept of “flow” to boost your academic motivation. Thus, Using Psychology to
Learn Psychology not only reinforces points that you have studied but also brings the
material home with immediate and practical applications to your life in college.
Do It Yourself! Throughout the book we have scattered active-learning demonstrations
like the one in which you were asked to memorize the letters I B M U F O F B I C I A.
Besides being fun, these activities have the serious purpose of illustrating important
principles discussed in the text. In Chapter 5, for example, one Do It Yourself! box
helps you find the capacity of your short-term memory; another lets you test your
“photographic memory” ability.
Check Your Understanding Whether you’re learning psychology, soccer, or the
saxophone, you need feedback on your progress, and that’s exactly what you will get
from the Check Your Understanding quizzes. These quizzes appear at the end of every
major section in the chapter, offering you a quick checkup indicating whether you have
assimilated the main points from what you have read. Some questions call for simple
recall; others call for deeper analysis or application of material. Some are multiple-
choice questions; some are short-answer essay questions. These exercises will help you
determine how well you have mastered the material.
MyPsychLab Integration Throughout the text, you will find marginal icons that link to
important videos, simulations, podcasts, and activities you can find on MyPsychLab.
New to this edition, we have developed reading activities (called Read on MyPsychLab)
that will allow you to explore interesting topics more deeply. There are many more
resources on MyPsychLab than those highlighted in the text, but the icons draw
attention to some of the most high-interest materials. If you did not receive an access
code with your text, you can purchase access at www.mypsychlab.com.
Connection Arrows Links to important topics discussed in other chapters are often
cross-referenced with an arrow in the margin, as you can see in the sample here.
These links will help you integrate your new knowledge with information you have
already learned, or will show you where in a later chapter you can find out more
Study and Review at MyPsychLab
Read the Document at MyPsychLab
Simulate the Experiment at MyPsychLab
Explore the Concept at MyPsychLab
Watch the Video at MyPsychLab
Listen to the Podcast at MyPsychLab

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T O T H E S T U D E N T xv
about what you are reading. Connecting these concepts in your mind will help you
remember them.
Marginal Glossary The most important terms appear in boldface, with their glossary
definitions readily accessible in the margin. We list these key terms again in the Chapter
Summary. Then, at the end of the book, a comprehensive Glossary gathers together all
the key terms and definitions from each chapter in one easy-to-find location.
Chapter Summaries We have written our Chapter Summaries to provide you with an
overview of main points in each chapter—to help you preview and review the chapter.
The summaries are organized around the Key Questions and Core Concepts introduced
within the chapter to facilitate review and mastery of chapter material. But we offer
one caution: Reading the Chapter Summary will not substitute for reading the entire
chapter! Here’s a helpful hint: We recommend that you read the summary before you
read the rest of the chapter to get a flavor of what’s ahead, then reread the summary
after you finish the chapter. Reading the summary before will provide a framework for
the material so that it can be more easily encoded and stored in your memory. And,
naturally, reviewing the summary after reading the chapter will reinforce what you
have just learned so that you can retrieve it when needed on an examination.
THINKING LIKE A PSYCHOLOGIST
Learning all the facts and definitions of psychology won’t make you a psychologist.
Beyond the facts, thinking like a psychologist requires learning some problem-solving
skills and critical thinking techniques that any good psychologist should possess. With
this goal in mind, we have added two unique features to this book.
Chapter-Opening Problems Each chapter begins with an important problem that you will
learn how to solve with the tools you acquire in your reading. Examples of the chapter-
opening problems include testing the claim that sweet treats give children a “sugar high,”
evaluating claims of recovered memories, and judging the extent to which the people we
call “geniuses” are different from the rest of us.
Critical Thinking Applied At the end of each chapter, you will be asked to consider
issues disputed among psychologists and issues raised in the media, such as the nature
of the unconscious mind and the effects of subliminal persuasion. Each of these issues
requires a skeptical attitude and the application of a special set of critical thinking skills
that we will introduce in Chapter 1.
DISCOVERING PSYCHOLOGY VIDEOS
At the end of each chapter, you will notice viewing guides for Discovering Psychology,
a 26-part video series produced by WGBH and Annenberg Media and narrated by the
lead author of this textbook, Phil Zimbardo. The videos provide an overview of his-
toric and current theories of human behavior and feature many of the researchers and
studies introduced in this textbook. You can access the Discovering Psychology videos
and additional viewing resources through MyPsychLab (www.mypsychlab.com), the
online companion to this textbook.
We have one final suggestion to help you succeed in psychology: This book is filled
with examples to illustrate the most important ideas, but you will remember these
ideas longer if you generate your own examples as you study. This habit will make the
information yours as well as ours. And so we wish you a memorable journey through
the field we love.
Phil Zimbardo
Bob Johnson
Vivian McCann

www.mypsychlab.com

T O T H E I N S T R U C T O R . . .
Psychology has undergone remarkable changes since 2008, when we finished writing the previous edition of Psychology: Core Concepts. Here are just a few
examples of the new developments we have included in this seventh edition:
• The brain’s “default network,” involving parts of the temporal lobe, the prefrontal
cortex, and the cingulate cortex, becomes active when people focus their attention
internally—when they are remembering personal events, making plans, or imagin-
ing the perspectives of others. Unfortunately, daydreamers activating this default
network while studying will probably not remember the material they have just
studied.
• New research shows that analgesics such as Tylenol, normally used to treat
physical pain, can reduce the painful psychological sensations resulting from
social rejection and ruminating about unhappy relationships.
• Also in the realm of sensation, taste researcher Linda Bartoshuk has discovered a
“Rosetta Stone,” enabling her to compare objectively the intensities of taste
sensations experienced by different individuals.
• Meanwhile, perceptual psychologists have recently used brain scans to confirm the
assertion that Americans and Asians perceive scenes differently.
• Brain scans have also enabled researchers to assess patients who have been classi-
fied as in persistent vegetative states—and predict which ones might improve.
• In healthy individuals, scans have detected changes in the brains of volunteers who
have undergone intensive training in meditation. The changes are most obvious in
brain areas associated with memory, emotional processing, attention, and stress
reduction.
• As cognitive psychologists continue to puzzle over the Flynn effect, IQ scores con-
tinue to rise—but new studies show that the rise is slowing in developed countries
of the West.
• Cognitive research also shows that one in four auto accidents results from the
driver failing to notice hazardous conditions while using a cell phone—a bad
decision probably deriving from a mistaken belief in multitasking. (Perhaps
future research will determine whether the IQs of these drivers fall above or
below the rising average.)
• New research by our own Phil Zimbardo shows that decisions can also be
influenced by a personality trait that he calls time perspective—referring to
a past, present, or future orientation.
• However, the ultimate influence on our decisions lies in natural selection, accord-
ing to evolutionary psychologists—who have recently proposed a major new and
controversial modification of Maslow’s famous hierarchy of needs.
In all, we have included some 350 new references in this new edition—gleaned from
literally thousands we have perused. Which is to say that psychological knowledge
continues to grow, with no end in sight. As a result, many introductory textbooks have
grown to daunting proportions. Meanwhile, our introductory courses remain the same
length—with the material ever more densely packed. We cannot possibly introduce
students to all the concepts in psychology, nor can our students possibly remember
everything.
The problem is not just one of volume and information overload; it is also a prob-
lem of meaningfulness. So, while we have aimed to cover less detail than do the more
encyclopedic texts, we have not given you a watered-down “brief edition” book. The
result is an emphasis on the most important and meaningful ideas in psychology.
xvi

T O T H E I N S T R U C T O R xvii
Our inspiration for Psychology: Core Concepts came from psychological research:
specifically, a classic study of chess players by Dutch psychologist and chess master
Adriaan de Groot (1965). His work, as you may recall, involved remembering the
locations of pieces on a chessboard. Significantly, when the pieces were placed on
the board at random, chess experts did no better than novices. Only when the pat-
terns made sense—because they represented actual game situations—did the experts
show an advantage. Clearly, meaningful patterns are easier to remember than random
assignments.
In applying de Groot’s findings to Psychology: Core Concepts, our goal has been
to present a scientific overview of the field of psychology within meaningful patterns
that will help students better remember what they learn so that they can apply it in
their own lives. Thus, we have organized each major section of every chapter around
a single, clear idea that we call a Core Concept, which helps students focus on the big
picture so they don’t become lost in the details.
From the beginning, our intention in writing Psychology: Core Concepts has been
to offer students and instructors a textbook that combines a sophisticated introduc-
tion to the field of psychology with pedagogy that applies the principles of psychology
to the learning of psychology, all in a manageable number of pages. Even with all the
new material we have included, the book remains essentially the same size—which, of
course, meant making some tough decisions about what to include, what to delete, and
what to move into our extensive collection of ancillary resources.
Our goal was to blend great science with great teaching and to provide an alter-
native to the overwhelmingly encyclopedic tomes or skimpy “brief edition” texts that
have been traditionally offered. We think you will like the introduction to psychol-
ogy presented in this book—both the content and the pedagogical features. After all,
it’s a text that relies consistently on well-grounded principles of psychology to teach
psychology.
NEW TO THIS EDITION
This edition of Psychology: Core Concepts is certainly no perfunctory revision or slap-
dash update. And here’s why . . .
We have reconceptualized our goal of helping students learn to “think like
psychologists.” These days, of course, everyone emphasizes critical thinking. The new
edition of Psychology: Core Concepts, however, gives equal weight to that other essen-
tial thinking skill: problem solving.
To encourage the sort of problem solving psychologists do, every chapter begins
with a Problem, a feature we introduced in the last edition. The Problem grows out of
the opening vignette and requires, for its solution, material developed in the chapter. In
this edition, we have focused on helping readers discover, throughout each chapter, the
“clues” that lead to the solution of the problem.
But we have not neglected critical thinking. Throughout the text, we deal with
common psychological misconceptions—such as the notion that venting anger gets it
“out of your system” or the belief that punishment is the most effective way of chang-
ing behavior. And in our Critical Thinking Applied segment at the end of each chapter,
we also focus on an important psychological issue in the popular media or an ongoing
debate within the field:
• Can “facilitated communication” help us understand people with autism?
• Left vs. right brain: Do most of us use only one side of the brain?
• Can our choices be influenced by subliminal messages?
• Do people have different “learning styles”?
• The recovered memory controversy: How reliable are reports of long-forgotten
memories of sexual abuse?
• Gender issues: Are we more alike or more different?
• The “Mozart Effect”: Can music make babies smarter?

xviii T O T H E I N S T R U C T O R
• The Unconscious reconsidered: Has modern neuroscience reshaped Freud’s
concept of the unconscious mind?
• Do lie detectors really detect lies?
• The person-situation controversy: Which is the more important influence on our
behavior?
• Is terrorism “a senseless act of violence, perpetrated by crazy fanatics”?
• Insane places revisited: Did Rosenhan get it right?
• Evidence-based practice: Should clinicians be limited by the tested-and-true?
• Is change really hazardous to your health?
But that’s not all. We have made extensive updates to the text (in addition to the new
research listed above). And we have improved the pedagogical features for which
Psychology: Core Concepts is known and loved. To give a few examples, we have:
• added MyPsychLab icons throughout the margins to highlight important videos,
simulations, podcasts, and additional resources for students to explore online. New
to this edition, we have created Read on MyPsychLab activities that allow students to
read and answer questions about many interesting topics more deeply online.
• shifted the focus of psychology’s six main perspectives to practical applications,
giving a concrete example of a real-life problem for each.
• clarified and updated our discussion of the scientific method to reflect more
accurately how research is done in a real-world context.
• added material on interpreting correlations—to help students use the notions of
correlation and causation more accurately in their everyday lives.
• simplified and consolidated our discussion of the split-brain experiments.
• updated material on flashbulb memories, using up-to-date examples.
• created a new section on cognitive theories of intelligence.
• added a new Psychology Matters piece entitled “Not Just Fun and Games: The
Role of Child’s Play in Life Success,” telling of the growing role of self-control in
life success, and how parents and teachers can help nurture this important ability.
• added new material on Vygotsky’s theory, including scaffolding and the zone of
proximal development, plus new material on neural development in adolescence.
• revised and expanded the sections on daydreaming and on both REM and NREM
sleep to reflect important new research.
• changed the order of topics in the Motivation and Emotion chapter, bringing
in new material on practical ways of motivating people, updating the section on
sexual orientation, and presenting a revised hierarchy of needs based in evolutionary
psychology.
• added new material on cross-cultural differences in shyness, Carol Dweck’s
research on mindset, and individual differences in time perspective.
• updated the section on positive psychology.
• updated the Heroic Defiance section, including new examples from the recent
Egyptian protests and new material on events at the Abu Ghraib prison.
• added new examples of recent replications of Milgram’s obedience experiment.
• added new material on bullying, the jigsaw classroom, and stereotype lift.
• reconceptualized depression in terms of Mayberg’s model, which emphasizes three
factors: biological vulnerability, external stressors, and abnormality of the mood-
regulation circuits in the brain. Also presented the new studies on the value of
exercise in combating depression and the anxiety disorders.
• added new material on psychopathy—which is attracting increasing interest but is
not a DSM-IV disorder.
• discussed the growing rift within clinical psychology (and between APA and APS)
over empirically supported treatments and empirically based practice.

T O T H E I N S T R U C T O R xix
• updated the information on telehealth therapy strategies.
• connected the discussion of traumatic stress to the 2011 earthquake in Japan.
• added a new Do It Yourself! The Undergraduate Stress Questionnaire: How Stressed
Are You?
We think you will find the seventh edition up-to-date and even more engaging for
students than the previous edition. But the changes are not limited to the book itself.
Please allow us to toot our horns for the supplements available to adopters.
TEACHING AND LEARNING PACKAGE
The following supplements will also enhance teaching and learning for you and your
students:
Instructor’s Manual Written and compiled by Sylvia Robb of Hudson County Community
College, includes suggestions for preparing for the course, sample syllabi, and current
trends and strategies for successful teaching. Each chapter offers integrated teaching
outlines, lists the Key Questions, Core Concepts, and Key Terms for each chapter for quick
reference, an extensive bank of lecture launchers, handouts, and activities, crossword
puzzles, and suggestions for integrating third-party videos, music, and Web resources.
The electronic format features click-and-view hotlinks that allow instructors to quickly
review or print any resource from a particular chapter. This resource saves prep work and
helps you maximize your classroom time.
Test Bank Written by Jason Spiegelman of Community College of Baltimore County,
has provided an extensively updated test bank containing more than 2,000 accuracy-
checked questions, including multiple choice, completion (fill-in-the-blank and short
answer), and critical essays. Test item questions have been also written to test student
comprehension of select multimedia assets found with MyPsychLab for instructors
who wish to make MyPsychLab a more central component of their course. In addition
to the unique questions listed previously, the Test Bank also includes all of the Check
Your Understanding questions from the textbook and all of the test questions from the
Discovering Psychology Telecourse Faculty Guide for instructors who wish to reinforce
student use of the textbook and video materials. All questions include the correct answer,
page reference, difficulty ranking, question type designation, and correlations to American
Psychological Association (APA) Learning Goal/Outcome. A new feature of the Test Bank
is the inclusion of rationales for each correct answer and the key distracter in the multiple-
choice questions. The rationales help instructors reviewing the content to further evaluate
the questions they are choosing for their tests and give instructors the option to use the
rationales as an answer key for their students. Feedback from current customers indicates
this unique feature is very useful for ensuring quality and quick response to student
queries. A two-page Total Assessment Guide chapter overview makes creating tests easier
by listing all of the test items in an easy-to-reference grid. The Total Assessment Guide
organizes all test items by text section and question type/level of difficulty. All multiple-
choice questions are categorized as factual, conceptual, or applied.
The Test Bank comes with Pearson MyTest, a powerful assessment-generation
program that helps instructors easily create and print quizzes and exams. Ques-
tions and tests can be authored online, allowing instructors ultimate flexibility and
the ability to efficiently manage assessments anytime, anywhere! Instructors can easily
access existing questions and then edit, create, and store them using simple drag-and-
drop and Word-like controls. Data on each question provide information relevant to dif-
ficulty level and page number. In addition, each question maps to the text’s major section
and learning objective. For more information, go to www.PearsonMyTest.com.
NEW Interactive PowerPoint Slides These slides, available on the Instructor’s Resource
DVD (ISBN 0-205-58439-7), bring the Psychology: Core Concepts design right into
the classroom, drawing students into the lecture and providing wonderful interactive

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xx T O T H E I N S T R U C T O R
activities, visuals, and videos. A video walk-through is available and provides clear
guidelines on using and customizing the slides. The slides are built around the text’s
learning objectives and offer many links across content areas. Icons integrated throughout
the slides indicate interactive exercises, simulations, and activities that can be accessed
directly from the slides if instructors want to use these resources in the classroom.
A Set of Standard Lecture PowerPoint Slides Written by Beth M. Schwartz, Randolph
College, is also offered and includes detailed outlines of key points for each chapter
supported by selected visuals from the textbook. A separate Art and Figure version
of these presentations contains all art from the textbook for which Pearson has been
granted electronic permissions.
Classroom Response System (CRS) Power Point Slides Classroom Response System
questions (“Clicker” questions) are intended to form the basis for class discussions as
well as lectures. The incorporation of the CRS questions into each chapter’s slideshow
facilitates the use of “clickers”—small hardware devices similar to remote controls,
which process student responses to questions and interpret and display results in real
time. CRS questions are a great way to get students involved in what they are learning,
especially because many of these questions address specific scientific thinking skills
highlighted in the text. These questions are available on the Instructor’s Resource DVD
(ISBN 0-205-85439-7) and also online at http://pearsonhighered.com/irc.
Instructor’s Resource DVD (ISBN 0-205-85439-7) Bringing all of the Seventh Edition’s
instructor resources together in one place, the Instructor’s DVD offers both versions of
the PowerPoint presentations, the Classroom Response System (CRS), the electronic
files for the Instructor’s Manual materials, and the Test Item File to help instructors
customize their lecture notes.
The NEW MyPsychLab The NEW MyPsychLab combines original online materials
with powerful online assessment to engage students, assess their learning, and help
them succeed. MyPsychLab ensures students are always learning and always improving.
• New video: New, exclusive 30-minute video segments for every chapter take the
viewer from the research laboratory to inside the brain to out on the street for
real-world applications.
• New experiments: A new experiment tool allows students to experience psychol-
ogy. Students do experiments online to reinforce what they are learning in class
and reading about in the book.
• New BioFlix animations: Bring difficult-to-teach biological concepts to life with
dramatic “zoom” sequences and 3D movement.
• eText: The Pearson eText lets students access their textbook anytime, anywhere, in
any way they want it, including listening to it online.
• New concept mapping: A new concept-mapping tool allows students to create
their own graphic study aids or notetaking tools using preloaded content from
each chapter. Concept maps can be saved, e-mailed, or printed.
• Assessment: With powerful online assessment tied to every video, application, and
chapter of the text, students can get immediate feedback. Instructors can see what
their students know and what they don’t know with just a few clicks. Instruc-
tors can then personalize MyPsychLab course materials to meet the needs of their
students.
• New APA assessments: A unique bank of assessment items allows instructors to
assess student progress against the American Psychological Association’s Learning
Goals and Outcomes. These assessments have been keyed to the APA’s latest pro-
gressive Learning Outcomes (basic, developing, advanced) published in 2008.
Proven Results Instructors and students have been using MyPsychLab for nearly ten
years. To date, more than 500,000 students have used MyPsychLab. During that time,

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T O T H E I N S T R U C T O R xxi
three white papers on the efficacy of MyPsychLab were published. Both the white
papers and user feedback show compelling results: MyPsychLab helps students succeed
and improve their test scores. One of the key ways MyPsychLab improves student
outcomes is by providing continuous assessment as part of the learning process. Over
the years, both instructor and student feedback have guided numerous improvements,
making MyPsychLab even more flexible and effective.
Please contact your local Pearson representative for more information on MyPsychLab.
For technical support for any of your Pearson products, you and your students can contact
http://247.pearsoned.com.
NEW MyPsychLab Video Series (17 episodes) This new video series offers instructors
and students the most current and cutting-edge introductory psychology video content
available anywhere. These exclusive videos take the viewer into today’s research
laboratories, inside the body and brain via breathtaking animations, and onto the street
for real-world applications. Guided by the Design, Development and Review team, a
diverse group of introductory psychology instructors, this comprehensive series features
17 half-hour episodes organized around the major topics covered in the introductory
psychology course syllabus. For maximum flexibility, each half-hour episode features
several brief clips that bring psychology to life:
• The Big Picture introduces the topic of the episode and provides the hook to draw
students fully into the topic.
• The Basics uses the power of video to present foundational topics, especially those
that students find difficult to understand.
• Special Topics delves deeper into high-interest and cutting-edge topics, showing
research in action.
• In the Real World focuses on applications of psychological research.
• What’s in It for Me? These clips show students the relevance of psychological
research to their own lives.
Available in MyPsychLab and also on DVD to adopters of Pearson psychology text-
books (ISBN 0-205-03581-7).
Discovering Psychology Telecourse Videos Written, designed, and hosted by Phil Zimbardo
and produced by WGBH Boston in partnership with Annenberg Media, this series is a
perfect complement to Psychology: Core Concepts. Discovering Psychology is a landmark
educational resource that reveals psychology’s contribution not only to understanding the
puzzles of behavior but also to identifying solutions and treatments to ease the problems of
mental disorders. The video series has won numerous prizes and is widely used in the United
States and internationally. The complete set of 26 half-hour videos is available for purchase
(DVD or VHS format) from Annenberg Media. The videos are also available online in a
streaming format that is free (www.learner.org), and, for the convenience of instructors and
students using Psychology: Core Concepts, links to these online videos have been included
in the MyPsychLab program that accompanies the textbook. A student Viewing Guide
is found at the end of every chapter within Psychology: Core Concepts, with additional
Viewing Guide resources also available online within MyPsychLab.
Discovering Psychology Telecourse Faculty Guide (ISBN 0-205-69929-4) The Telecourse
Faculty Guide provides guidelines for using Discovering Psychology as a resource within
your course. Keyed directly to Psychology: Core Concepts, the faculty guide includes the
complete Telecourse Study Guide plus suggested activities; suggested essays; cited studies;
instructional resources, including books, articles, films, and websites; video program
test questions with answer key; and a key term glossary. Test questions for Discovering
Psychology also reappear in the textbook’s test bank and MyTest computerized test bank.
Student Study Guide (ISBN 0-205-25299-0) This robust study guide, written by
Jane P. Sheldon of University of Michigan-Dearborn, is filled with guided activities and
in-depth exercises to promote student learning. Each chapter includes worksheets that

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xxii T O T H E I N S T R U C T O R
give students a head start on in-class note taking; a full list of key terms with page
references; a collection of demonstrations, activities, exercises, and three short practice
quizzes; and one comprehensive chapter exam with critical-thinking essay questions
and concept maps to help you study for your quizzes and exams. The appendix includes
answers to all of the practice activities, tests, and concept maps.
ACCESSING ALL RESOURCES
For a list of all student resources available with Psychology: Core Concepts, Seventh
Edition, go to www.mypearsonstore.com, enter the text ISBN (0-205-18346-8), and
check out the “Everything That Goes with It” section under the book cover.
For access to all instructor supplements for Psychology: Core Concepts, Seventh
Edition go to http://pearsonhighered.com/irc and follow the directions to register
(or log in if you already have a Pearson user name and password). Once you have
registered and your status as an instructor is verified, you will be e-mailed a log-in name
and password. Use your log-in name and password to access the catalog. Click on the
“online catalog” link, click on “psychology” followed by “introductory psychology,”
and then the Zimbardo/Johnson/McCann, Psychology: Core Concepts, Seventh Edition
text. Under the description of each supplement is a link that allows you to download
and save the supplement to your desktop.
You can request hard copies of the supplements through your Pearson sales representa-
tive. If you do not know your sales representative, go to http://www.pearsonhighered.com/
replocator/ and follow the directions. For technical support for any of your Pearson prod-
ucts, you and your students can contact http://247.pearsoned.com.
A NOTE OF THANKS
Nobody ever realizes the magnitude of the task when taking on a textbook-writing
project. Acquisitions Editor Amber Chow and Executive Editor Stephen Frail deftly
guided (and prodded) us through this process. The vision of the seventh edition con-
fronted reality under the guidance of Deb Hanlon, our tenacious Senior Development
Editor, who made us work harder than we had believed possible. Assistant Editor Kerri
Hart-Morris managed our spectacular ancillaries package.
The job of making the manuscript into a book fell to Shelly Kupperman, our
Production Project Manager at Pearson Education; Andrea Stefanowicz, our Senior
Project Manager at PreMediaGlobal; and Kim Husband, our copyeditor. We think they
did an outstanding job—as did our tireless photo researcher, Ben Ferrini.
We are sure that none of the above would be offended if we reserve our deepest
thanks for our spouses, closest colleagues, and friends who inspired us, gave us the
caring support we needed, and served as sounding boards for our ideas. Phil thanks
his wonderful wife, Christina Maslach, for her endless inspiration and for modeling
what is best in academic psychology. He has recently passed a milestone of 50 years
of teaching the introductory psychology course, from seminar size to huge lectures to
more than 1,000 students. Phil continues to give lectures and colloquia to college and
high school groups throughout the country and overseas. He still gets a rush from lec-
turing and from turning students on to the joys and fascination of psychology. His new
“psych rock star” status comes mostly from generations of students who have grown
up watching him perform on the Discovering Psychology video series in their high
school and college psychology courses.
Bob is grateful to his spouse, best friend, and best editor Michelle, who has for years
put up with his rants on topics psychological, his undone household chores, and much
gratification delayed—mostly without complaint. She has been a wellspring of understand-
ing and loving support and the most helpful of reviewers. His thanks, too, go to Rebecca,
their daughter, who has taught him the practical side of developmental psychology—and
now, much to her own astonishment and an undergraduate lapse into sociology, pos-
sesses her own graduate degree in psychology. In addition, he is indebted to many friends,

www.mypearsonstore.com

http://247.pearsoned.com

http://www.pearsonhighered.com/replocator/

http://pearsonhighered.com/irc

T O T H E I N S T R U C T O R xxiii
most of whom are not psychologists but who are nevertheless always eager to raise and
debate interesting issues about the applications of psychology to everyday life. Readers
will find topics they have raised throughout the book and especially in the chapter-opening
“problems” and in the critical thinking sections at the end of each chapter.
Vivian’s thanks go first to her husband, Shawn, and their sons, Storm and Blaze.
All three of these amazing men are endless sources of love, support, inspiration, fun,
and delight. They also generously allow Vivian to use them as examples of a multi-
tude of concepts in her classes! Vivian also appreciates the many students, friends, and
colleagues who have both encouraged and challenged her over the years.
We would especially like to thank Michelle Billies, Nikita Duncan, George Slavich,
and Christina Zimbardo for their exceptional help as we revised and prepared this
edition for print.
Many psychological experts and expert teachers of introductory psychology also
shared their constructive criticism with us on every chapter and feature of the seventh
edition of this text:
Thomas Beckner, Trine University
Chris Brill, Old Dominion University
Allison Buskirk-Cohen, Delaware Valley
College
Christie Chung, Mills College
Elizabeth Curtis, Long Beach City College
Linda DeKruif, Fresno City College
Meliksah Demir, Northern Arizona
University
Roger Drake, Western State College of
Colorado
Denise Dunovant, Hudson County
Community College
Arthur Frankel, Salve Regina University
Marjorie Getz, Bradley University
Nancy Gup, Georgia Perimeter College
Carrie Hall, Miami University
Jeremy Heider, Stephen F. Austin State
University
Allen Huffcutt, Bradley University
Kristopher Kimbler, Florida Gulf Coast
University
Sue Leung, Portland Community College
Brian Littleton, Kalamazoo Valley
Community College
Annette Littrell, Tennessee Tech University
Mark Loftis, Tennessee Tech University
Lillian McMaster, Hudson County
Community College
Karen Marsh, University of
Minnesota–Duluth
Jim Matiya, Florida Gulf Coast University
Nancy Melucci, Long Beach City College
Jared Montoya, The University of Texas
at Brownsville
Suzanne Morrow, Old Dominion
University
Katy Neidhart, Cuesta College
Donna Nelson, Winthrop University
Barbara Nova, Dominican University of
California
Elaine Olaoye, Brookdale Community
College
Karl Oyster, Tidewater Community
College
Sylvia Robb, Hudson County
Community College
Nancy Romero, Lone Star College
Beverly Salzman, Housatonic
Community College
Hildur Schilling, Fitchburg State College
Bruce Sherwin, Housatonic Community
College
Hilary Stebbins, Virginia Wesleyan
College
Doris Van Auken, Holy Cross College
Matthew Zagummy, Tennessee Tech
University
We also thank the reviewers of the previous editions of Psychology: Core Concepts
and hope that they will recognize their valued input in all that is good in this text:
Gordon Allen, Miami University
Beth Barton, Coastal Carolina
Community College
Linda Bastone, Purchase College, SUNY
Susan Beck, Wallace State College
Michael Bloch, University of San Francisco
Michele Breault, Truman State University
John H. Brennecke, Mount San Antonio
College
T. L. Brink, Crafton Hills College

xxiv T O T H E I N S T R U C T O R
Jay Brown, Southwest Missouri State
University
Sally S. Carr, Lakeland Community
College
Saundra Ciccarelli, Gulf Coast
Community College
Wanda Clark, South Plains College
Susan Cloninger, The Sage Colleges
John Conklin, Camosun College (Canada)
Michelle L. Pilati Corselli (Rio Hondo
College)
Sara DeHart-Young, Mississippi State
University
Janet DiPietro, John Hopkins University
Diane Finley, Prince George’s
Community College
Krista Forrest, University of Nebraska at
Kearney
Lenore Frigo, Shasta College
Rick Froman, John Brown University
Arthur Gonchar, University of LaVerne
Peter Gram, Pensacola Junior College
Jonathan Grimes, Community College of
Baltimore County
Lynn Haller, Morehead State University
Mary Elizabeth Hannah, University of
Detroit
Jack Hartnett, Virginia Commonwealth
University
Carol Hayes, Delta State University
Karen Hayes, Guilford College
Michael Hillard, Albuquerque TVI
Community College
Peter Hornby, Plattsburgh State
University
Deana Julka, University of Portland
Brian Kelley, Bridgewater College
Sheila Kennison, Oklahoma State
University
Laurel Krautwurst, Blue Ridge
Community College
Judith Levine, Farmingdale State College
Dawn Lewis, Prince George’s
Community College
Deborah Long, East Carolina University
Margaret Lynch, San Francisco State
University
Jean Mandernach, University of
Nebraska, Kearney
Marc Martin, Palm Beach Community
College
Richard Mascolo, El Camino College
Steven Meier, University of Idaho
Nancy Mellucci, Los Angeles
Community College District
Yozan Dirk Mosig, University of
Nebraska
Melinda Myers-Johnson, Humboldt
State University
Michael Nikolakis, Faulkner State
College
Cindy Nordstrom, Southern Illinois
University
Laura O’Sullivan, Florida Gulf Coast
University
Ginger Osborne, Santa Ana College
Vernon Padgett, Rio Hondo College
Jeff Pedroza, Santa Ana College
Laura Phelan, St. John Fisher College
Faye Plascak-Craig, Marian College
Skip Pollock, Mesa Community College
Chris Robin, Madisonville Community
College
Lynne Schmelter-Davis, Brookdale
County College of Monmouth
Mark Shellhammer, Fairmont State
College
Christina Sinisi, Charleston Southern
University
Patricia Stephenson, Miami Dade
College
Mary Ellen Dello Stritto, Western
Oregon University
Mario Sussman, Indiana University of
Pennsylvania
John Teske, Elizabethtown College
Stacy Walker, Kingwood College
Robert Wellman, Fitchburg State
University
Alan Whitlock, University of Idaho
Finally, we offer our thanks to all of the colleagues whose feedback has improved our
book. Thanks also to all instructors of this most-difficult-to-teach course for taking on
the pedagogical challenge and conveying to students their passion about the joys and
relevance of psychological science and practice.
If you have any recommendations of your own that we should not overlook for
the next edition, please write to us! Address your comments to Dr. Robert Johnson,
CoreConcepts7@gmail.com.

A B O U T T H E A U T H O R S
Philip Zimbardo, PhD, Stanford University professor, has been teaching the
introductory psychology course for 50 years and has been writing the basic text for
this course, as well as the faculty guides and student workbooks, for the past 35 years.
In addition, he has helped to develop and update the PBS-TV series, Discovering Psychol-
ogy, which is used in many high school and university courses both nationally and
internationally. He has been called “The Face and Voice of Psychology” because of
this popular series and his other media presentations. Phil also loves to conduct and
publish research on a wide variety of subjects, as well as teach and engage in public
and social service activities. He has published more than 400 professional and popular
articles and chapters, including 50 books of all kinds. He recently published a trade
book on the psychology of evil, The Lucifer Effect, that relates his classic Stanford
Prison Experiment to the abuses at Iraq’s Abu Ghraib Prison. His new book is The
Time Paradox, but his new passion is helping to create wise and effective everyday
heroes as part of his Heroic Imagination Project. Please see these websites for more
information: www.zimbardo.com; www.prisonexp.org; www.PsychologyMatters.org;
www.theTimeParadox.com; www.LuciferEffect.com; www.HeroicImagination.org.
Robert Johnson, PhD, taught introductory psychology for 28 years at Umpqua
Community College. He acquired an interest in cross-cultural psychology during a
Fulbright summer in Thailand, followed by many more trips abroad to Japan, Korea,
Latin America, Britain, and, most recently, to Indonesia. Currently, he is working on a
book on the psychology in Shakespeare. Bob is especially interested in applying psy-
chological principles to the teaching of psychology and in encouraging linkages be-
tween psychology and other disciplines. In keeping with those interests, he founded
the Pacific Northwest Great Teachers Seminar, of which he was the director for
20 years. Bob was also one of the founders of Psychology Teachers at Community
Colleges (PT@CC), serving as its executive committee chair during 2004. That same
year, he also received the Two-Year College Teaching Award given by the Society
for the Teaching of Psychology. Bob has long been active in APA, APS, the Western
Psychological Association, and the Council of Teachers of Undergraduate Psychology.
Vivian McCann, a senior faculty member in psychology at Portland Community
College in Portland, Oregon, teaches a wide variety of courses, including introductory
psychology, human relations, intimate relationships, and social psychology. Born and
raised in the California desert just 10 miles from the Mexican border, she learned
early on the importance of understanding cultural backgrounds and values in effective
communication and in teaching, which laid the foundation for her current interest in
teaching and learning psychology from diverse cultural perspectives. She loves to travel
and learn about people and cultures and to nurture the same passions in her students.
She has led groups of students on four trips abroad, and in her own travels has visited
24 countries so far. Vivian maintains a strong commitment to teaching excellence and
has developed and taught numerous workshops in that area. She has served on the
APA’s Committee for Psychology Teachers at Community Colleges (PT@CC) and is
an active member of the Western Psychological Association and APS. She is also the
author of Human Relations: The Art and Science of Building Effective Relationships.
xxv

www.zimbardo.com

www.prisonexp.org

www.PsychologyMatters.org

www.theTimeParadox.com

www.LuciferEffect.com

www.HeroicImagination.org

Mind, Behavior, and
Psychological Science1
Psychology MattersCore ConceptsKey Questions/Chapter Outline
1.1 What Is Psychology—and What
Is It NOT ?
Psychology: It’s More Than You Think
Psychology Is Not Psychiatry
Thinking Critically about Psychology and
Pseudo-Psychology
Psychology is a broad field with
many specialties, but fundamentally,
psychology is the science of behavior
and mental processes.
Using Psychology to Learn
Psychology
In this book, Key Questions and Core
Concepts help you organize what you
learn.
1.2 What Are Psychology’s Six Main
Perspectives?
Separation of Mind and Body and the
Modern Biological Perspective
The Founding of Scientific Psychology and
the Modern Cognitive Perspective
The Behavioral Perspective: Focusing on
Observable Behavior
The Whole-Person Perspectives:
Psychodynamic, Humanistic, and Trait
and Temperament
The Developmental Perspective: Changes
Arising from Nature and Nurture
The Sociocultural Perspective: The
Individual in Context
The Changing Face of Psychology
Six main viewpoints dominate
modern psychology—the biological,
cognitive, behavioral, whole-person,
developmental, and sociocultural
perspectives—each of which grew out
of radical new concepts about mind
and behavior.
Psychology as a Major
To call yourself a psychologist, you’ll
need graduate training.
Psychologists, like all other scientists,
use the scientific method to test their
ideas empirically.
The Perils of Pseudo-psychology
Critical thinking failures often result in
disastrous consequences.
CHAPTER PROBLEM How would psychology test the claim that sugar makes children hyperactive?
CRITICAL THINKING APPLIED Facilitated Communication
1.3 How Do Psychologists Develop
New Knowledge?
Four Steps in the Scientific Method
Five Types of Psychological Research
Controlling Biases in Psychological Research
Ethical Issues in Psychological Research

3
A FTER THE KIDS HAD ALL THAT SUGAR—THE CAKE, ICE CREAM, PUNCH, and candy—they were absolutely bouncing off the walls!” said one of our friends who was describing a birthday party for her 8-year-old daughter.I must have had a skeptical look on my face, because she stopped her story
short and asked, “You don’t believe it?” Then she added, “You psychologists just don’t believe
in common sense, do you?”
I responded that what people think of as “common sense” can be wrong, reminding her
that common sense once held that Earth was flat. “Perhaps,” I suggested, “it might be wrong
again—this time about the so-called ‘sugar high’ people think they observe.
“It could have been just the excitement of the party,” I added.
“Think they observe?” my friend practically shouted. “Can you prove that sugar doesn’t
make children hyperactive?”
“No,” I said. “Science doesn’t work that way. But what I could do,” I ventured, “is perform
an experiment to test the idea that sugar makes children ‘hyper.’ Then we could see whether
your claim passes or fails the test.”
My timing wasn’t the best for getting her involved in a discussion of scientific experiments,
so let me pose the problem to you.
PROBLEM: How would psychology test the claim that sugar makes children hyperactive?
We invite you to think about how we might set up such an experiment. We could, for example,
give kids a high-sugar drink and see what happens. But because people often see only what
“

4 C H A P T E R 1 Mind, Behavior, and Psychological Science
they expect to see, our expectations about sugar and hyperactivity could easily influence our
observations. So how could we design an experiment about sugar and hyperactivity that also
accounts for our expectations? It is not an easy problem, but we will think it through together,
and by the end of this chapter, you will have the tools you need to solve it.
Every chapter in the book will begin with a problem such as this—a problem aimed at
getting you actively involved in learning psychology and thinking critically about some impor-
tant concepts in the chapter. Solving the problem with us, rather than just passively reading
the words, will make the concepts more meaningful to you and more easily remembered (see
Chapter 5 to find out why).
The important concept illustrated by the “sugar high” problem is one of the most fun-
damental concepts in all of psychology: using the scientific method to explore the mind and
behavior. But before we get into the details of the scientific method, let’s clarify what we mean
by the term psychology itself.
1.1 KEY QUESTION
What Is Psychology—and What Is It NOT?
“I hope you won’t psychoanalyze me,” says the student at the office door. It is a frequent
refrain and an occupational hazard for professors of psychology. But students need not
worry about being psychoanalyzed, for two reasons. First, not all psychologists diagnose
and treat mental problems—in fact, those who do are actually in the minority among pro-
fessors of psychology. Second, only a few psychologists are actually psychoanalysts. The
term psychoanalysis refers to a highly specialized and relatively uncommon form of ther-
apy. You will learn more about the distinction between psychologists and psychoanalysts
later in the chapter—but, in the meantime, don’t fret that your professor will try to find
something wrong with you. In fact, your professor is much more likely to be interested in
helping you learn the material than in looking for signs of psychological disorder.
So, you might wonder, if psychology is not all about mental disorders and therapy,
what is it all about?
The term psychology comes from psyche, the ancient Greek word for “mind,” and
the suffix -ology, meaning “a field of study.” Literally, then, psychology means “the
study of the mind.” Most psychologists, however, use the broader definition given in
our Core Concept for this section of the chapter:
Core Concept 1.1
Psychology is a broad field, with many specialties, but fundamentally
psychology is the science of behavior and mental processes.
One important point to note about this definition: Psychology includes not only
mental processes but also behaviors. In other words, psychology’s domain covers both
internal mental processes that we observe only indirectly (such as thinking, feeling,
and desiring) as well as external, observable behaviors (such as talking, smiling, and
running). A second important part of our definition concerns the scientific compo-
nent of psychology. In brief, the science of psychology is based on objective, verifiable
evidence—not just the opinions of experts and authorities, as we often find in non-
scientific fields. We will give a more complete explanation of the science of psychol-
ogy in the last part of this chapter. For now, though, let’s take a closer look at what
psychologists actually do.
Psychology: It’s More Than You Think
Psychology covers more territory than most people realize. As we have seen, not
all psychologists are therapists. Many work in education, industry, sports, prisons,
psychology The science of behavior and mental
processes.

What Is Psychology—and What Is It NOT? 5
government, churches and temples, private practice, human
relations, advertising, and in the psychology departments of
colleges and universities (see Figure 1.1). Others work for
engineering firms, consulting firms, and the courts (both the
judicial and the NBA variety). In these diverse settings, psy-
chologists perform a wide range of tasks, including teaching,
research, testing, and equipment design—as well as psycho-
therapy. In fact, psychology’s specialties are too numerous
to cover them all here, but we can give you a taste of the
field’s diversity by first dividing psychology into three broad
groups.
Three Ways of Doing Psychology Broadly speaking,
psychologists cluster into three main categories: experi-
mental psychologists, teachers of psychology, and applied
psychologists. Some overlap exists among these groups, how-
ever, because many psychologists take on multiple roles in
their work.
Experimental psychologists (sometimes called research psychologists) constitute
the smallest of the three groups. Nevertheless, they perform most of the research
that creates new psychological knowledge (Frincke & Pate, 2004).1 For example, an
experimental psychologist would be well equipped to study the effects of sugar on
hyperactivity in children. While some experimental psychologists can be found in in-
dustry or private research institutes, the majority work at a college or university, where
most also teach.
Teachers of psychology are traditionally found at colleges and universities, where
their assignments typically involve not only teaching but also research and publica-
tion. Increasingly, however, psychologists can be found at community colleges and
high schools, where their teaching load is higher because these institutions generally
do not require research (American Psychological Association, 2007b; Johnson &
Rudmann, 2004).
Applied psychologists use the knowledge developed by experimental psychologists to
tackle human problems of all kinds, such as toy or equipment design, criminal analy-
sis, and psychological treatment. They work in a wide variety of places, ranging from
schools, clinics, and social service agencies to factories, airports, hospitals, and casinos.
All told, about two-thirds of the doctoral-level psychologists in the United States work
primarily as applied psychologists (Kohout & Wicherski, 2000; Wicherski et al., 2009).
Applied Psychological Specialties Some of the most popular applied specialties
include:
• Industrial and organizational psychologists (often called I/O psychologists)
specialize in personnel selection and in tailoring the work environment to
maximize productivity and morale. They may, for example, create programs to
motivate employees or to improve managers’ leadership skills. I/O psychologists
also conduct market research and examine current issues such as attitudes toward
pregnancy in the workplace (Shrader, 2001).
• Sports psychologists help athletes improve their performance by planning effective
practice sessions, enhancing motivation, and learning to control emotions under
pressure. Some focus exclusively on professional athletes, and others work with
recreational athletes. Sports psychologists may also, for example, study various
types of personalities and their relation to high-risk endeavors such as firefighting,
parachuting, or scuba diving.
1Throughout this book, you will find citations in parentheses, calling your attention to a complete bibliographic
reference found in the References section, beginning on p. R-1, near the end of this book. These brief in-text
citations give the authors’ last names and the publication date. With the complete references in hand, your library
can help you find the original source.
experimental psychologists Psychologists
who do research on basic psychological processes—as
contrasted with applied psychologists. Experimental
psychologists are also called research psychologists.
teachers of psychology Psychologists whose
primary job is teaching, typically in high schools,
colleges, and universities.
applied psychologists Psychologists who use
the knowledge developed by experimental psychologists
to solve human problems.
FIGURE 1.1
Work Settings of Psychologists
Source: 2009 Doctorate Employment Survey, APA Center for Workforce Studies. March
2011.
Independent
practiceOther counseling
sevices
Other educational
settings
Government
Business,
Consulting,
Other
Hospitals and
HMOs
Universities, colleges,
and medical schools
6%
6%
8%
33%21%
15%
11%
Read
MyPsychLab
about I/O Psychology at

6 C H A P T E R 1 Mind, Behavior, and Psychological Science
• School psychologists are experts in teaching and learning.
They deal with issues impacting learning, family or personal
crises influencing school performance, or social conditions
such as gangs, teen pregnancy, or substance abuse. They
sometimes diagnose learning or behavioral problems and
work with teachers, students, and parents to help students
succeed in school. Many school psychologists work for
school districts, where their work includes administering,
scoring, and interpreting psychological tests.
• Clinical and counseling psychologists help people improve
social and emotional adjustment or work through difficult
choices in relationships, careers, or education. Almost half
of all doctoral-level psychologists list clinical or counseling
psychology as their specialty (Wichersky et al., 2009).
• Forensic psychologists provide psychological expertise to the
legal and judicial system. One of the most recently recognized
specialties in psychology, forensic psychology has gained
rapid popularity due in part to such TV shows as
Criminal Minds, Profiler, and CSI. And, while a real day in the life of forensic
psychologists may not be as glamorous or fast paced as their television counter-
parts, the field is burgeoning with opportunities. Forensic psychologists may test
inmates in prisons or forensic hospitals to determine readiness for release or fitness
to stand trial, evaluate testimony in cases of rape or child abuse, or help with jury
selection (Clay, 2009; Huss, 2001).
• Environmental psychologists aim to improve human interaction with our envi-
ronment. They may, for example, study the impact of inner-city garden spaces on
children’s academic performance or determine how best to encourage environmen-
tally friendly behavior such as recycling. In private practice, environmental psy-
chologists sometimes help clients maintain their commitment to sustainability or
conduct workshops teaching people the mental health benefits of interacting with
nature (Novotney, 2009).
More information on career possibilities in psychology can be found in Careers in
Psychology for the Twenty-First Century, published by the American Psychological
Association (2003a) and available online at www.apa.org/careers/resources/guides/
careers .
Psychology Is Not Psychiatry
Just as beginning psychology students may think all psychologists are clinical psychol-
ogists, they also may not know the distinction between psychology and psychiatry. So
let’s clear up that confusion, just in case you encounter a test question on the topic.
Virtually all psychiatrists, but only some psychologists, treat mental disorders—and
there the resemblance ends. Psychiatry is a medical specialty, not part of psychology at
all. Psychiatrists hold MD (Doctor of Medicine) degrees and, in addition, have special-
ized training in the treatment of mental and behavioral problems, typically with drugs.
Therefore, psychiatrists are licensed to prescribe medicines and perform other medical
procedures. Consequently, psychiatrists tend to treat patients with more severe mental
disorders (such as schizophrenia) and also to view patients from a medical perspective,
as persons with mental “diseases.”
By contrast, psychology is a much broader field that encompasses the whole range
of human behavior and mental processes, from brain function to social interaction and
from mental well-being to mental disorder. For most psychologists, graduate training
emphasizes research methods, along with advanced study in a specialty such as those
listed earlier. Moreover, while psychologists usually hold doctoral degrees, their train-
ing is not usually medical training, and thus they are not generally licensed to prescribe
medications (Carlat, 2010; Practice Directorate Staff, 2005). Psychologists, then, work
C O N N E C T I O N CHAPTER 13
Clinical psychologists help
people deal with mental
disorders and other psychological
problems (p. 558).
psychiatry A medical specialty dealing with the
diagnosis and treatment of mental disorders.
Applying psychological principles of learning and motivation, sports
psychologists work with athletes to improve performance.
Explore the Concept Psychologists at
Work at MyPsychLab

www.apa.org/careers/resources/guides/careers

What Is Psychology—and What Is It NOT? 7
in a wide variety of fields, all of which view people
from a psychological perspective. This perspective is il-
lustrated by clinical and counseling psychologists, who
are likely to view the people they are helping as clients
rather than patients.
So, now you know that psychiatry is not psychol-
ogy. Next, we’ll look at something else that often gets
confused with psychology: pseudo-psychology.
Thinking Critically about Psychology
and Pseudo-Psychology
TV series like Medium and Supernatural continue a
long tradition of programs that play on people’s fasci-
nation with claims of mysterious powers of the mind
and supernatural influences on our personalities. Your
daily horoscope does the same thing—never mind that
astrology has been thoroughly debunked (Schick &
Vaughn, 2001). Neither is there any factual basis for
graphology (the bogus science of handwriting analysis),
fortune telling, or the supposed power of subliminal messages to influence our behavior.
All these fall under the heading of pseudo-psychology: unsupported psychological beliefs
masquerading as scientific truth.
Certainly horoscopes and paranormal claims can be fun as pure entertainment, but
it is important to know where fact-based reality ends and imagination-based fantasy
begins. After all, you wouldn’t want to stake an important decision about your health
or welfare on false information, would you? Thus, one of the goals of this text is
to help you think critically when you hear extraordinary claims about behavior and
mental processes.
What Is Critical Thinking? Those who talk about critical thinking often find them-
selves in the position of Supreme Court Justice Potter Stewart, who famously was
unable to define pornography but concluded, “I know it when I see it.” Like Justice
Stewart, your fearless authors (Phil, Bob, and Vivian) cannot offer a definition of criti-
cal thinking with which everyone will agree. Nevertheless, we are willing to jump
into the fray with a list of six critical thinking skills we wish to emphasize in this text.
Each is based on a specific question we believe should be asked when confronting new
ideas.
1. What is the source? Does the person making the claim have real expertise in the
field? Suppose, for example, you hear a newscast on which a politician or pundit
declares that juvenile lawbreakers can be “scared straight.” The story explains that,
in the program, first-time offenders receive near-abusive treatment from felons who
try to scare them away from a life of crime with tales of harsh prison life. Such
programs have, in fact, been tried in several states (Finckenauer et al., 1999). But
does the person making the claim have any real knowledge of the subject? Does
the claimant have legitimate credentials, or is he or she merely a self-proclaimed
“expert?” One way to find out is to go online and examine the individual’s ref-
erences and standing within the field. Also, find out whether the source has
something substantial to gain from the claim. If it’s a medical breakthrough, for
example, does the claimant stand to make money from a new drug or medical
device? In the case of a “scared straight” program, is the source trying to score
political points or get votes?
2. Is the claim reasonable or extreme? Life is too short to be critical of everything,
of course, so the trick is to be selective. How? As the famous astronomer Carl
Sagan once said about reports of alien abductions, “Extraordinary claims require
extraordinary evidence” (Nova Online, 1996). Critical thinkers, then, are skeptical
pseudo-psychology Erroneous assertions or
practices set forth as being scientific psychology.
critical thinking skills This book emphasizes
six critical thinking skills, based on the following ques-
tions: What is the source? Is the claim reasonable or
extreme? What is the evidence? Could bias contaminate
the conclusion? Does the reasoning avoid common
fallacies? Does the issue require multiple perspectives?
Fortune tellers, astrologers, and other practitioners of pseudo-psychology
don’t bother to verify their claims with careful research—nor do their clients
engage in critical thinking about such practices.

8 C H A P T E R 1 Mind, Behavior, and Psychological Science
of claims touted as “breakthroughs” or “revolutionary.” Certainly, there are
occasionally breakthroughs or revolutionary new treatments that work—but they
are relatively rare. Most new scientific developments are extensions of existing
knowledge. So, claims that conflict with well-established knowledge should raise a
red flag. For example, beware of ads that promise to help you quit smoking or lose
weight with little or no effort. In the case of “scared straight” programs or any
other quick fix for a difficult problem, remember that simple solutions to complex
problems rarely exist.
3. What is the evidence? This is one of the most important guidelines to critical think-
ing, and you will learn more about what constitutes scientific evidence in the last
section of this chapter. For now, though, beware of anecdotal evidence or testimoni-
als proclaiming the dramatic effects of a new program. These first-hand accounts
tend to be quite convincing, so they often lure us into believing them. Testimonials
and anecdotes, though—no matter how compelling—are not scientific evidence.
They merely represent the experiences of a few carefully selected individuals. It
would be risky, and perhaps even dangerous, to assume that what seems true for
some people must also be true for everyone.
What does the evidence say about “scared straight” programs? Not only do
they not work, but they can also actually inoculate juveniles against fears about
prison. Surprising as it may seem, the hard evidence indicates that teens exposed to
such treatments, on average, subsequently get into more trouble than do those not
given the “scared straight” treatment (Petrosino et al., 2003).
4. Could bias contaminate the conclusion? Critical thinkers know the conditions
under which biases are likely to occur and can recognize common types of bias
we will examine in this chapter. For example, they would question whether medi-
cal researchers who are involved in assessing new drugs can truly remain unbiased
if they are receiving money from the companies whose drugs they are testing
(McCook, 2006).
The form of bias most applicable to our “scared straight” example is
emotional bias: People not only fear crime and criminals but also are often in
favor of harsh treatments for criminal behavior, as evidenced by the recent spate
of “three strikes” laws (which mandate a lifetime in prison after three felony
convictions). Accordingly, the “scared straight” approach may appeal to people
simply because of its harshness. Also, people with a loved one who has gotten
into some trouble may be especially vulnerable to promises of easy reform: Their
desire for help can interfere with clear thinking.
Another common form of bias is confirmation bias, the all-too-human ten-
dency to remember events that confirm our beliefs and ignore or forget contra-
dictory evidence (Halpern, 2002; Nickerson, 1998). For example, confirmation
bias explains why people persist in their beliefs that astrology works: They
remember the predictions that seemed accurate and forget the ones that missed
the mark. Confirmation bias also explains why gamblers have better recollections
for their wins than for their losses, or why we persist in thinking a particular
object is our lucky charm. Amazingly, recent research reveals this bias may be
partly biological in nature. In a study done before a recent presidential election,
people listened to their favorite politicians making statements that contradicted
themselves. Upon hearing the contradictory statement, brain circuits associated
with reasoning in the listeners suddenly shut down, while brain regions most in-
volved with emotion remained active (Shermer, 2006; Westen et al., 2006). It was
as though the brain was saying, “I don’t want to hear anything that conflicts with
my beliefs.” Thus, we may have to exert extra effort and diligence to overcome
this bias.
5. Does the reasoning avoid common fallacies? We will study several common logical
fallacies in this book, but the one most applicable to the “scared straight” example
is the assumption that common sense is a substitute for scientific evidence. In fact,
emotional bias The tendency to make judgments
based on attitudes and feelings, rather than on the
basis of a rational analysis of the evidence.
confirmation bias The tendency to attend to
evidence that complements and confirms our beliefs or
expectations, while ignoring evidence that does not.
anecdotal evidence First-hand accounts
that vividly describe the experiences of one or a few
people, but may erroneously be assumed to be
scientific evidence.

What Is Psychology—and What Is It NOT? 9
in many cases there exists common sense to support both sides of an issue. For
example, we hear that “Birds of a feather flock together”—but we also hear that
“Opposites attract.” Similarly, we are told that “The early bird gets the worm,”
but aren’t we also cautioned that “Haste makes waste?” Which, then, is true? Only
an examination of the evidence can reliably provide the answer. Stay tuned later
in this chapter, and in Chapter 6, for other common fallacies that derail critical
thinking.
6. Does the issue require multiple perspectives? The “scared straight” intervention
makes the simplistic assumption that fear of punishment is the best deterrent
to delinquency, so inducing fear will prevent delinquency. A more sophisticated
view sees delinquency as a complex problem that demands scrutiny from several
perspectives. Psychologists, for example, may look at delinquency from the stand-
points of learning, social influence, or personality traits. Economists would be
interested in the financial incentives for delinquency. And sociologists would focus
on such things as gangs, poverty, and community structures. Surely such a multi-
faceted problem will require a more complex solution than a threatening program.
Thinking Critically about the Chapter Problem How would you apply these criti-
cal thinking guidelines to the chapter-opening problem about whether sugar makes
children hyperactive? First, consider the source: Is the mother of an 8-year-old an ex-
pert on biological effects of sugar? Assuming she is not, you’d have to wonder if the
source of her belief is a reliable one or if she is just repeating some “common sense”
she’s often heard but never questioned. Second, examine the evidence: Have scientific
tests been conducted to measure the effects of sugar on children? Third, could any bi-
ases be at work? For example, if we expect children to be hyperactive after consuming
sugar, that is likely what we will observe. Fourth, is the claimant avoiding common
fallacies in reasoning? In this case, even if we can prove that kids who consume more
sugar are more hyperactive, we can’t be sure that sugar is the cause: Alternatively, per-
haps kids who are already hyperactive eat more sugar as a means of maintaining their
high need for activity. Finally, we should recognize that there are probably other rea-
sons kids get excited at parties. We will explore some of these competing perspectives
in the second section of this chapter.
You may have seen the “scared straight”
issue parodied on the TV show Saturday
Night Live.

10 C H A P T E R 1 Mind, Behavior, and Psychological Science
PSYCHOLOGY MATTERS
Using Psychology to Learn Psychology
Throughout this book, we show you how to use psychology to learn psychology. For
example, we have built in learning tools to help you construct a mental map (sometimes
called a cognitive map or concept map) of every chapter, which is guaranteed to make
your studying of psychology easier. Among the most important are the numbered Key
Questions and Core Concepts. And in MyPsychLab, you will find a tool specially de-
signed to help you to construct concept maps of each chapter.
The Key Questions, which act as the main headings in each chapter, give you a
“heads up” by signaling what to watch for as you read. For example, Key Ques-
tion 1.1 for this section of the chapter asked, WHAT IS PSYCHOLOGY—AND
WHAT IS IT NOT? This tells you this section will define psychology and make
some distinctions between psychology and other fields with which it may be con-
fused or overlap. You are much more likely to remember new concepts if you ap-
proach them with an appropriate Key Question in mind (Glaser, 1990). You can
also use the Key Question to check your understanding of each section before an
exam. If you have a study partner, try asking each other to give detailed answers
to the Key Questions.
PSYCHOLOGICAL SCIENCE OR PSYCHOBABBLE?
Now, let’s put a sampling of your psycho-
logical beliefs to the test. Some of the
following statements are true, and some
are false. Don’t worry if you get a few—or
all—of the items wrong: You will have lots
of company. The point is that what so-
called common sense teaches us about
psychological processes may not withstand
the scrutiny of a scientific test. Mark each
of the following statements as “true” or
“false.” (The answers are given at the end.)
1. _________ It is a myth that most people
use only about 10% of their brains.
2. _________ During your most vivid
dreams, your body may be paralyzed.
3. _________ Psychological stress can
cause physical illness.
4. _________ The color red exists only as
a sensation in the brain. There is no
“red” in the world outside the brain.
5. _________ Bipolar (manic–depressive)
disorder is caused by a conflict in the
unconscious mind.
6. _________ The newborn child’s mind
is essentially a “blank slate” on which
everything he or she will know must be
“written” (learned) by experience.
7. _________ Everything that happens to us
leaves a permanent record in memory.
8. _________ You were born with all the
brain cells that you will ever have.
9. _________ Intelligence is a nearly pure
genetic trait that is fixed at the same
level throughout a person’s life.
10. _________ Polygraph (“lie detector”)
devices are remarkably accurate in
detecting physical responses that, in
the eye of a trained examiner, reliably
indicate when a suspect is lying.
Answers The first four items are true; the rest
are false. Here are some brief explanations
for each item; you will find more detail in the
chapters indicated in parentheses. 1. True:
This is a myth. We use all parts of our brains
every day. (See Chapter 2, “Biopsychology,
Neuroscience, and Human Nature.”)
2. True: During our most vivid dreams, which
occur during rapid eye movement sleep
(REM), the voluntary muscles in our body
are paralyzed, with the exception of those
controlling our eyes. (See Chapter 8, “States
of Consciousness.”) 3. True: The link between
mind and body can make you sick when you
are under chronic stress. (See Chapter 14,
“From Stress to Health and Well-Being.”)
4. True: Strange as it may seem, all sensations
of color are created in the brain itself. Light
waves do have different frequencies, but they
have no color. The brain interprets the various
frequencies of light as different colors. (See
Chapter 3, “Sensation and Perception.”)
5. False: There is no evidence at all that
unconscious conflicts play a role in bipolar
disorder. Instead, the evidence suggests a
strong biochemical component. The disorder
usually responds well to certain drugs, hinting
that it involves faulty brain chemistry. Research
also suggests that this faulty chemistry
may have a genetic basis. (See Chapter 12,
“Psychological Disorders,” and Chapter 13,
“Therapies for Psychological Disorders.”)
6. False: Far from being a “blank slate,” the
newborn child has a large repertoire of built-in
abilities and protective reflexes. The “blank
slate” myth also ignores the child’s genetic
potential. (See Chapter 7, “Development
over the Lifespan.”) 7. False: Although many
details of our lives are remembered, there is no
evidence that memory records all the details
of our lives. In fact, we have good reason to
believe that most of the information around
us never reaches memory and that what does
reach memory often becomes distorted. (See
Chapter 5, “Memory.”) 8. False: Contrary to
what scientists thought just a few years ago,
some parts of the brain continue to create
new cells throughout life. (See Chapter 2,
“Biopsychology, Neuroscience, and Human
Nature.”) 9. False: Intelligence is the result
of both heredity and environment. Because it
depends, in part, on environment, your level
of intelligence (as measured by an IQ test) can
change throughout your life. (See Chapter 6,
“Thinking and Intelligence.”) 10. False: Even
the most expert polygrapher can incorrectly
classify a truth-teller as a liar or fail to identify
someone who is lying. Objective evidence
supporting the accuracy of lie detectors is
meager. (See Chapter 9, “Motivation and
Emotion.”)
Map the Concepts at
MyPsychLab

What Are Psychology’s Six Main Perspectives? 11
Think of Core Concepts as brief answers to the Key Questions. (In fact, each one is
numbered to match its Key Question.) In other words, a Core Concept highlights the
central idea in each section—much like a preview at the movies. Recognize, though,
that a Core Concept is not a complete answer but rather a capsule summary of ideas to
be fleshed out. For example, the Core Concept for this section says:
Psychology is a broad field with many specialties, but fundamentally,
psychology is the science of behavior and mental processes.
This alerts you to the two important ideas in this section: (1) psychology studies both
the mind and behavior, and (2) there is a variety of specialties within psychology.
Knowing these overarching themes will help you find the important ideas and organize
them in your mind.
After you have constructed the foundation of your mental map with the overarch-
ing themes, fill in the details using the boldfaced terms in that section so your map
shows how each term fits into the theme. For example, can you explain the differ-
ence between applied, experimental, and teaching psychologists? Between psychology,
psychiatry, and pseudo-psychology?
In summary, then, Key Questions and Core Concepts lead you to the big ideas in
the chapter and provide a framework for the various concepts in that chapter. They
will help you step back from the details to see meaningful patterns—as the saying
goes—to distinguish the forest from the trees (and consequently, to understand how all
the trees fit into the forest).
1.2 KEY QUESTION
What Are Psychology’s Six Main Perspectives?
The shape of modern psychology has been molded by its history, which dates back
some 25 centuries to the Greek philosophers Socrates, Plato, and Aristotle. These
sages not only speculated about consciousness and madness; they also knew that emo-
tions could distort thinking and that our perceptions are merely interpretations of the
external world. Even today, people would probably agree with many of these ancient
conjectures—and so would modern psychology.
The Greeks, however, get only partial credit for laying the foundations of psychol-
ogy. At roughly the same time, Asian and African societies were developing their own
Check Your Understanding
1. RECALL: In what way is modern psychology’s scope broader than
the Greek concept of psyche?
2. RECALL: Name two types of applied psychologists.
3. TRUE OR FALSE: Most psychologists are therapists.
4. APPLICATION: Which critical thinking questions discussed
in this section would be most applicable to the argument
that harsher sentences are the best way of dealing with crime
because “punishment is the only language that criminals
understand”?
5. UNDERSTANDING THE CORE CONCEPT: How is psychology
different from psychiatry and other disciplines that deal with
people?
Answers 1. Modern psychology studies behavior as well as the mind. 2. There are many sorts of applied psychologists. The ones mentioned in
this chapter are I/O psychologists, sports psychologists, school psychologists, clinical and counseling psychologists, forensic psychologists, and
environmental psychologists. 3. False. 4. Probably the most applicable for this claim would be these: “What is the evidence?” and “Could bias
contaminate the conclusion?” But we wouldn’t disagree with any other questions you may have listed because, just as with the “scared straight”
issue, they could all apply to a critical analysis of the claim. 5. Psychology is a broader field, covering all aspects of behavior and mental processes.
Study and Review at MyPsychLab

12 C H A P T E R 1 Mind, Behavior, and Psychological Science
psychological ideas. In Asia, followers of yoga and Buddhism were exploring conscious-
ness, which they attempted to control with meditation. Meanwhile, in Africa, other ex-
planations for personality and mental disorders were emerging from traditional spiritual
beliefs (Berry et al., 1992). Based on these folk psychologies, shamans (healers) devel-
oped therapies rivaling the effectiveness of treatments used in psychology and psychiatry
today (Lambo, 1978). It was, however, the Greek tradition and, later, the Church that
most influenced the winding developmental path of Western psychology as a science.
What role did the Church play in shaping the study of psychology? During medieval
centuries, for example, clerics actively suppressed inquiry into human nature, partly in
an attempt to discourage interest in the “world of the flesh.” For medieval Christians,
the human mind and soul were inseparable and—like the mind of God—presented a
mystery that mortals should never try to solve.
Change of this entrenched viewpoint did not come easily. It took a series of radi-
cal new ideas, spaced over several hundred years, to break the medieval mindset and
lay the intellectual foundation for modern psychology—which brings us to our Core
Concept for this section:
Core Concept 1.2
Six main viewpoints dominate modern psychology—the biological,
cognitive, behavioral, whole-person, developmental, and sociocultural
perspectives—each of which grew out of radical new concepts about
mind and behavior.
As we examine these perspectives, you will see that each viewpoint offers its own
unique explanation for human behavior. Taken together, they comprise psychology’s
multiple perspectives, each of which will become an important tool in your “psychol-
ogy toolbox” for understanding human behavior. To help you see for yourself how
useful these perspectives can be, we will apply each one to a problem with which many
students struggle: procrastination. Let’s begin with the biological perspective.
Separation of Mind and Body and the Modern Biological Perspective
The 17th-century philosopher René Descartes (Day-CART) proposed the first radi-
cal new concept that eventually led to modern psychology: a distinction between
the spiritual mind and the physical body. The genius of Descartes’ insight was that it
allowed the Church to keep the mind off limits for scientific inquiry, while simultane-
ously permitting the study of human sensations and behaviors because they were based
on physical activity in the nervous system. His proposal fit well with exciting new
discoveries about biology, in which scientists had just learned how the sense organs
of animals convert stimulation into nerve impulses and muscular responses. Such dis-
coveries, when combined with Descartes’ separation of mind and body, allowed scien-
tists to demonstrate that biological processes, rather than mysterious spiritual forces,
caused sensations and simple reflexive behaviors.
The Modern Biological Perspective Four hundred years later, Descartes’ revolu-
tionary perspective provides the basis for the modern biological perspective. No lon-
ger constrained by the dictates of the medieval Church, however, modern biological
psychologists have rejoined mind and body (although they leave issues of the soul to
religion), and now view the mind as a product of the brain.
In this current view, our personalities, preferences, behavior patterns, and abilities
all stem from our physical makeup. Accordingly, biological psychologists search for
the causes of our behavior in the brain, the nervous system, the endocrine (hormone)
system, and the genes. Procrastination, from this perspective, may result from a certain
type of brain chemistry (Liu, 2004), which could be inherited. While they don’t deny
the value of other perspectives on mind and behavior, biological psychologists aim to
learn as much as possible about the physical underpinnings of psychological processes.
biological perspective The psychological
perspective that searches for the causes of behavior in
the functioning of genes, the brain and nervous system,
and the endocrine (hormone) system.

What Are Psychology’s Six Main Perspectives? 13
Two Variations on the Biological Theme As you might imagine, the biological
view has strong roots in medicine and biological science. In fact, the emerging field of
neuroscience combines biological psychology with biology, neurology, and other disci-
plines interested in brain processes. Thanks to spectacular advances in computers and
brain-imaging techniques, neuroscience is a hot area of research. Among their achieve-
ments, neuroscientists have learned how damage to certain parts of the brain can destroy
specific abilities, such as speech, social skills, or memory. And, as we will see in Chapter 8,
they now use brain wave patterns to open up the hidden world of sleep and dreams.
Another important variant of biological psychology sprouted recently from ideas
proposed by Charles Darwin some 150 years ago. This new evolutionary psychology
holds that much human behavior arises from inherited tendencies, and it has gained a
substantial boost from the recent surge of genetics research. In the evolutionary view,
our genetic makeup—underlying our most deeply ingrained behaviors—was shaped by
conditions our remote ancestors faced thousands of years ago.
According to evolutionary psychology, environmental forces have pruned the
human family tree, favoring the survival and reproduction of individuals with the most
adaptive mental and physical characteristics. Darwin called this process natural selec-
tion. Through it, the physical characteristics of our species have evolved (changed) in
the direction of characteristics that gave the fittest organisms a competitive advantage.
Some proponents of evolutionary psychology have made highly controversial
claims. In their view, even the most undesirable human behaviors, such as warfare,
rape, and infanticide, may have grown out of biological tendencies that once helped
humans adapt and survive (Buss, 2008). This approach also proposes controversial
biological explanations for certain gender differences—why, for instance, men typically
have more sexual partners than do women. Stay tuned for more of this controversy in
our discussion of sexuality in Chapter 9.
The Founding of Scientific Psychology
and the Modern Cognitive Perspective
Another radical idea that shaped the early
science of psychology came from chem-
istry, where scientists had developed the
famous periodic table after noticing pat-
terns in properties of the chemical elements.
At one stroke, the periodic table made the
relationships among the elements clear. Wil-
helm Wundt, a German scientist (who, incidentally,
became the first person to call himself a “psychologist”) wondered if he could sim-
plify the human psyche in the same way the periodic table had simplified chemistry.
Perhaps he could discover “the elements of conscious experience”! Although Wundt
never realized his dream of a periodic table for the mind, he did have this break-
through insight: The methods of science used to objectively measure and study the
natural world, such as in chemistry or physics, could be used to study the mind and
body as well.
Introspecting for the Elements of Conscious Experience “Please press the button
as soon as you see the light,” Professor Wundt might have said, as he readied to record
the reaction time between the light stimulus and a student’s response. Such simple
yet concrete experiments were common fare in 1879 in the world’s first psychology
laboratory at the University of Leipzig. There, Wundt and his students also performed
studies in which trained volunteers described their sensory and emotional responses
to various stimuli, using a technique called introspection. These were history’s first
psychology experiments: studies of what Wundt and his students proposed to be
the basic “elements” of consciousness, including sensation and perception, memory,
attention, emotion, thinking, learning, and language. All our mental activity, they
asserted, consists of different combinations of these basic processes.
neuroscience The field devoted to understanding
how the brain creates thoughts, feelings, motives, con-
sciousness, memories, and other mental processes.
evolutionary psychology A relatively new
specialty in psychology that sees behavior and mental
processes in terms of their genetic adaptations for
survival and reproduction.
introspection The process of reporting on one’s
own conscious mental experiences.
The periodic table of the chemical
elements inspired Wilhelm Wundt to
consider how the human mind might be
broken down into a similar framework of
common elements.
Table of
ELEMENTS OF CONSCIOUS EXPERIEN
Attention Perception Memory
Emotion Sensation Thinking

14 C H A P T E R 1 Mind, Behavior, and Psychological Science
Wundt’s Legacy: Structuralism Wundt’s pupil, Edward Bradford Titchener,
brought the quest for the elements of consciousness to America, where Titchener be-
gan calling it structuralism. Titchener’s term was fitting, because his goal—like that
of Wundt—was to reveal the most basic “structures” or components of the mind
(Fancher, 1979). So, even though Wundt never used the term, he is considered the
father of structuralism.
From the outset, both Wundt and Titchener became magnets for critics. Objections
especially targeted the introspective method as being too subjective. After all, said the
critics, how can we judge the accuracy of people’s descriptions of their thoughts and
feelings?
But Wundt and Titchener have had the last laugh. Even though psychologists some-
times view their ideas as quaint, they still rely on updated versions of the old structur-
alist methods. For example, you will see introspection at work when we study sleep
and dreaming, and you can experience it firsthand in the upcoming Do It Yourself!
box. Further, we can guess that Wundt and Titchener, if they were alive
today, would still be laughing for one more reason: The topics they first
identified and explored can be found as chapter headings in every intro-
ductory psychology text—including this one.
James and the Function of Mind and Behavior One of Wundt’s
most vocal critics, the American psychologist William James, argued
that the German’s approach was far too narrow. (James also said
it was boring—which didn’t help his already strained relationship
with Wundt.) Psychology should include the function of conscious-
ness, not just its structure, James argued. Appropriately, his brand
of psychology led to a “school”2 that became known as functionalism
(Fancher, 1979).
James and his followers found Charles Darwin’s ideas far more
interesting than Wundt’s. Like Darwin, James had a deep interest in
emotion that included its relation to the body and behavior (not just
as an element of consciousness, as in Wundt’s system). He also liked
structuralism A historical school of psychology
devoted to uncovering the basic structures that make
up mind and thought. Structuralists sought the
“elements” of conscious experience.
2The term school refers to a group of thinkers who share the same core beliefs.
functionalism A historical school of psychology
that believed mental processes could best be under-
stood in terms of their adaptive purpose and function.
For such demonstrations, the Gestalt
psychologists borrowed Wundt’s method
of introspection, but they objected to his
emphasis on the parts, or “elements,”
of consciousness. Instead, the Gestalt
psychologists sought to understand how
we construct “perceptual wholes,” or
Gestalts. How do we, for example, form
the perception of a face from its compo-
nent lines, shapes, colors, and textures?
Their ultimate goal was even grander:
They believed that understanding percep-
tion would lead them to an understanding
of how the brain creates perceptions. You
will get to know the Gestalt psychologists
better in Chapter 3, when we take an
in-depth look at sensation and perception.
A DEMONSTRATION FROM GESTALT PSYCHOLOGY
Without reading further, decide quickly which
one of the two figures above (see Figure 1.2)
you would name “Takete” and which you
would call “Maluma.” You might want to see
if your friends give the same answer.
According to an
early 20th-century group
of German psychologists,
known as the Gestalt
psychologists, the names
you give to these figures
may reflect the asso-
ciations wired into your
brain. Indeed, most peo-
ple think that the soft-
sounding term Maluma is more appropriate
for the rounded left-hand figure, while the
sharp-sounding term Takete better fits the
pointy figure on the right (Köhler, 1947).
This was just one of many simple tests they
developed in their quest to understand how
we perceive our world.
FIGURE 1.2
Takete or Maluma?
Cognitive psychologist Elizabeth Loftus has done
pioneering studies showing the fallibility of memory
and eyewitness testimony.

What Are Psychology’s Six Main Perspectives? 15
Darwin’s emphasis on organisms adapting to their environments. James therefore
proposed that psychology should explain how people adapt—or fail to adapt—to
the real world outside the laboratory.
The functionalists, then, became the first applied psychologists— examining how
psychology could be used to improve human life. James himself wrote extensively on
the development of learned “habits,” the psychology of religion, and teaching. He is
also thought to be the first American professor ever to ask for student evaluations
(Fancher, 1979). His follower, John Dewey, founded the “progressive education” move-
ment, which emphasized learning by doing rather than by merely listening to lectures
and memorizing facts.
Introspection was the point on which structuralism and functionalism agreed.
Ironically, their point of agreement was also their greatest point of vulnerability: The
introspective method was subjective, leaving them vulnerable to criticism that their
versions of psychology were not really scientific. Overcoming this problem took more
than half a century and the cooperation of experts from several disciplines who came
together to form the cognitive perspective.
The Modern Cognitive Perspective The development of the computer—which
became the new metaphor for the mind—gave psychology an irresistible push to-
ward a new synthesis: the modern cognitive perspective. Following in the tradition
of its structuralist, functionalist, and Gestalt ancestors, this perspective emphasizes
cognition, or mental activity, such as perceptions, interpretations, expectations,
beliefs, and memories. From this viewpoint, a person’s thoughts and actions are
the result of the unique cognitive pattern of perceptions and interpretations of her
experiences.
Today, however, the cognitive perspective boasts more objective methods of
observation than its forebears, thanks to stunning advancements in brain-imaging
techniques that allow scientists to view the brain as it engages in various mental
processes.
cognitive perspective Another of the main
psychological viewpoints distinguished by an empha-
sis on mental processes, such as learning, memory,
perception, and thinking, as forms of information
processing.
AN INTROSPECTIVE LOOK AT THE NECKER CUBE
The cube in Figure 1.3A will trick your
eye—or, more accurately, it will trick your
brain. Look at the cube for a few moments,
and suddenly it will seem to change per-
spectives. For a time it may seem as if you
were viewing the cube from the upper right
(see Figure 1.3B). Then, abruptly, it will
shift and appear as though you were seeing
it from the lower left (see Figure 1.3C).
It may take a little time for the cube
to shift the first time. But once you see
it change, you won’t be able to prevent
it from alternating back and forth, seem-
ingly at random. Try showing the cube to
a few friends and asking them what they
see. Do they see it shifting perspectives,
as you do?
This phenomenon was not discovered
by a psychologist. Rather, Louis Necker, a
Swiss geologist, first noticed it nearly 200
years ago while looking at cube-shaped
crystals under a microscope. Necker’s
amazing cube illustrates two important
points.
First, it illustrates the much-
maligned process of introspection,
pioneered by Wundt and his students.
You will note that the only way we can
demonstrate that the Necker cube
changes perspectives in our minds is
by introspection: having people look at
the cube and report what they see. And
why is this important to psychology?
Only the most hard-core behaviorists
would deny that something happens
mentally within a person looking at
the cube. In fact, the Necker cube
demonstrates that we add meaning to
our sensations—a process called per-
ception, which will be a main focus of
Chapter 3.
The second important point is this:
The Necker cube can serve as a metaphor
for the multiple perspectives in psychol-
ogy. Just as there is no single right way
to see the cube, there is no single per-
spective in psychology that gives us the
whole “truth” about behavior and mental
processes. Put another way, if we are to
understand psychology fully, we must alter-
nately shift our viewpoints among multiple
perspectives.
A
B C
FIGURE 1.3
Different Perspectives of the Necker Cube
Necker cube An ambiguous two-dimensional
figure of a cube that can be seen from different per-
spectives: The Necker cube is used here to illustrate
the notion that there is no single “right way” to view
psychological processes.

16 C H A P T E R 1 Mind, Behavior, and Psychological Science
How would cognitive psychologists explain procrastination? First, they might
point out that procrastinators often underestimate how long a project might take—
illustrating the role of cognitive expectations in our behavior patterns. Also, procrastina-
tors may be victims of confirmation bias if they remember the times they previously pro-
crastinated yet completed a project on time, while forgetting the deadlines they missed.
Finally, people who put things off until the last minute may not interpret their behav-
ior as a problem—perhaps they tell themselves they do their best work under pressure.
In all these ways, cognitive psychology sheds light on the internal thinking processes
that influence procrastination and other human behaviors.
The Behavioral Perspective: Focusing on Observable Behavior
Early in the 1900s, a particularly radical and feisty group, known as the behavior-
ists, made a name for themselves by disagreeing with nearly everyone. Most famously,
they proposed the idea that the mind should not be part of psychology at all! John B.
Watson, an early leader of the behaviorist movement, argued that a truly objective sci-
ence of psychology should deal solely with observable events: physical stimuli from the
environment and the organism’s overt responses. Behaviorism, said Watson, is the sci-
ence of behavior and the measurable environmental conditions that influence it (refer
to Table 1.1).
Why did behaviorists reject mental processes—such as introspection—as a viable
area of scientific study? B. F. Skinner, another influential behaviorist, may have best
summarized this perspective when he suggested that the seductive concept of “mind”
behaviorism A historical school (as well as a
modern perspective) that has sought to make psychol-
ogy an objective science by focusing only on
behavior—to the exclusion of mental processes.
TABLE 1.1 Psychology’s Six Perspectives
Perspective What Determines Behavior? Sources
Biological perspective The brain, nervous system,
endocrine system (hormones),
and genes.
Rene Descartes
Cognitive perspective A person’s unique pattern of
perceptions, interpretations,
expectations, beliefs, and
memories.
Wilhelm Wundt and William
James
Behavioral perspective The stimuli in our environment,
and the previous consequences
of our behaviors.
John Watson and B.F. Skinner
Whole-person perspective Psychodynamic: Processes in
our unconscious mind.
Humanistic: Our innate needs
to grow, and to fulfill our best
possible potential.
Trait and temperament: Unique
personality characteristics
that are consistent over time
and across situations.
Sigmund Freud
Carl Rogers and Abraham
Maslow
Ancient Greeks
Developmental perspective The interaction of heredity and
environment, which unfolds in
predictable patterns through
the lifespan.
Mary Ainsworth, Jean Piaget
Sociocultural perspective The power of the situation.
Social and cultural influences
can overpower the influence of
all other factors in determining
behavior.
Stanley Milgram, Philip
Zimbardo
C O N N E C T I O N CHAPTER 2
Brain scanning methods such
as CT, PET, MRI, and fMRI use
advanced computer technology
to see into the brain without
opening the skull (p. 64).

What Are Psychology’s Six Main Perspectives? 17
has led psychology in circles. The mind, he said, is something so
subjective that it cannot even be proved to exist (Skinner, 1990).
(Think about it: Can you prove you have a mind?) As Skinner
noted wryly, “The crucial age-old mistake is the belief that . . . what
we feel as we behave is the cause of our behaving” (Skinner, 1989,
p. 17). Thus, for the behaviorists, a person’s thoughts or emotions
became irrelevant—it was only behavior that could be reliably
observed and measured. So, for example, behaviorists examined
whether a young child would learn to avoid a harmless white rat
if the rat was paired with a sudden loud sound. Importantly, the
behaviorists refrained from making any subjective assumptions
about what the outward behavior (avoidance) represented inter-
nally (such as fear).
We can summarize the radical new idea that drove behavior-
ism this way: Psychology should be limited to the study of observ-
able behavior and the environmental stimuli that shape behavior.
This behavioral perspective called attention especially to the way
our actions are modified by their consequences, as when a child is
praised for saying “Thank you” or an adult is rewarded for good job
performance with a pay raise. The behaviorists contributed greatly
to our detailed understanding of environmental forces that impact
all kinds of human learning, and have also given us powerful strat-
egies for changing behavior by altering the environment (Alferink,
2005; Roediger, 2004). We will examine these ideas more closely in
Chapter 4.
How do you think behaviorists, with their emphasis on reward and punishment,
might explain procrastination? Consider the rewards reaped from putting off some-
thing you don’t want to do: Instead of the dreaded work, you likely spend the time
doing something you enjoy, which is instantly gratifying. Then, when you tackle the
problem at the last minute, you get rewarded by the feeling of success when you man-
age to pull it off and get it done just in the nick of time! Is it any wonder why pro-
crastination is a difficult behavior to change? Fortunately, in Chapter 4, you will learn
some effective strategies offered by these same behaviorists for overcoming this trou-
blesome pattern.
The Whole-Person Perspectives: Psychodynamic, Humanistic,
and Trait and Temperament Psychology
As the 20th century dawned, a new challenge to Wundt and structuralism came
from the Viennese physician Sigmund Freud and his disciples, who were developing
a method of treating mental disorders based on yet another radical idea: Personality
and mental disorders arise mainly from processes in the unconscious mind, outside of
our awareness (refer to Table 1.1). Although Freud was not the first to suggest that we
are unaware of some mental processes, neither structuralism nor functionalism had
imagined that unconscious processes could dominate the personality and cause mental
disorders. Moreover, Freud’s psychoanalytic theory aimed to explain the whole person,
not just certain components (such as attention, perception, memory, behavior, or emo-
tion), as other schools of psychology had done. His goal was to explain every aspect of
mind and behavior in a single, grand theory.
Psychodynamic Psychology Freud could be a difficult mentor, provoking many
of his followers to break ranks and develop their own theories. We use the term
psychodynamic to refer both to Freud’s ideas and to all these other neo-Freudian
formulations that arose from Freud’s notion that the mind (psyche), especially the
unconscious mind, is a reservoir of energy (dynamics) for the personality. This en-
ergy, says psychodynamic psychology, is what motivates us.
behavioral perspective A psychological view-
point that finds the source of our actions in environ-
mental stimuli, rather than in inner mental processes.
psychodynamic psychology A clinical
approach emphasizing the understanding of mental
disorders in terms of unconscious needs, desires,
memories, and conflicts.
S R
Strict behaviorists, such as B. F. Skinner, believe that psy-
chology should focus on the laws that govern behavior—that
is, on the relations between stimuli (S) and responses (R)—
rather than on the subjective processes of the mind.

18 C H A P T E R 1 Mind, Behavior, and Psychological Science
The first and best-known representative of the psychodynamic approach is, of
course, Sigmund Freud, whose system is called psychoanalysis. Originally conceived as
a medical technique for treating mental disorders, psychoanalysts emphasize the analy-
sis of dreams, slips of the tongue (the so-called Freudian slip), and a technique called
free association to gather clues to the unconscious conflicts and “unacceptable” desires
thought to be censored by consciousness. For example, psychoanalysts might interpret
a person’s pattern of self-defeating behavior—such as procrastination—as motivated
by an unconscious fear of failure.
Like Freud, most psychoanalysts today are physicians with a specialty in psychiatry
and advanced training in Freudian methods. (And now, as promised, you know the dif-
ference between a psychologist and a psychoanalyst.) But these practitioners are not the
only ones aspiring to explain the whole person. Two other groups share an interest in a
global understanding of the personality, humanistic psychology and trait and tempera-
ment psychology. Here, we group all three under the heading whole-person perspectives.
Humanistic Psychology Reacting to the psychoanalytic emphasis on sinister forces
in the unconscious, humanistic psychology took a different tack. Their radical new
idea was an emphasis on the positive side of our nature that included human ability,
growth, and potential (refer to Table 1.1). Led by the likes of Abraham Maslow and
Carl Rogers, they offered a model of human nature that proposed innate needs for
growth and goodness, and also emphasized the free will people can exercise to make
choices affecting their lives and growth (Kendler, 2005).
In the humanistic view, your self-concept and self-esteem have a huge influence
on your thoughts, emotions, and actions, all of which ultimately impact development
of your potential. Like psychodynamic psychology, humanistic psychology has had a
major impact on the practice of counseling and psychotherapy.
Trait and Temperament Psychology The ancient Greeks, who anticipated so
many modern ideas, proclaimed that personality is ruled by four body humors (flu-
ids): blood, phlegm, melancholer, and yellow bile. Depending on which humor was
dominant, an individual’s personality might be sanguine (dominated by blood),
slow and deliberate (phlegm), melancholy (melancholer), or angry and aggressive
(yellow bile).
We no longer buy into the ancient Greek typology, of course. But their notion of
personality traits lives on in modern times as trait and temperament psychology. The fun-
damental idea distinguishing this group says: Differences among people arise from
differences in persistent characteristics and internal dispositions called traits and
temperaments (refer to Table 1.1).
psychoanalysis An approach to psychology
based on Sigmund Freud’s assertions, which empha-
size unconscious processes. The term is used to refer
broadly both to Freud’s psychoanalytic theory and to his
psychoanalytic treatment method.
whole-person perspectives A group of
psychological perspectives that take a global view of
the person: Included are psychodynamic psychology,
humanistic psychology, and trait and temperament
psychology.
humanistic psychology A clinical approach
emphasizing human ability, growth, potential, and
free will.
C O N N E C T I O N CHAPTER 10
People’s personalities differ on five
major trait dimensions, cleverly
called the Big Five (p. 423).
trait and temperament psychology A
psychological perspective that views behavior and
personality as the products of enduring psychological
characteristics.
This cartoon illustrates the Freudian slip, which suggests that thoughts or feelings we try to hide
from others will sometimes accidentally find their way into our speech.

What Are Psychology’s Six Main Perspectives? 19
You have probably heard of such traits as introversion and extraversion, which
seem to be fundamental characteristics of human nature. Other traits psycholo-
gists have identified in people all over the world include a sense of anxiety or
well-being, openness to new experiences, agreeableness, and conscientiousness.
We will examine these “Big Five” personality traits (as well as the other whole-
person theories) more closely in Chapter 10. Some psychologists also propose that
we differ on an even more fundamental level called temperament, thought to ac-
count for the different dispositions observed among newborn babies (and among
adults as well).
Trait and temperament psychologists might explain procrastination in terms of
the extent to which a person possesses the trait of conscientiousness. So, for exam-
ple, a person who is high in conscientiousness—in other words, takes commitments
very seriously—would be less likely to procrastinate. The individual who habitually
puts things off, yet doesn’t get stressed at missed deadlines, would be labeled low on
conscientiousness and in possession of an easy temperament (thus explaining the low
stress). All these individual characteristics would be presumed to be at least partly
biological in nature and would be expected to be fairly consistent over time and
across situations.
The Developmental Perspective: Changes Arising
from Nature and Nurture
Change may be the only constant in our lives. According to the developmental perspec-
tive, psychological change results from the interaction between the heredity written
in our genes and the influence of our environment (see Table 1.1). But which counts
most heavily: nature (heredity) or nurture (environment)? As we have seen, biological
psychologists emphasize nature, while behaviorists emphasize nurture. Developmental
psychology is where the two forces meet.
The big idea that defines the developmental perspective is this: People change in
predictable ways as the influences of heredity and environment unfold over time. In
other words, humans think and act differently at different times of their lives. Physi-
cally, development can be seen in such predictable processes as growth, puberty,
and menopause. Psychologically, development includes the acquisition of language,
logical thinking, and the assumption of different roles at different times of life. De-
velopmental psychologists, then, might not be surprised by the teen who procrasti-
nates. On the contrary, they may see it as normal behavior at that age, given that
teens are still learning how to juggle multiple responsibilities and accurately esti-
mate how long things take to complete—all while simultaneously coping with their
changing bodies and social worlds.
In the past, much of the research in developmental psychology has focused on
children—in part because they change so rapidly and in rather predictable ways. De-
velopmental psychologists are increasing their scrutiny of teens and adults, however, as
we discover how developmental processes continue throughout our lives. In Chapter 7,
we will explore some common patterns of psychological change seen across the entire
lifespan, from conception to old age. The developmental theme will appear elsewhere
throughout this text, too, because development affects all our psychological processes,
from biology to social interaction.
The Sociocultural Perspective: The Individual in Context
Who could deny that people exert powerful influences on each other? The sociocultural
perspective places the idea of social influence center stage. From this viewpoint, social
psychologists probe the mysteries of liking, loving, prejudice, aggression, obedience,
and conformity. In addition, many have become interested in how these social pro-
cesses vary from one culture to another (refer to Table 1.1).
developmental perspective One of the six
main psychological viewpoints, distinguished by its
emphasis on nature and nurture and on predictable
changes that occur across the lifespan.
sociocultural perspective A main psychologi-
cal viewpoint emphasizing the importance of social
interaction, social learning, and culture in explaining
human behavior.

20 C H A P T E R 1 Mind, Behavior, and Psychological Science
Culture, a complex blend of human language, beliefs, customs, values, and traditions,
exerts profound influences on all of us. We can see culture in action not only as we com-
pare people of one continent to those of another but also by comparing people, for exam-
ple, in the California–Mexican culture of San Diego and the Scandinavian-based culture
of Minnesota. Psychology’s earlier blindness to culture was due, in part, to the beginnings
of scientific psychology in Europe and North America, where most psychologists lived
and worked under similar cultural conditions (Lonner & Malpass, 1994; Segall et al.,
1998). Today the perspective has broadened: Less than half of the world’s half-million
psychologists live and work in the United States, and interest in psychology is growing in
countries outside of Europe and North America (Pawlik & d’Ydewalle, 1996; Rosenz-
weig, 1992, 1999). Still, much of our psychological knowledge has a North American/Eu-
ropean flavor. Recognizing this bias, cross-cultural psychologists have begun the long task of
reexamining the “laws” of psychology across cultural and ethnic boundaries (Cole, 2006).
Proponents of the sociocultural view do not, of course, deny the effects of heredity
or learning or even of unconscious processes. Rather, they bring to psychology a pow-
erful additional concept: the power of the situation. From this viewpoint, then, the so-
cial and cultural situation in which the person is embedded can sometimes overpower
all other factors that influence behavior. For example, certain cultures place greater
emphasis on meeting deadlines, which would in turn influence the behavior (such as
procrastination) of an individual in that culture. What situational or cultural forces
have, in your own past, interfered with your timely attention to a project?
Together, then, these six perspectives all play key roles in developing a holistic
understanding of human behavior. As we have seen with our example of procrastina-
tion, many perspectives can reasonably applied to any single behavior—and rarely is
just one perspective sufficient to adequately explain the behavior. (We hasten to add,
however, that explanations for a behavior are not intended as justifications for it.
Instead, they function well as clues for overcoming a behavior when it is problematic,
or for understanding behaviors in others.)
To summarize the perspectives we have just covered, please have a look at Figure 1.4.
There you will find a thumbnail overview of the main viewpoints that make up the spec-
trum of modern psychology.
The Changing Face of Psychology
Modern psychology is a field in flux. In recent decades, the biological, cognitive, and
developmental perspectives have become dominant. And increasingly, adherents of once-
conflicting perspectives are making connections and joining forces: We now see such
new and strange hybrid psychologists as “cognitive behaviorists”
or “evolutionary developmentalists.” At the same time, nearly all
specialties within psychology seem eager to make a connection
with neuroscience, which is rapidly becoming one of the pillars
of the field.
We also call your attention to a noteworthy shift in the propor-
tion of psychologists who are women and members of minority
groups. Ethnic minorities—especially Asians, African Americans,
and Latinos—are becoming psychologists in increasing numbers
(Kohout, 2001). Even more striking is the new majority status
of women in psychology. In 1906, only 12 percent of Ameri-
can psychologists listed were women, according to a listing in
American Men of Science (named with no irony intended). By
1921, the proportion had risen above 20 percent. And now,
women receive more than two-thirds of the new doctorates
awarded in the field each year (Cynkar, 2007; Kohout, 2001).
Although psychology has always included a higher pro-
portion of women than any of the other sciences, women
have often found gender biases blocking their career paths
culture A complex blend of language, beliefs,
customs, values, and traditions developed by a
group of people and shared with others in the same
environment.
cross-cultural psychologists Those who
work in this specialty are interested in how psychologi-
cal processes may differ among people of different
cultures.
Dr. Phil Zimbardo, one of your authors,
is a social psychologist who studies the
“power of the situation” in controlling
our behavior. You will see how strongly
social situations affect our behavior when
you read about his Stanford Prison
Experiment in Chapter 11.
Cross-cultural psychologists, such as this researcher in Kenya,
furnish important data for checking the validity of psychological
knowledge.

What Are Psychology’s Six Main Perspectives? 21
FIGURE 1.4
Summary of Psychology’s Six Main Perspectives
The Biological Perspective
focuses on:
• nervous system
• endocrine system
• genetics
• physical characteristics
The Behavioral Perspective
focuses on:
• learning
• control of behavior by the
environment
• stimuli and responses—but
not mental processes
The Developmental Perspective
focuses on:
• changes in psychological
functioning across the life span
• heredity and environment
The Cognitive Perspective
focuses on:
• mental processes, such as
thought, learning, memory,
and perception
• the mind as a computer-like
”machine”
• how emotion and motivation
influence thought and
perception (”hot cognition”)
The Whole-Person Perspective
includes:
• the Psychodynamic View, which
emphasizes unconscious
motivation and mental disorder
• the Humanistic View, which
emphasizes mental health and
human potential
• the Trait and Temperament View,
which emphasizes personality
characteristics and individual
differences
The Sociocultural Perspective
focuses on:
• social influences on behavior and
mental processes
• how individuals function in
groups
• cultural differences
questions, or create one of your own. Can
you explain how at least four of psychol-
ogy’s perspectives might explain that be-
havior? If so, you are well on your way to
understanding the importance of multiple
perspectives in the field of psychology.
APPLYING PSYCHOLOGY’S PERSPECTIVES
The six perspectives in psychology can be
one of the most useful tools you take away
from this class. How? By applying them
to behaviors of interest in your own life,
you can become more sophisticated and
more accurate in your interpretations of
why people do what they do. Why do some
people commit acts of terror or violence?
What causes infidelity in romantic relation-
ships? What makes a person feel anxious
when speaking in public? Why do people
smoke cigarettes? Consider one of these

22 C H A P T E R 1 Mind, Behavior, and Psychological Science
(Furumoto & Scarborough, 1986). For example, G. Stanley Hall, one of the pioneers of
American psychology, notoriously asserted that academic work would ruin a woman’s
health and cause deterioration of her reproductive organs. Nevertheless, as early as
1905, the American Psychological Association elected its first female president, Mary
Whiton Calkins. See Table 1.2 for a sampling of other important contributions made
by women to the field of psychology.
PSYCHOLOGY MATTERS
Psychology as a Major
Becoming a fully fledged psychologist requires substantial training beyond the bach-
elor’s degree. In graduate school, the psychology student takes advanced classes in one
or more specialized areas while developing general skills as a scholar and researcher.
On completion of the program, the student receives a master’s or doctor’s degree,
typically a PhD (Doctor of Philosophy), a PsyD (Doctor of Psychology), or an EdD
(Doctor of Education).
Satisfying careers are available, however, at various levels of education in psychology,
although the widest range of choices is available to holders of a doctorate (Smith, 2002b).
In most states, a license to practice psychology requires a doctorate plus a supervised intern-
ship. Most college and university teaching or research jobs in psychology also require a
doctorate.
A master’s degree, typically requiring two years of study beyond the bache-
lor’s level, may qualify you for employment as a psychology instructor at the high
school level or as an applied psychologist in certain specialties, such as counseling.
Master’s-level psychologists are common in human service agencies, as well as in
private practice (although many states do not allow them to advertise themselves as
“psychologists”).
Holders of associate’s degrees and bachelor’s degrees in psychology or related
human services fields may find jobs as psychological aides and technicians in agencies,
TABLE 1.2 A Sampling of Women’s Contributions to Psychology
Research Area Institutional Affiliation
Mary Ainsworth Infant attachment University of Toronto
Mary Calkins Memory, psychology of the self Wellesley College
Christine Ladd Franklin Logic and color vision Johns Hopkins University
Carol Gilligan Gender studies, moral development Harvard University
Julia Gulliver Dreams and the subconscious self Rockford University
Diane Halpern Critical thinking, gender differences University of Cincinnati
Elizabeth Loftus False memory Stanford University
Eleanor Maccoby Developmental psychology, effects
of divorce on children
University of Michigan
Lillien Martin Psychophysics Wellesley College
Christina Maslach Burnout and job stress Stanford University
Anna McKeag Pain Bardwell School
Sandra Scarr Intelligence Harvard University
Margaret Washburn Perception Vassar College

How Do Psychologists Develop New Knowledge? 23
hospitals, nursing homes, and rehabilitation centers. A bachelor’s degree in psychology,
coupled with training in business or education, can also lead to interesting careers in
personnel management or education.
Further information about job prospects and salary levels for psychologists is
available online in the U.S. Department of Labor’s Occupational Outlook Handbook
(2011–2012 edition) at www.bls.gov/oco/home.htm. You might also check out the
American Psychological Association’s career pages at www.apa.org/careers/resources/
index.aspx.
Check Your Understanding
1. RECALL: René Descartes made a science of psychology possible
when he suggested that __________.
2. APPLICATION: “The differences between men and women are
mainly the result of different survival and reproduction issues faced
by the two sexes.” Which of the main viewpoints in psychology
would this statement represent?
3. APPLICATION: If you were a teacher trying to understand how
students learn, which of the following perspectives would be most
helpful?
a. the cognitive view
b. the psychodynamic view
c. structuralism
d. the trait and temperament view
4. RECALL: To which of the structuralists’ and functionalists’ ideas
did the behaviorists object?
5. RECALL: Which of the whole-person views focuses on
understanding the unconscious mind?
6. APPLICATION: “Soldiers may sometimes perform heroic
acts, not so much because they have heroic personality traits
but because they are in a situation that encourages heroic
behavior.” Which perspective is this observation most consistent
with?
7. APPLICATION: If you wanted to tell whether a friend had
experienced a perceptual shift while viewing the Necker cube, you
would have to use the method of __________, which was pioneered
by Wundt and the structuralists.
8. UNDERSTANDING THE CORE CONCEPT: Which of the
following sets of factors are all associated with the perspective
indicated?
a. memory, personality, environment: the behavioral perspective
b. mental health, mental disorder, mental imagery: the trait and
temperament perspective
c. heredity, environment, predictable changes throughout the
lifespan: the developmental perspective
d. neuroscience, evolutionary psychology, genetics: the cognitive
perspective
Answers 1. sensations and behaviors are the result of activity in the nervous system. 2. The biological perspective—in particular the viewpoint
of evolutionary psychology 3. a 4. They particularly objected to the concept of the mind as an object of scientific study. They also objected to
introspection as a subjective and therefore unscientific method. 5. The psychodynamic view, especially psychoanalysis 6. The sociocultural
perspective 7. introspection 8. c.
1.3 KEY QUESTION
How Do Psychologists Develop New Knowledge?
Earlier in this chapter, we saw how Descartes’ radical new idea separating the spiritual
mind from the physical body enabled scientists to start identifying biological bases for
behaviors, thus challenging the pseudoscientific “common sense” that attributed cer-
tain behaviors to mysterious spiritual forces. Today, psychology continues to dispute
the unfounded claims of pseudoscience, which range from palm reading to psychic
predictions to use of crystals to heal physical ailments.
What makes psychology different from these pseudopsychological approaches to
understanding people? Not one of them has survived trial by the scientific method,
which is a way of testing ideas against observations. Instead, pseudo-psychology is
based on hope, confirmation bias, anecdote—and human gullibility.
Study and Review at MyPsychLab

www.bls.gov/oco/home.htm

www.apa.org/careers/resources/index.aspx

24 C H A P T E R 1 Mind, Behavior, and Psychological Science
You might think this an arrogant view for psychologists to take. Why can’t we make
room for many different ways of understanding people? In fact, we do. Psychologists
welcome sociologists, anthropologists, psychiatrists, and other scientists as partners in
the enterprise of understanding people. We reject only those approaches that mislead
people by claiming to have “evidence” that is, in truth, only anecdotes and testimonials.
What makes psychology a real science, then, is the method. As our Core Concept
for this section says:
Core Concept 1.3
Psychologists, like all other scientists, use the scientific method to
test their ideas empirically.
What is this marvelous method? Simply put, the scientific method is a way of putting ideas
to an objective pass–fail test. The essential feature of this test is empirical investigation,
the collection of objective information by means of careful measurements based on di-
rect experience. From empirical investigations, psychological science ultimately seeks to
develop comprehensive explanations for behavior and mental processes. In science, we
call these explanations theories—a commonly misunderstood word.
“It’s only a theory,” people may say. But to a scientist, theory means something
special. In brief, a scientific theory is a testable explanation for a broad set of facts or
observations (Allen, 1995; Kukla, 1989). Obviously, this definition differs from the
way people customarily use the term. In everyday language, theory can mean wild
speculation or a mere hunch—an idea that has no evidence to support it. But to a sci-
entist, a good theory has two attractive attributes: (a) the power to explain the facts
and (b) the ability to be tested. Examples of well-supported theories include Einstein’s
theory of relativity, the germ theory of disease, and Darwin’s theory of natural selec-
tion. And as you will see throughout this text, psychology has many well-supported
theories too. But what are the essential steps involved in testing a theory?
Four Steps in the Scientific Method
Testing any idea scientifically requires four basic steps that we can illustrate by apply-
ing them to our problem examining the effects of sugar on children’s activity (see
Figure 1.5). All scientists follow essentially the same steps, no matter whether their
field is psychology, biology, chemistry, astronomy, or any other scientific pursuit. Thus,
it is the method that makes these fields scientific, not their subject matter.
Develop a Hypothesis The scientific method first requires a specific testable
idea or prediction, called a hypothesis. The term literally means “little theory”
because it often represents only one piece of a larger theoretical explanation. For
example, a hypothesis predicting that introverted people are attracted to extra-
verted people might be part of a theory tying together all the components of
romantic attraction. Alternatively, a hypothesis can just be an interesting idea that
piques our curiosity—as in our study of the effects of sugar on children.
To be testable, a hypothesis must be potentially falsifiable—that is, stated in such a
way that it can be shown to be either correct or incorrect. Let’s illustrate how this works
with the following hypothesis: Sugar causes children to become hyperactive. We could test
it by having children consume sugar and then observing their activity level. If we find no
increase, the hypothesis is falsified. The hypothesis would not be falsifiable if we merely
stated a value judgment—for example, that sugar is “bad” for children. Science does not
aim to make value judgments and cannot answer questions that can’t be tested empiri-
cally. See Table 1.3 for examples of other questions science cannot answer.
Next, the scientist must consider precisely how the hypothesis will be tested. This
means defining all aspects of the study in concrete terms called operational definitions.
The following examples could serve as operational definitions for our study.
scientific method A four-step process for em-
pirical investigation of a hypothesis under conditions
designed to control biases and subjective judgments.
empirical investigation An approach to
research that relies on sensory experience and observa-
tion as research data.
theory A testable explanation for a set of facts or
observations. In science, a theory is not just specula-
tion or a guess.
hypothesis A statement predicting the outcome of
a scientific study; a statement predicting the relation-
ship among variables in a study.
operational definitions Objective descriptions
of concepts involved in a scientific study. Operational
definitions may restate concepts to be studied in be-
havioral terms (e.g., fear may be operationally defined
as moving away from a stimulus). Operational defini-
tions also specify the procedures used to produce and
measure important variables under investigation (e.g.,
“attraction” may be measured by the amount of time
one person spends looking at another).

How Do Psychologists Develop New Knowledge? 25
• Operational definition of “children.” We can’t test all the children in the world, of
course. So, our operational definition of “children” might be all the third graders
in one class at a nearby elementary school.
• Operational definition of “sugar.” Likewise, we could define what we mean by
“sugar” as the amount of sugar in a commercial soft drink. If we decide, for example,
to use 7Up as our sugar source, we could operationally define “sugar” as the 38
grams available in one can of 7Up. (Using a noncaffeinated beverage, such as 7Up,
avoids the possibly confounding effects of caffeine on the children’s behavior.)
FIGURE 1.5
Four Steps in the Scientific Method
1. Developing a hypothesis
2. Gathering objective data
3. Analyzing the results
N
u
m
b
er
o
f
ch
ild
re
n
Activity level
Low High
4. Publishing, criticizing, and
replicating the results
TABLE 1.3 What Questions Can the Scientific Method Not Answer?
The scientific method is not appropriate for answering questions that cannot be put to an objective,
empirical test. Here are some examples of such issues:
Topic Question
Ethics Should scientists do research with animals?
Values Which culture has the best attitude toward work
and leisure?
Morality Is abortion morally right or wrong?
Preferences Is rap music better than blues?
Aesthetics Was Picasso more creative than Van Gogh?
Existential issues What is the meaning of life?
Religion Does God exist?
Law What should be the speed limit on interstate
highways?
Although science can help us understand such issues, the answers ultimately must be settled by logic, faith,
legislation, consensus, or other means that lie beyond the scope of the scientific method.

26 C H A P T E R 1 Mind, Behavior, and Psychological Science
• Operational definition of hyperactive. This will be a bit more complicated. Sup-
pose we have specially trained observers who will rate each child’s behavior on the
following 5-point scale:
passive moderately active very active
1 2 3 4 5
So, if our study specifies giving some children a sugar-sweetened drink and others the
same drink containing artificial sweetener, we can operationally define “hyperactive”
as a significantly higher average activity rating for the group getting the sugared drink.
With our hypothesis and operational definitions in hand, we have taken the first step in
our scientific study. Next, we test our hypothesis. (The great failing of pseudosciences like
astrology or fortunetelling is they never actually take this step of testing their assertions.)
Collect Objective Data This is where we begin our empirical investigation. Literally,
empirical means “experience based”—as contrasted with speculation based solely on
hope, authority, faith, or “common sense.” This literal definition can be misleading,
however, if we mistakenly classify one person’s experience as “empirical.” Regardless
of how powerful one person’s experience might be, it remains merely a testimonial
or an anecdote that needs to be verified under the controlled conditions of scientific
research. As we discussed in the Critical Thinking section earlier in this chapter, it
would be risky to assume one person’s experiences would be true for others.
Investigating a question empirically means collecting evidence carefully and sys-
tematically, using one of several tried-and-true methods we will examine in depth in
the next section. Such methods are designed to avoid false conclusions caused by our
expectations, biases, and prejudices. Having done so, the data we obtain can be applied,
or generalized, to a larger group of people with more confidence.
Analyze the Results and Accept or Reject the Hypothesis Once we have collected
our data, we then analyze it using some type of mathematical or statistical formula. If you
hate math, though, fear not: Detailed explanations of statistical procedures are beyond
the scope of this book—in fact, advanced psychology students take entire courses on
statistical methods! In our experiment, however, the statistical analysis will be relatively
straightforward, because we merely want to know whether scores for the children receiv-
ing sugar are higher than those taking the sugar-free drink. If so, we can declare that our
hypothesis has been supported. If not, we will reject it. Either way, we have learned some-
thing. You can find a statistical appendix for this text online at www.mypsychlab.com.
Publish, Criticize, and Replicate the Results The final step in the scientific
method exposes a completed study to the scrutiny and criticism of the scientific com-
munity by publishing it in a professional journal, making a presentation at a profes-
sional meeting, or—occasionally—writing a book. Then the researchers wait for the
critics to respond.
If colleagues find the study interesting and important—and especially if it challenges
other research or a widely held theory—critics may look for flaws in the research de-
sign: Did the experimenters choose the participants properly? Were the statistical anal-
yses done correctly? Could other factors account for the results? Alternatively, they
may decide to check the study by replicating it. To replicate the experiment, they would
redo it themselves to see if they get the same results.
In fact, our study of the effects of sugar on children is a simplified replication of
research done previously by Mark Wolraich and his colleagues (1995). Their study lasted
three weeks and compared one group of children who ate a high-sugar diet with another
group given a low-sugar diet with artificial sweeteners. Contrary to folk wisdom, the
researchers found no differences between the groups in behavior or cognitive (mental)
function. So, if our study were to find a “sugar high” effect, it would contradict the
Wolraich findings, and you can be sure it would receive careful scrutiny and criticism.
Criticism also occurs behind the scientific scenes to filter out poorly conceived or
executed research prior to publication. Journal editors and book publishers (including
data Pieces of information, especially informa-
tion gathered by a researcher to be used in testing a
hypothesis. (Singular: datum.)
replicate In research, this refers to doing a study
over to see whether the same results are obtained. As
a control for bias, replication is often done by someone
other than the researcher who performed the original
study.

www.mypsychlab.com

How Do Psychologists Develop New Knowledge? 27
the publishers of this book) routinely seek opinions of expert reviewers. As a result,
authors usually receive helpful, if sometimes painful, suggestions for revision. Only
when a hypothesis has cleared all these hurdles will editors put it in print and scholars
tentatively accept it as scientific “truth.”
We should emphasize, however, that scientific findings are always tentative. As long
as they stand, they stand in jeopardy from a new study that requires a new interpreta-
tion or sends earlier work to the academic scrap heap. Consequently, the results of the
Wolraich sugar study could be eventually replaced by better, more definitive knowl-
edge. Obviously, then, the scientific method is an imperfect system, but it is the best
method ever developed for testing ideas about the natural world. As such, it represents
one of humankind’s greatest intellectual achievements.
Five Types of Psychological Research
The scientific method, then, provides much greater credibility for ideas than does mere
anecdote or pseudoscience. Within this method, there are several specific ways a re-
searcher can collect objective data. Each has unique advantages, as well as limitations.
One key step in conducting good research, then, is choosing the method best suited to
your particular hypothesis and resources.
Experiments Like the word theory, the term experiment also has a very specific mean-
ing in science. Contrary to everyday usage of the term to refer to any type of formal
or informal test, the scientific use of the word applies to a particular set of procedures
for collecting information under highly controlled conditions. As a result of its careful
design, an experiment is the only type of research method we will discuss here that can
reliably determine a cause–effect relationship. Thus, if a hypothesis is worded in a man-
ner that suggests cause and effect—as ours does in stating that sugar causes hyperactivity
in children—then the experiment is the best option. Let’s see how our sugar study can
determine cause and effect.
In the most basic experimental design, the researcher varies only one factor, known
as a variable, and keeps all other conditions of the experiment under constant control—
the same for all participants. Scientists call that one variable the independent variable
because it operates independently of everything else in the study. In our sugar study,
we hypothesized that sugar causes hyperactivity, so sugar/no sugar is our independent
variable. By giving some children sugar and others a sugar substitute, and keeping all
other conditions constant, we are manipulating the independent variable. Because
all other aspects of the experiment are held constant, we can say that the indepen-
dent variable is the cause of any experimental effects we observe.
Likewise, the dependent variable is the outcome variable, or what we hypothesize
to be the effect. In other words, any experimental effects we observe depend on the
independent variable that we have introduced. In our sugar experiment, then, the de-
pendent variable is the children’s activity level. If the group receiving the sugar is later
observed to be more active, we can be sure it was the sugar that caused the hyperactiv-
ity, because it was the only difference between the two groups.
Before going any further, we should clarify two other important terms used to identify
our participants. Those receiving the treatment of interest (in our study, the high-sugar
drink) are said to be in the experimental condition. Individuals exposed to the experi-
mental condition, then, make up the experimental group. Meanwhile, those in the control
group enter the control condition, where they do not receive the special treatment. (In our
study, the control group will get the artificially sweetened drink.) Thus, the control group
serves as a standard against which to compare those in the experimental group.
How do we decide which participants will be placed into each group? The easy way to
divide them up would be to let the children (or their parents) decide, based on their own
preferences. The problem with that, however, is there could be some difference between
children whose parents let them drink sugared drinks and those whose parents do not.
Perhaps, for example, parents who allow their children to drink sugared drinks are more
relaxed about rules in general, which could result in those same kids being rowdier in
their play—which would confound our results. Similarly, it wouldn’t do to put all the girls
experiment A kind of research in which the
researcher controls all the conditions and directly
manipulates the conditions, including the independent
variable.
independent variable A stimulus condition so
named because the experimenter changes it indepen-
dently of all the other carefully controlled experimental
conditions.
dependent variable The measured outcome of a
study; the responses of the subjects in a study.
experimental group Participants in an experi-
ment who are exposed to the treatment of interest.
control group Participants who are used as a
comparison for the experimental group. The control
group is not given the special treatment of interest.
Distinguishing Independent and
Dependent Variables at
Simulate the Experiment
MyPsychLab

28 C H A P T E R 1 Mind, Behavior, and Psychological Science
in one group and all the boys in the other. Why not? There could be gender differences
in their physical reactions to sugar. In addition, one sex might be better than the other at
controlling their reactions. These pre-existing differences could impact our outcome.
The best solution is to use random assignment, by which participants are assigned to
each group purely by chance. One way to do this would be to list the children alpha-
betically and then assign alternating names to the experimental and control groups. In
this way, random assignment minimizes any pre-existing differences between the two
groups. This, in turn, assures that any differences in activity level are truly due to sugar
rather than to some other factor such as sex or parenting style.
In summary, the experimental method is the gold standard for finding cause-and-
effect relationships. It does so by isolating the variable of interest (the independent
variable) and holding all other conditions of the experiment constant. Random assign-
ment to experimental and control groups is used to minimize pre-existing differences
between the groups so we can be more confident that differences in the outcome (the
dependent variable) are due to the effects of the independent variable and nothing else.
Given the power of the experiment to find cause and effect, why do we need other
methods? For one reason, not all hypotheses aim to find cause and effect—some merely
wish to describe certain populations, such as determining what personality traits are
common among psychology students. For another, ethical considerations prevent us from
conducting certain kinds of experimental studies, notably those which might potentially
harm participants. In such instances, then, one of the following research methods is a
better or more practical choice.
Correlational Studies In addition to the considerations described above, there is yet
another factor that influences a researcher’s choice of method: Due to practical or ethi-
cal considerations, sometimes scientists cannot gain enough control over the situation
to allow them to conduct a true experiment. Suppose, for example, you wanted to test
the hypothesis that children who ingest lead-based paint run an increased risk of learn-
ing disabilities. (Lead-based paint is common in older homes, especially in low-income
urban housing.) You couldn’t do an experiment, because an experiment would require
you to manipulate the independent variable—which in this case would mean giving toxic
material (lead) to a group of children. Obviously, this would be harmful and unethical.
Fortunately, you can find a way around the problem—but at the expense of some
control over the research conditions. The solution takes the form of a correlational
study. In correlational research you, in effect, look for a “natural experiment” that has
already occurred by chance in the real world. So, in a correlational study on the ef-
fects of ingesting lead-based paint, you might look for a group of children who had
already been exposed to lead paint. Then you would compare them to another group
who had not been exposed. As a further control, you should try to match the groups
so they are comparable in every conceivable respect (such as age, family income, and
gender)—except in their exposure to lead-based paint.
The big drawback of a correlational study is that you can never be sure the groups
are completely comparable, because you did not randomly assign people to experimen-
tal groups or manipulate the independent variable. In fact, the groups may differ on
some important variables (such as access to health care or nutrition) that you could
have overlooked. Thus, even if you observe more learning disabilities among children
who were exposed to lead-based paint, you cannot conclude with certainty that expo-
sure to the paint caused the disabilities. The most you can say is that lead-based paint
is correlated (associated) with learning disabilities. This is, however, still useful, as it
narrows the search for links to learning disabilities. In addition, a series of solid corre-
lational findings sometimes pave the road to an experimental study, as we will discuss
in the following text. Many research findings reported in the media are likely to be
from correlational studies, rather than experimental ones, so let’s take a closer look at
what these findings mean and how we can accurately interpret them.
Three Types of Correlations If two variables show a pattern in which they vary in
the same direction (as one variable increases, so does the other), we say they have a
positive correlation. For example, we predicted a positive correlation in our hypothesis
random assignment A process used to assign
individuals to various experimental conditions
by chance alone.
correlational study A form of research in which
the relationship between variables is studied, but with-
out the experimental manipulation of an independent
variable. Correlational studies cannot determine cause-
and-effect relationships.
positive correlation A correlation indicating
that the variables change simultaneously in the same
direction: As one grows larger or smaller, the other
grows or shrinks in a parallel way.

How Do Psychologists Develop New Knowledge? 29
that children exposed to lead-based paint are at higher risk for learning disabili-
ties. But when one variable decreases as the other increases, this is called a negative
correlation. You would probably find a negative correlation between the amount of al-
cohol consumed by college students and their grade-point averages (as college students
increase their consumption of alcohol, their grade-point averages decrease). Finally, if
the variables have no relationship at all, there is a zero correlation, which is what you
might expect between height and GPA, for example (see Figure 1.6).
Researchers usually express the degree of correlation as a number that can range
from as low as –1.0 (reflecting a strong negative correlation) to a positive number as
high as +1.0 (indicating a strong positive correlation). It is important to note that a
correlation can show a strong relationship even when it is negative. (Note: Professors
often ask test questions about this!) Suppose we find a correlation of –0.7 between
anxiety and time spent studying. In other words, this is a negative correlation indicat-
ing more anxiety is correlated with less studying. Even though this is a negative cor-
relation, it shows a stronger relationship than the positive correlation of +0.4 that is
found, for example, between SAT scores and grades.
Interpreting Correlational Findings One of the most common errors in critical thinking
occurs when correlational findings are misinterpreted as cause-and-effect findings. For
example, some years ago, research identified a positive correlation between children’s
self-esteem and their performance in school. Did that mean high self-esteem caused kids
to do better in school? Not necessarily—and to conclude otherwise is a critical thinking
error! While that notion certainly fits our “common sense” ideas about the benefits of
self-esteem, without conducting an experiment, manipulating the independent variable
(self-esteem), and randomly assigning students to experimental and control conditions,
we cannot be sure what the causal factor is. Scientists often put the general principle
this way: Correlation does not necessarily mean causation.
In fact, any time you see a correlational finding, you must consider three possible
interpretations for the finding:
• A causes B. If “A” refers to the first variable mentioned—in this case, self-esteem—
and “B” refers to the second variable (grades), this interpretation recognizes that
self-esteem may indeed influence a student’s grades in school. That is, however,
only one possibility.
• B causes A. It could also be the case that grades in school influence self-esteem—in
other words, that our initial assumption about causality was backwards. If you
think about it, couldn’t it also be possible that students who do well in school feel
negative correlation A correlation indicating
that the variables change simultaneously in opposite
directions: As one becomes larger, the other gets
smaller.
zero correlation When two variables have no
relationship to each other.
FIGURE 1.6
Three Types of Correlation
The graphs illustrate the three main types of correlation, with data points for 27 individuals. (A) shows a positive correlation between SAT scores
and GPA; (B) shows a negative correlation between alcohol consumption and GPA; and (C) shows no correlation between height and GPA.
G
PA
Number of Drinks per Week
G
PA
SAT Scores
G
PA
Height
(B) Negative Correlation(A) Positive Correlation (C) No Correlation
200 400 600 800 2 4 6 7 9 10 12 4’6” 5”0” 5”6” 6’0” 6’6”
4.0
3.0
2.0
1.0
0.0
4.0
3.0
2.0
1.0
0.0
4.0
3.0
2.0
1.0
0.0
Explore the Concept Correlations
Do Not Show Causation at
MyPsychLab

30 C H A P T E R 1 Mind, Behavior, and Psychological Science
better about themselves as a result? If that were true, grades in school (rather than
self-esteem) would be the driving force of the correlation.
• C causes both A and B. Yet a third possibility must also be recognized in contem-
plating correlational findings: What if a different variable (C)—something not
measured in the study—was actually the driving force behind the observed rela-
tionship? In this example, what might influence a student’s school performance
and his or her self-esteem? Perhaps more time spent with parents helps a child
succeed in school and also improves the child’s self-esteem. In that case, we would
be mistaken to assume that grades and self-esteem were related causally—instead,
they just appeared that way due to lack of attention to the true source of both.
The important thing to remember is that without a true experiment, speculation about
cause is just that: speculation—and potentially dangerous speculation at that. This dan-
ger was powerfully illustrated by the very findings we have discussed here: In the wake of
correlational studies showing a relationship between self-esteem and grades, millions of
dollars were spent nationwide on programs training teachers to help improve students’
self-esteem, with the mistaken assumption that higher self-esteem would in turn raise
students’ grades. Did it work? No. On the contrary, follow-up experimental research
discovered that getting good grades is one causal component in high self-esteem, provid-
ing support for the B causes A explanation given previously. Moreover, it turns out that
self-control (in this case, an example of a C variable) promotes both self-esteem and
school performance (Baumeister, 2003). Even trained researchers and lawmakers can
make mistakes when “common sense” biases their accurate interpretations of research.
Surveys Which type of learning do students prefer: listening to lectures, reading material
on their own, or participating in hands-on activities? If you want to know the answer to
this question, you don’t need to perform an experiment or a correlational study. Instead,
you can simply ask students what they like using a survey, which is a popular and effec-
tive method of determining people’s attitudes, preferences, or other characteristics.
Widely used by political pollsters and marketing consultants (as well as by many
researchers in psychology and sociology), surveys typically ask people for their re-
sponses to a prepared set of questions. The biggest advantage of the survey method
is its ability to gather data from large numbers of respondents relatively quickly and
inexpensively, such as through Internet surveys. This easy access to many people is also
the source of the survey’s biggest disadvantage: its vulnerability to a variety of biases.
What are some common biases in conducting or interpreting results of a survey?
Social desirability bias refers to respondents’ tendency to answer questions in ways
that are socially or politically correct (Schwarz, 1999). Other biases can stem from
wording of the questions (Are they clear? Do they use emotionally charged words to
elicit a particular type of response?), the sample (How well do the respondents repre-
sent the general population?), and the survey conditions (Is the survey anonymous?
Are people completing it in a setting that might bias their responses?)
If care is taken to avoid these biases, surveys can be very useful—but only when the
hypothesis can be legitimately studied with a survey. Examining the effects of sugar on
children’s activity level by asking parents if they’ve noticed their children behaving more
actively after consuming sugar, for example, would reveal parents’ opinions about sugar
and hyperactivity—but opinions do not empirically test the relationship in which we are
interested. Thus, it would not be an appropriate choice for solving our chapter problem.
Naturalistic Observations In her classic studies showing that chimpanzees have a
complex, tool-making culture, Jane Goodall observed chimps in their natural jungle
environment. Likewise, when psychological researchers want to know how people act
in their natural surroundings (as contrasted with the artificial conditions of a labora-
tory), they use the same method of naturalistic observation. This approach is a good
choice for studying child-rearing practices, shopping habits, or how people flirt in pub-
lic. Thus, the setting for a naturalistic observation could be as varied as a home, a
shopping mall, a restaurant, or a remote wilderness.
survey A technique used in descriptive research,
typically involving seeking people’s responses to a
prepared set of verbal or written items.
naturalistic observation A form of descriptive
research involving behavioral assessment of people or
animals in their natural surroundings.

How Do Psychologists Develop New Knowledge? 31
As you might guess, naturalistic observations are made under far
less controlled conditions than are experiments because the researcher
merely observes and records behaviors, rather than manipulating the en-
vironment. The best naturalistic observations, however, follow a care-
fully thought-out plan. Thus, such concerns as expectancy bias can be
minimized by use of systematic procedures for observation and data
collection and by careful training of observers.
The advantage of naturalistic observation is that you see the behav-
iors as they naturally occur, which often reveals insights not found in a
laboratory setting. In some situations, it is also more cost effective to
use the natural environment rather than try to reconstruct one in the
lab. The disadvantages include the lack of control over the environment,
which prohibits causal conclusions, as well as the time-consuming and
expensive nature of a well-designed naturalistic study.
Case Studies How might you study what shaped comedian Stephen Colbert’s sense
of humor? You can’t conduct any type of empirical research, because (for better or
worse) you have only one Stephen Colbert. In situations such as this, researchers must
rely on the case study, a unique type of research method that focuses in depth on only
one or a few individuals, usually with rare problems or unusual talents. For example,
in his book, Creating Minds, Howard Gardner (1993) used the case study method to
explore the thought processes of several highly creative individuals, including Einstein,
Picasso, and Freud. Therapists who use case studies to develop theories about mental
disorder sometimes call this the clinical method. By either name, the disadvantages of
this approach lie in its subjectivity, its small sample size, and the lack of control over
variables that could affect the individuals under study. These limitations severely restrict
the researcher’s ability to draw conclusions that can be generalized or applied with con-
fidence to other individuals. Nevertheless, the case study can sometimes give us valuable
information that could be obtained in no other way.
Controlling Biases in Psychological Research
Assisted suicide. Abortion. Capital punishment. Do you have strong feelings and opin-
ions on any of these issues? Emotion-laden topics can bring out biases that make criti-
cal thinking difficult, as we have seen. The possibility of bias, then, poses problems for
psychologists interested in studying such issues as child abuse, gender differences, or the
effects of racial prejudice—topics that may interest them precisely because of their own
strong opinions. Left uncontrolled, researcher biases can affect the ways they design a
study, collect the data, and interpret the results. Let’s take a look at two forms of bias
that require special vigilance in research.
Emotional bias, which we discussed earlier in connection with critical thinking,
involves an individual’s cherished beliefs, strong preferences, unquestioned assump-
tions, or personal prejudices. Often these are not obvious to the individual who has
such biases. For example, in his book Even the Rat Was White, psychologist Robert
Guthrie (1998) points out the bias in the long psychological tradition of research on
college students—who were most often White—without realizing they were introduc-
ing bias with their sample-selection procedures. This practice limited the applicabil-
ity of the research results to people of color. Fortunately, the scientific method, with
its openness to peer criticism and replication, provides a powerful counterbalance to
an experimenter’s emotional bias. Still, scientists would prefer to identify and control
their biases before potentially erroneous conclusions hit print.
Expectancy bias can also affect scientists’ conclusions when they observe only what
they expect to observe. (You can see a close kinship here with confirmation bias, also
discussed earlier.) Expectancy bias revealed itself in, for example, a notable study in
which psychology students trained rats to perform behaviors such as pressing a lever to
obtain food (Rosenthal & Lawson, 1964). The experimenters told some students their
rats were especially bright; other students heard their rats were slow learners. (In fact,
case study Research involving a single individual
(or, at most, a few individuals).
expectancy bias The researcher allowing his or
her expectations to affect the outcome of a study.
Jane Goodall used the method of naturalistic observation
to study chimpanzee behavior.
In his book Even the Rat Was White,
Robert Guthrie called attention to the
neglect of contributions by African
Americans in psychology.

32 C H A P T E R 1 Mind, Behavior, and Psychological Science
the experimenters had randomly selected both groups of rats from the same litters.)
Sure enough, the students’ data showed that rats believed to be bright outperformed
their supposedly duller littermates—in accord with the students’ expectations. How
could this be? Apparently, rats perform better for an enthusiastic audience! Follow-up
questionnaires showed that students with the “bright” rats were “more enthusiastic,
encouraging, pleasant, and interested in their rat’s performance.”
Not only can these sources of bias lead to erroneous conclusions, they can also pro-
duce expensive or even dangerous consequences. Imagine that you are a psychologist
working for a pharmaceutical company that wants you to test a new drug. With mil-
lions of dollars riding on the outcome, you may not be thinking with complete objectivity—
despite your most sincere efforts. And what about the doctors who will prescribe the
drug to patients in your study? Surely they will have high hopes for the drug, as will their
patients. And so the stage is set for expectancy bias to creep covertly into the study.
Fortunately, scientists have developed a strategy for controlling expectancy bias
by keeping participants in the research experimentally “blind,” or uninformed, about
whether they are getting the real treatment or a placebo (a sham “drug” or fake treat-
ment with no medical value). Even better is the double-blind study, which keeps both
participants and experimenters unaware of which group is receiving which treatment.
In a double-blind drug study, then, neither researchers nor participants would know
(until the end of the study) who was getting the new drug and who was getting the
placebo. This scientific trick controls for experimenters’ expectations by assuring that
experimenters will not inadvertently treat the experimental group differently from the
control group. And it controls for expectations of those receiving the experimental
treatment, because they are also “blind” to which group they have been assigned.
As you can imagine, expectancy bias could affect the response of the children in
our sugar study. Similarly, expectations of the observers could color their judgments.
To prevent this, we should ensure that neither the children nor the observers nor the
teachers know which children received each condition.
Ethical Issues in Psychological Research
Research also can involve serious ethical issues, such as the possibility of people being
hurt or unduly distressed. No researcher would want this to happen, yet the issues are
not always clear. Is it ethical, for example, in an experiment on aggression, to deliberately
provoke people by insulting them? What degree of stress is too high a price to pay for the
knowledge gained from the experiment? Such ethical issues raise difficult but important
questions, and not all psychologists would answer them in exactly the same way.
To provide some guidelines for researchers, the American Psychological Associa-
tion (APA) publishes Ethical Principles of Psychologists and Code of Conduct (2002a).
This document not only deals with the ethical obligation to shield research participants
from potentially harmful procedures, but it also warns researchers that information
acquired about people during a study must be held confidential (Knapp & VandeCreek,
2003; Smith, 2003a, b).
Informed Consent One important ethical guideline involves gaining informed consent,
which ensures that our participants are willingly engaging in our research. In our sugar
study, for example, we might explain to parents and the teacher the broad outline of
the experiment like this:
We propose to examine the supposed effect of sugar on children’s activity level.
To do so, we have planned a simple study of the children in your child’s third-
grade classroom—subject to the permission of their parents. The procedure
calls for dividing the children into two groups: At lunchtime, one group will
be given a commercial soft drink (7Up) sweetened with sugar, while the other
group will be given the same drink sweetened with artificial sweetener (Diet
7Up). The children will not be told to which groups they have been assigned.
For the rest of the school day, specially trained observers will rate the children’s
activity level. Once averaged, ratings will show whether the group receiving
C O N N E C T I O N CHAPTER 3
For many people, the brain
responds to placebos in much the
same way that it responds to
pain-relieving drugs (p. 110).
placebo (pla-SEE-bo) Substance that appears to
be a drug but is not. Placebos are often referred to as
“sugar pills” because they might contain only sugar,
rather than a real drug.
double-blind study An experimental procedure
in which both researchers and participants are unin-
formed about the nature of the independent variable
being administered.
informed consent Insures that research partici-
pants are informed of the procedures of the research,
as well as any potential dangers involved, so they may
opt out if desired.

How Do Psychologists Develop New Knowledge? 33
the sugar-sweetened drink was more active than the other group. We will
share the results with you at the end of the study.
Deception The use of deception poses an especially knotty problem for re-
searchers in psychology. As discussed above, the Ethical Principles document
states that, under most circumstances, participation in research should be volun-
tary and informed, so volunteers are told what challenges they will face and have
a real opportunity to opt out of the study. But the issue can be more complicated
than it first appears. What if you are interested in the “good Samaritan” prob-
lem: the conditions under which people will help a stranger in distress? If you tell
people you have contrived a phony emergency situation and ask them whether
they are willing to help, you will spoil the very effect you are trying to study.
Consequently, the guidelines do allow for deception under some conditions, pro-
vided no substantial risks are likely to accrue to the participants.
You might well ask, “Who judges the risks?” Most places where research is
done now have watchdog committees, called institutional review boards (IRBs),
that examine all studies proposed to be carried out within an institution, such as
a college, university, or clinic. Further, when a researcher uses deception, the APA
guidelines require that participants be informed of the deception as soon as pos-
sible without compromising the study’s research goals. Thus, participants are de-
briefed after the study to make sure they suffer no lasting ill effects. Despite these
precautions, some psychologists stand opposed to the use of deception in any form
of psychological research (Baumrind, 1985; Ortmann & Hertwig, 1997).
Animal Studies Another long-standing ethical issue surrounds the use of lab-
oratory animals, such as rats, pigeons, and monkeys. Animals make attractive
research subjects because of the relative simplicity of their nervous systems and the ease
with which large numbers of individuals can be maintained under controlled conditions.
Animals also have served as alternatives to humans when a procedure was deemed risky
or outright harmful, such as implanting electrodes in the brain to study its parts.
With such concerns in mind nearly 100 years ago, officers of the American Psycho-
logical Association established a Committee on Precautions in Animal Experimentation,
which wrote guidelines for animal research (Dewsbury, 1990). More recently, the APA’s
Ethical Principles document reiterated the experimenter’s obligation to provide decent liv-
ing conditions for research animals and to weigh any discomfort caused them against the
value of the information sought in the research. Additional safeguards appear in a 1985
federal law that regulates animal research (Novak & Suomi, 1988).
Recent years have seen a renewal of concern about the use of animals as research sub-
jects. When the research involves painful or damaging procedures, such as brain surgery,
electrode implants, or pain studies, people become especially uneasy. Some feel that limita-
tions should be more stringent, especially on studies using chimpanzees or other human-
like animals. Others believe that limitations or outright bans should apply to all animal
research, including studies of simple animals such as sea slugs (often used in neurological
studies). While many psychologists support animal research under the APA guidelines, the
issue remains a contested one (Bird, 2005; Plous, 1996).
PSYCHOLOGY MATTERS
The Perils of Pseudo-Psychology
Now that we understand the importance of the scientific method in determining the
credibility of claims we hear in the news, let’s look at a few serious problems that have
resulted from failures to follow this reliable system carefully.
In 1949, the Nobel Prize in medicine went to the inventor of the “lobotomy,” which
at the time was a crude brain operation that disconnected the frontal lobes from the
rest of the brain. Originally intended as a treatment for severe mental disorders, the
operation led instead to thousands of permanently brain-injured patients. The procedure
had no careful scientific basis, yet it became popular because people who wanted it to

34 C H A P T E R 1 Mind, Behavior, and Psychological Science
work didn’t ask critical questions. Emotional bias (in this case, the desire to cure people
with severe mental illnesses) promoted blind faith instead of clear-eyed scrutiny. As a
result, people failed to examine the evidence objectively.
For a modern example of pseudo-psychology’s harmful effects, we offer the widespread
belief that positive thoughts can cure dire diseases such as cancer. What could possibly be
wrong with that idea? For one thing, the evidence doesn’t support the notion that a per-
son’s state of mind significantly impacts the chances of recovery from a serious physical
illness (Cassileth et al., 1985; Coyne et al., 2007). For another, the attitude-can-make-you-
well belief can lead to “blaming the victim,” or assuming a patient didn’t get well because
his or her attitude was not sufficiently optimistic (Angell, 1985). And finally, for patients
suffering from severe illness, the lure of positive thinking certainly presents a less pain-
ful and traumatic solution than does surgery, chemotherapy, or other medical procedures.
Thus, their fear of the pain and suffering of proven medical treatment may bias them to put
their faith in positive thinking instead of the more scientifically valid course of treatment.
Throughout this text, we aim to help you improve your own scientific thinking by iden-
tifying and countering your own critical thinking errors. We will emphasize critical thinking
in three ways. One involves the problem presented at the beginning of each chapter: By ap-
plying the new knowledge you develop as you work your way through the chapter, you can
solve the problem. The second is through the way we have integrated our six critical think-
ing guidelines, introduced in the first section of this chapter, into discussions of controversial
issues in each chapter. In so doing, we hope you will become more accustomed to routinely
using these guidelines to think through other controversial issues you encounter in your life.
And, third, we have highlighted a special section at the end of each chapter, entitled “Critical
Thinking Applied.” In these features, we model the critical thinking process as we consider
a current issue related to the chapter topic—for instance, in this chapter we explore a popu-
lar treatment for autism. After reading each of these special sections, we challenge you to
follow our lead in critically thinking about some issue of particular interest to you in that
area. You can maximize your gain from this class by choosing topics especially relevant to
yourself, whether it be improving your memory, getting better sleep, or eliminating problem
behaviors such as procrastination. As you will see, Psychology Matters!
Check Your Understanding
1. RECALL: What is the difference between a scientific theory and a
mere opinion?
2. APPLICATION: Which of the following could be an operational
definition of “fear”?
a. an intense feeling of terror and dread when thinking about some
threatening situation
b. panic
c. a desire to avoid something
d. moving away from a stimulus
3. ANALYSIS: Identify the only form of research that can determine
cause and effect. Why is this so?
4. ANALYSIS: Why would an experimenter randomly assign
participants to different experimental conditions?
5. ANALYSIS: Which one of the following correlations shows the
strongest relationship between two variables?
a. +0.4
b. +0.38
c. −0.7
d. 0.05
6. ANALYSIS: What would be a good method for controlling
expectancy bias in research on a new drug for depression?
7. RECALL: Why does research using deception pose an ethical
problem?
8. UNDERSTANDING THE CORE CONCEPT: What do scientists
mean by empirical observation?
Answers 1. A scientific theory is a testable explanation for available facts or observations. An opinion is not necessarily testable, nor can it generally
explain all the relevant information. 2. d. (because it is the only one phrased in terms of behaviors that can be observed objectively) 3. Only the
experiment can determine cause and effect, because it is the only method that manipulates the independent variable. 4. Random assignment helps
ensure that the experimental and control groups are comparable. 5. c. 6. A double-blind study, because it controls for the expectations of both the
experimenters and the participants who receive the drug. 7. Deception involves a conflict with the principle that participants in research should give
their informed consent. (Deception is, however, permitted under certain circumstances specified in the Ethical Principles document.) 8. Empirical
observation requires making careful measurements based on direct experience.
Study and Review at MyPsychLab

How Do Psychologists Develop New Knowledge? 35
CRITICAL THINKING APPLIED
Facilitated Communication
A utism is a developmental disorder that can cause severe impairments in attention, cognition, communication,
and social functioning. In the most extreme forms, persons
with autism often seem encapsulated in their own worlds,
disconnected from people around them. Consequently,
working with them can sometimes be quite discouraging for
parents and teachers alike. It is no wonder, then, that a tech-
nique known as facilitated communication was heralded as
a dramatic breakthrough in the treatment of autism.
Facilitated communication rests on the belief that untapped
language abilities lie hidden by the mask of autism. Propo-
nents of this technique use a trained facilitator to see through
the mask by helping the person with autism answer questions
by pointing to letters on a letter board or keyboard. (You can
see how this is done in the accompanying photo.) Parents and
teachers welcomed the initial enthusiastic reports on facilitated
communication. But would those reports withstand the scru-
tiny of science?
What Are the Critical Issues?
On its face, the claim that a person with autism is, somehow,
ready but unable to communicate is quite appealing to anyone
personally involved in the issue—after all, communication is a
basic element of human relationships. But many psychologists re-
mained skeptical. What critical thinking questions did they ask?
Is the Claim Reasonable or Extreme? The notion that a
simple pointing technique could break through the barrier of
autism sounded too good to be true, said critics. Indeed, such
extreme claims are typically a cue for critical thinkers to exam-
ine the claim and the evidence more closely. Testimonials, no
matter how powerful, are no substitute for empirical evidence.
What Is the Evidence? Sure enough, evidence from scientific
studies showed that, when the facilitator knew the questions, the
child with autism would appear to give sensible answers. But
when “blinders” were applied—by hiding the questions from
the facilitator—the responses were inaccurate or nonsensical
(American Psychological Association, 2003d; Lilienfeld, 2007).
Could Bias Contaminate the Conclusion? The evidence
above reveals one form of bias you may have already suspected:
The helper was—consciously or unconsciously—guiding the
child’s hand to produce the messages. This expectancy bias
became apparent when erroneous responses emerged under
conditions where the facilitator didn’t know the question. Con-
firmation bias and emotional biases were undoubtedly at work,
Autism A developmental disorder marked by disabilities in language, social interaction,
and the ability to understand another person’s state of mind.
too: Parents and teachers, desperate for an effective treatment,
uncritically accepted the anecdotal reports of success.
What Conclusions Can We Draw?
Sadly, although facilitated communication had extended hope to
beleaguered parents and teachers, a scientific look presented a pic-
ture showing how uncritical belief could create consequences far
worse than false hopes. More effective treatments were delayed,
and moreover, parents blamed themselves when their children did
not respond to the treatment as expected (Levine et al., 1994).
Worst of all were the false accusations of sexual abuse based on
messages thought to have come from children with autism (Bick-
len, 1990; Heckler, 1994). The research left little doubt, however,
that these messages had originated wholly in the minds of the
facilitators. In light of such findings, the American Psychological
Association (2003b) denounced facilitated communication as a
failure and relegated it to the junk pile of ineffective therapies.
What lessons about critical thinking can you, as a student
of psychology, take away from the facilitated communica-
tion fiasco? We hope you will develop a skeptical attitude
about reports of extraordinary new treatments, dramatic
psychological breakthroughs, and products that claim to help
you develop untapped potential. And we hope you will al-
ways pause to ask: What is the evidence? Could the claims
be merely the result of people’s expectations? Perhaps the big
lesson to be learned is this: No matter how much you want to
believe, and no matter how many anecdotes and testimonials
you have, there is no substitute for empirical evidence.
When skeptical psychologists tested the claims for facilitated com-
munication, they found that it wasn’t the autistic children who were
responsible for the messages.

36 C H A P T E R 1 Mind, Behavior, and Psychological Science
CHALLENGING YOUR OWN PSEUDOSCIENTIFIC BELIEFS
By now, you probably recognize that
everyone—even well-trained scientists—
risks falling prey to biases and pseudosci-
ence. Thus, we hope you will accept that
you, too, are vulnerable to these errors in
logic. Here, we list several popular beliefs
that—yes, you guessed it—do not hold up
to scientific scrutiny. Choose one that you
tend to believe and use the Internet to find
reports of scientific studies of the belief.
Then identify at least two of the critical
thinking guidelines that you violated when
you believed that myth to be true. Then,
share your findings with your classmates.
Popular Pseudoscientific Myths
Crime rates increase when the moon
is full.
Venting anger is healthy.
Abused children become abusive adults.
Most people repress traumatic memories.
If you believe in yourself, you can do
anything (or, Visualize success and
you’ll achieve it).
People who join cults are weak-
minded or lack intelligence.
If you’re depressed, think happy
thoughts and you’ll feel better.
CHAPTER SUMMARY
PROBLEM: How would psychology test the claim that sugar
makes children hyperactive?
• Psychologists would use the scientific method to test this claim.
• In a controlled experiment—designed to show cause-
and-effect—children would be assigned randomly to an
experimental group or a control group and given a drink with
sugar or a sugar substitute.
• Using a double-blind procedure to control for experimenter
bias and the placebo effect, observers would rate each child’s
activity level.
• Analyzing the resulting data would show whether or not the
hypothesis had been supported. If children who received the
sugared drink were more active, we could conclude that sugar
does make children hyperactive.
1.1 What Is Psychology—and What Is It Not?
Core Concept 1.1 Psychology is a broad field with many
specialties, but fundamentally, psychology is the science of
behavior and mental processes.
All psychologists are concerned with some aspect of behavior
and mental processes. Unlike the pseudosciences, scientific psy-
chology demands solid evidence to back up its claims. Within
psychology, there are many specialties that fall within three
broad areas. Experimental psychologists primarily do research
but often teach as well. Those who are primarily teachers of
psychology work in a variety of settings, including colleges, uni-
versities, and high schools. Applied psychologists practice many
specialties, such as industrial/organizational, sports, school,
rehabilitation, clinical and counseling, forensic, and environ-
mental psychology. In contrast with psychology, psychiatry is a
medical specialty that deals exclusively with mental disorders.
In the media, much of what appears to be psychology is
actually pseudo-psychology. Noticing the difference requires
development of critical thinking skills—which this book
organizes around six questions to ask when confronting
new claims that purport to be scientifically based:
• What is the source?
• Is the claim reasonable or extreme?
• What is the evidence?
• Could bias contaminate the conclusion?
• Does the reasoning avoid common fallacies?
• Does the issue require multiple perspectives?
anecdotal evidence (p. 8)
applied psychologists (p. 5)
confirmation bias (p. 8)
critical thinking skills (p. 7)
emotional bias (p. 8)
experimental psychologists (p. 5)
pseudo-psychology (p. 7)
psychiatry (p. 6)
psychology (p. 4)
teachers of psychology (p. 5)
Listen at MyPsychLabto an audio file of your chapter

Chapter Summary 37
1.2 What Are Psychology’s Six Main
Perspectives?
Core Concept 1.2 Six main viewpoints dominate modern
psychology—the biological, cognitive, behavioral, whole-
person, developmental, and sociocultural perspectives—each
of which grew out of radical new concepts about mind and
behavior.
Psychology’s roots stretch back to the ancient Greeks. Several
hundred years ago, René Descartes helped the study of the
mind to become scientific, based on his assertion that sen-
sations and behaviors are linked to activity in the nervous
system—a step that ultimately led to the modern biological
perspective, which looks for the causes of behavior in physi-
cal processes such as brain function and genetics. Biological
psychology itself has developed in two directions: the fields of
neuroscience and evolutionary psychology.
The formal beginning of psychology as a science, how-
ever, is traced to the establishment by Wundt of the first psy-
chological laboratory in 1879. Wundt’s psychology, which
American psychologists morphed into structuralism, advo-
cated understanding mental processes such as consciousness
by investigating their contents and structure. Another early
school of psychology, known as functionalism, argued that
mental processes are best understood in terms of their adap-
tive purposes and functions. Both were criticized for the use
of introspection, which some psychologists found too subjec-
tive. Nevertheless, elements of these schools can be found in
the modern cognitive perspective, with its interest in learning,
memory, sensation, perception, language, and thinking and
its emphasis on information processing.
The behavioral perspective emerged around 1900, reject-
ing the introspective method and mentalistic explanations,
choosing instead to analyze behavior in terms of observable
stimuli and responses. Proponents of behaviorism, such as
John Watson and B. F. Skinner, have exerted a powerful influ-
ence on modern psychology with their demands for objective
methods, insights into the nature of learning, and effective
techniques for management of undesirable behavior.
Three rather different viewpoints make up the whole-person
perspective, which takes a global view of the individual. Sigmund
Freud’s psychoanalytic approach, with its focus on mental
disorder and unconscious processes, led to psychoanalysis and
modern psychodynamic psychology. In contrast, humanistic psychol-
ogy, led by Abraham Maslow and Carl Rogers, emphasizes the
positive side of human nature. Meanwhile, trait and temperament
psychology sees people in terms of their persistent characteristics
and dispositions.
The developmental perspective calls attention to mental and
behavioral changes that occur predictably throughout the
lifespan. Such changes result from the interaction of hered-
ity and environment. Alternatively, the sociocultural perspective
argues that each individual is influenced by other people and
by the culture in which they are all embedded.
Modern psychology has changed rapidly over the past
decades as the biological, cognitive, and developmental
perspectives have become dominant. At the same time,
adherents of different perspectives are joining forces. Another
major change involves the increasing number of women and
minority-group members entering the field.
While careers in psychology are available at various edu-
cational levels, becoming a fully fledged psychologist requires
a doctorate. Those with less than a doctorate work in various
applied specialties as aides, teachers, and counselors.
behavioral perspective (p. 17)
behaviorism (p. 16)
biological perspective (p. 12)
cognitive perspective (p. 15)
cross-cultural psychologists (p. 20)
culture (p. 20)
developmental perspective (p. 19)
evolutionary psychology (p. 13)
functionalism (p. 14)
humanistic psychology (p. 18)
introspection (p. 13)
Necker cube (p. 15)
neuroscience (p. 13)
psychoanalysis (p. 18)
psychodynamic psychology (p. 17)
sociocultural perspective (p. 19)
structuralism (p. 14)
trait and temperament psychology (p. 18)
whole-person perspectives (p. 18)
Research utilizing this scientific method can employ experi-
ments, correlational studies, surveys, naturalistic observations, and
case studies. Each method differs in the amount of control
the researcher has over the conditions being investigated. Re-
searchers can fall prey to expectancy bias. One way scientists
control for bias in their studies is the double-blind method.
Using the experimental method in large and well-controlled
double-blind studies, researchers have failed to find evidence
that links sugar to hyperactivity in children.
1.3 How Do Psychologists Develop New
Knowledge?
Core Concept 1.3 Psychologists, like all other scientists,
use the scientific method to test their ideas empirically.
Psychology differs from the pseudosciences in that it employs
the scientific method to test its ideas empirically. The scientific
method relies on testable theories and falsifiable hypotheses.

38 C H A P T E R 1 Mind, Behavior, and Psychological Science
CRITICAL THINKING APPLIED
however, experimental studies revealed that reports of success
were skewed by expectancy bias. As a result, facilitated com-
munication was denounced by the American Psychological
Association.
Facilitated Communication
A form of therapy known as facilitated communication was
originally touted as a revolutionary new method of commu-
nicating with persons with autism. Upon closer inspection,
DISCOVERING PSYCHOLOGY VIEWING GUIDE
Watch the following videos by logging into MyPsychLab (www.mypsychlab.com).
After you have watched the videos, answer the questions that follow.
PROGRAM 1: PAST, PRESENT,
AND PROMISE
PROGRAM 2: UNDERSTANDING
RESEARCH
c. the scientific study of the behavior of individuals and of their
mental processes
d. the knowledge used to predict how virtually any organism will
behave under specified conditions
Program Review
1. What is the best definition of psychology?
a. the scientific study of how people interact in social groups
b. the philosophy explaining the relation between brain
and mind
Psychologists follow a code of ethics, established by the
American Psychological Association, for the humane treat-
ment of subjects. Still, some areas of disagreement remain.
These especially involve the use of deception and the use of
animals as experimental subjects.
Despite widespread acceptance of the scientific method,
pseudo-psychological claims abound. Unchecked, pseudo-
psychology can have harmful effects, as seen in the use of the
lobotomy.
case study (p. 31)
control group (p. 27)
correlational study (p. 28)
data (p. 26)
dependent variable (p. 27)
double-blind study (p. 32)
empirical investigation (p. 24)
expectancy bias (p. 31)
experiment (p. 27)
experimental group (p. 27)
hypothesis (p. 24)
independent variable (p. 27)
informed consent (p. 32)
naturalistic observation (p. 30)
negative correlation (p. 29)
operational definitions (p. 24)
placebo (p. 32)
positive correlation (p. 28)
random assignment (p. 28)
replicate (p. 26)
scientific method (p. 24)
survey (p. 30)
theory (p. 24)
zero correlation (p. 29)

www.mypsychlab.com

Discovering Psychology Viewing Guide 39
2. What is the main goal of psychological research?
a. to cure mental illness
b. to find the biological bases of the behavior of organisms
c. to predict and, in some cases, control behavior
d. to provide valid legal testimony
3. Who founded the first psychology laboratory in the
United States?
a. Wilhelm Wundt
b. William James
c. G. Stanley Hall
d. Sigmund Freud
4. Which of the following is desirable in research?
a. having the control and experimental conditions differ on
several variables
b. interpreting correlation as implying causality
c. systematic manipulation of the variable(s) of interest
d. using samples of participants who are more capable than the
population you want to draw conclusions about
5. What is the main reason the results of research studies are published?
a. so researchers can prove they earned their money
b. so other researchers can try to replicate the work
c. so the general public can understand the importance of
spending money on research
d. so attempts at fraud and trickery are detected
6. Why does the placebo effect work?
a. because researchers believe it does
b. because participants believe in the power of the placebo
c. because human beings prefer feeling they are in control
d. because it is part of the scientific method
7. What is the purpose of a double-blind procedure?
a. to test more than one variable at a time
b. to repeat the results of previously published work
c. to define a hypothesis clearly before it is tested
d. to eliminate experimenter bias
8. A prediction of how two or more variables are likely to be related
is called a
a. theory.
b. conclusion.
c. hypothesis.
d. correlation.
9. Why would other scientists want to replicate an experiment that
has already been done?
a. to have their names associated with a well-known
phenomenon
b. to gain a high-odds, low-risk publication
c. to ensure that the phenomenon under study is real and
reliable
d. to calibrate their equipment with that of another laboratory
10. The reactions of the boys and the girls to the teacher in the
Candid Camera episode were essentially similar. Professor
Zimbardo attributes this reaction to
a. how easily adolescents become embarrassed.
b. how an attractive teacher violates expectations.
c. the way sexual titillation makes people act.
d. the need people have to hide their real reactions.
11. The amygdala is an area of the brain that processes
a. sound.
b. social status.
c. faces.
d. emotion.
12. What assumption underlies the use of reaction times to study
prejudice indirectly?
a. People of different ethnic backgrounds are quicker intellectu-
ally than people of other ethnicities.
b. Concepts that are associated more strongly in memory are veri-
fied more quickly.
c. Prejudice can’t be studied in any other way.
d. People respond to emotional memories more slowly than
emotionless memories.

2.2 How Does the Body Communicate
Internally?
The Neuron: Building Block of the
Nervous System
The Nervous System
The Endocrine System
2.1 How Are Genes and Behavior
Linked?
Evolution and Natural Selection
Genetics and Inheritance
Biopsychology, Neuroscience,
and Human Nature2
Psychology MattersCore ConceptsKey Questions/Chapter Outline
Evolution has fundamentally shaped
psychological processes because it
favors genetic variations that produce
adaptive behavior.
Choosing Your Children’s Genes
Within your lifetime, parents may be
able to select genetic traits for their
children. What price will we pay for
these choices?
The brain coordinates the body’s
two communications systems, the
nervous system and the endocrine
system, which use similar chemical
processes to communicate with targets
throughout the body.
How Psychoactive Drugs Affect
the Nervous System
Chemicals used to alter thoughts and
feelings usually affect the actions
of hormones or neurotransmitters.
In so doing, they may also stimulate
unintended targets, producing
unwanted side effects.
The brain is composed of many
specialized modules that work together
to create mind and behavior.
Using Psychology to Learn
Psychology
The fact that we employ many
different regions of the cerebral
cortex in learning and memory may be
among neuroscience’s most practical
discoveries.
CHAPTER PROBLEM What does Jill Bolte Taylor’s experience teach us about how our brain is
organized and about its amazing ability to adapt?
CRITICAL THINKING APPLIED Left Brain versus Right Brain
2.3 How Does the Brain Produce
Behavior and Mental Processes?
Windows on the Brain
Three Layers of the Brain
Lobes of the Cerebral Cortex
Cerebral Dominance

41
I WAS LIVING LARGE,” SAYS DR. JILL BOLTE TAYLOR, ALSO KNOWN AS THE Singing Scientist (Taylor, 2009, p. xiv). At age 37, the Harvard Medical School brain anatomist had won prestigious awards and was recognized nationwide for her breakthrough research on the brain’s involvement in mental illness. Then, on a cold
December morning, her life abruptly changed.
When Jill first awoke that fateful day, she noticed a painful pounding in her head that felt
like a severe headache. As she tried to go about her normal morning routine, however, she
began to notice odd changes in her body and her mind. Stepping into the shower became a fo-
cused effort in coordination. Her body felt strange; the sound of the water was a deafening roar,
and the overhead light seared her eyes. As she tried to think rationally and figure out what was
happening, she couldn’t keep her thoughts on track. Instead, she found herself irresistibly dis-
tracted by a newfound fascination with the movement of her body parts. “As I held my hands
up in front of my face and wiggled my fingers, I was simultaneously perplexed and intrigued.
Wow, what a strange and amazing thing I am . . . I was both fascinated and humbled by how
hard my little cells worked, moment by moment . . . I felt ethereal” (pp. 42–43). Then, her right
arm became paralyzed, and suddenly she knew: “Oh my gosh, I’m having a stroke!”—followed
immediately by something perhaps only a brain scientist would consider at a time like that,
“Wow, this is so cool!” (p. 44).
Over the next few hours, Jill struggled with figuring out how to get help. She was no longer
aware that calling 911 would bring emergency treatment, nor could she recognize the numbers
on a telephone keypad. When—after spending a full hour figuring out how to call for help—she
finally reached a coworker, she discovered that not only did she not understand his words,
“

he could not understand hers: She had lost her ability to speak and to understand language.
Fortunately, her coworker recognized her voice, but the several hours it took for Jill to get to a
hospital took a profound toll on her brain. She could not sit up or walk without assistance. She
could hear, but sounds were merely noise; she could not make sense out of them. She could
see but could not distinguish color or determine whether a crack in the sidewalk was danger-
ous. She could not communicate with others. She didn’t even recognize her own mother. The
massive stroke she had suffered spilled blood throughout the left side of her brain, creating a
toxic environment for millions of brain cells.
Remarkably, though, Jill recovered. Despite the extensive damage to her brain, she has
returned to her career as a neuroanatomist, teaching at Indiana University School of Medicine
and traveling as a national spokesperson for the Harvard Brain Bank. She water skis, plays
guitar, and creates works of art that are uniquely representative of her experiences: anatomi-
cally correct stained glass brains. On the outside, observers see no signs of the traumatic brain
injury she survived. On the inside, however, Jill is not the same person. Her injury and recovery
rewired her brain, and with the rewiring came a different perspective on life and different per-
sonality traits. “I may look like me, and I may sound like me, but I’m different now, and I had
to accept that,” she states with grace and conviction. “I believe [Einstein] got it right when he
said, ‘I must be willing to give up what I am in order to become what I will be’” (p. 185).
PROBLEM: What does Jill’s experience teach us about how our brain is organized and
about its amazing ability to adapt?
What do we know about the human brain? In simplest terms, it is about the size of a grapefruit,
it weighs about 3 pounds, and it has a pinkish-gray and wrinkled surface. But such bald facts
offer no hint of the brain’s amazing structure and capabilities. Some 100 billion neurons (nerve
cells), each connecting with up to 10,000 other neurons, make the human brain the most com-
plex structure known. Our largest computers seem primitive by comparison.
At birth, you actually had far more neurons than you do now. Many of them have been
pruned away, probably from disuse in the first few years of your life. (Don’t worry. It
happens to everyone!) In adolescence, the number stabilizes and then remains essen-
tially the same throughout adulthood as some cells die and others develop on a daily
basis (Gage, 2003).
As for its capabilities, the human brain uses its vast nerve circuitry to regulate all
our body functions, control our behavior, generate our emotions and desires, and pro-
cess the experiences of a lifetime. Most of this activity operates unconsciously behind
the scenes—much like the electronics in your TV. Yet when disease, drugs, or accidents
destroy brain cells, the biological basis of the human mind becomes starkly apparent.
Then we realize the critical role of biology in human sensation and perception, learn-
ing and memory, passion and pain, reason—and even madness.
Most remarkable of all, perhaps, the human brain has the ability to think about
itself. This fact fascinates specialists in biopsychology, who work in a rapidly growing
field that lies at the intersection of biology, behavior, and mental processes. Biopsy-
chologists often collaborate with cognitive psychologists, biologists, computer scien-
tists, chemists, neurologists, linguists, and others interested in the connection between
brain and mind. The result is a vibrant interdisciplinary field known as neuroscience
(Kandel & Squire, 2000).
Looking at mind and behavior from this biological perspective has produced many
practical applications. For example, we now know that certain parts of the brain
control sleep patterns—with the result that we now have effective treatments for a
number of formerly untreatable sleep disorders. Likewise, the effects of certain psycho-
active drugs, such as cocaine, heroin, and methamphetamine, make sense now that we
biopsychology The specialty in psychology that
studies the interaction of biology, behavior, and mental
processes.
C O N N E C T I O N CHAPTER 1
Neuroscience grew out of
the biological perspective in
psychology, which looks for
physiological explanations for
human behavior and mental
processes (p. 13).
42 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature

How Are Genes and Behavior Linked? 43
understand how these drugs interact with chemicals produced by the brain. And, as we
will see, recent discoveries involving mirror neurons, the genetic code for human life,
brain implants, and the biological basis of memory promise many more benefits for
people who live with brain disease.
We begin our exploration of biopsychology and neuroscience at the most basic
level—by considering the twin domains of genetics and evolution, both of which have
shaped our bodies and minds. Then we will examine the endocrine system and the
nervous system, the two communication channels carrying messages throughout the
body. Finally, we will focus on the brain itself. By reading this chapter, you will come to
understand how Jill Bolte Taylor recovered from the massive damage to her brain, yet
became an essentially different person. More importantly, you will learn how biologi-
cal processes shape your every thought, feeling, and action.
2.1 KEY QUESTION
How Are Genes and Behavior Linked?
Just as fish have an inborn knack for swimming and most birds are built for flight, we
humans also have innate (inborn) abilities. At birth, the human brain emerges already
“programmed” for language, social interaction, self-preservation, and many other
functions—as we can readily see in the interaction between babies and their caregivers.
Babies “know,” for example, how to search for the breast, how to communicate rather
effectively through coos and cries and, surprisingly, how to imitate a person sticking
out her tongue. We’ll look more closely at the menu of innate human behaviors in our
discussion of human development (Chapter 7), but for now, this is the question: How
did such potential come to be woven into the brain’s fabric?
The scientific answer rests on the concept of evolution, the process by which suc-
ceeding generations of organisms change as they adapt to changing environments. We
can observe evolution in action on a microscopic level, when an antibiotic fails to
work on a strain of bacteria that has evolved a resistance. When it comes to larger and
more complex organisms, change occurs over much longer periods of time as these
organisms adapt to changing climates, predators, diseases, and food supplies. In our
own species, for example, change has favored large brains suited to language, complex
problem solving, and social interaction.
Our Core Concept for this section makes this evolutionary process the link between
genetics and behavior.
Core Concept 2.1
Evolution has fundamentally shaped psychological processes because
it favors genetic variations that produce adaptive behavior.
Our explanation of evolution begins in this section with the story of Charles Darwin,
who gave the idea of evolutionary change to the world. Following that, we will build
on Darwin’s insight with a look at genetics, which involves the molecular machinery
that makes evolution work—and ultimately influences all our thoughts and behaviors.
Evolution and Natural Selection
Although he trained for careers in both medicine and the ministry, Charles Darwin’s
greatest love was nature. He was thrilled, then, when in 1831 (with help from his
botany professor) he landed a job as a “gentleman companion” aboard the Beagle
(Phelan, 2009), a British research vessel surveying the coastline of South America.
Darwin quickly became seasick, however, which made being on the ship unbearable,
so he spent as much time as possible on land. Following his passion, he began studying
the native species, collecting numerous specimens and keeping detailed records of the
evolution The gradual process of biological
change that occurs in a species as it adapts to its
environment.

44 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
unusual life-forms he found. Struck by the similarities among the various animals and
plants he studied, Darwin wondered if they could possibly be related to each other, and
furthermore, if all creatures, including humans, might share a common ancestry.
He knew this notion flew in the face of accepted scholarship, as well as the reli-
gious doctrine of creationism. So, in his famous book, On the Origin of Species (1859),
Darwin carefully made the case for the evolution of life. And controversial it was. The
essential features of his argument, however, withstood withering attacks, and eventu-
ally his theory of evolution created a fundamental change in the way people saw their
relationship to other living things (Keynes, 2002; Mayr, 2000).
The Evidence That Convinced Darwin What was the evidence that led Darwin to his
radical conclusion about the evolution of organisms? Again and again on the voyage,
he observed organisms exquisitely adapted to their environments: flowers that attracted
certain insects, birds with beaks perfectly suited to cracking certain types of seeds. But
he also observed variation among individuals within a species—just as some humans
are taller than others or have better eyesight (Weiner, 1994). It occurred to Darwin that
such variations could give one individual an advantage over others in the struggle for
survival and reproduction. This, then, suggested a mechanism for evolution: a “weeding
out” process he called natural selection. By means of natural selection, those individuals
best adapted to their environment are more likely to flourish and reproduce; the poorly
adapted tend to leave fewer offspring, and their line may die out. (You may have heard
this described as survival of the fittest, a term Darwin disliked.) Through natural selec-
tion, then, a species gradually changes as it adapts to the demands of its environment.
Application to Psychology This process of adaptation and evolution helps us make
sense of many observations we make in psychology. For example, human phobias
(extreme and incapacitating fears) most often involve stimuli that signaled danger to
our ancestors, such as snakes, heights, and lightning (Hersen & Thomas, 2005). In
the same way, the fact that we spend about a third of our lives asleep makes sense
in evolutionary terms: Sleep kept our ancestors out of trouble in the dark. Evolution
also explains our innate preferences and distastes, such as the attractiveness of sweets
and fatty foods (good sources of valuable calories for our ancestors) and a dislike for
bitter-tasting substances (often signaling poisons).
Evolution is, of course, an emotionally loaded term and, as a result, many people
have a distorted understanding of its real meaning. For example, some believe that
Darwin’s theory says humans “come from monkeys.” But neither Darwin nor any
other evolutionary scientist has ever said that. Rather, they say people and monkeys
had a common ancestor millions of years ago—a big difference. Evolutionary theory
says that, over time, the two species have diverged, each developing different sets of
adaptive traits. For humans, this meant developing a big brain adapted for language
(Buss et al., 1998).
We should be clear that the basic principles of evolution, while still controversial
in some quarters, have been accepted by virtually all scientists for more than a century.
That said, we should also note that evolutionary theory is a controversial newcomer
to psychology. It is not that psychologists dispute Darwin—most do not. To its credit,
evolutionary psychology may provide an elegant solution to the nature–nurture de-
bate, which we learned about in Chapter 1, by its premise that behavior evolves from
the interaction of heredity and environmental demands (Yee, 1995). Some worry, how-
ever, that recognition of a prominent genetic role in behavior may raise the question of
whether genetics absolves us of our responsibility for troublesome behaviors such as
aggression or addiction—a question to which evolutionary psychologists resoundingly
reply, “No!” (Hagen, 2004).
In later chapters, we will discuss specific evolutionary theories that have been
advanced to explain aggression, jealousy, sexual orientation, physical attraction
and mate selection, parenting, cooperation, temperament, morality, and (always a
psychological hot potato) gender differences. But for now, let us turn our attention to
genetics and the biological underpinnings of heredity and evolutionary change.
natural selection The driving force behind
evolution by which the environment “selects” the fittest
organisms.

How Are Genes and Behavior Linked? 45
Genetics and Inheritance
In principle, the genetic code is quite simple. Much as the microscopic pits in a CD encode
information that can become pictures or music, your genes encode molecular informa-
tion that can become inherited traits. Consider your own unique combination of physical
characteristics. Your height, facial features, and hair color, for example, all stem from the
encoded genetic “blueprint” inherited from your parents and inscribed in every cell
in your body. Likewise, genetics influences psychological characteristics, including your
basic temperament, tendency to fears, and certain behavior patterns (Pinker, 2002).
Yet, even under the influence of heredity, you are a unique individual, different from
either of your parents. One source of your uniqueness lies in your experience: the envi-
ronment in which you grew up—distinct in time and, perhaps, in place from that of your
parents. Another source of difference between you and either of your parents arises from
the random combination of traits, both physical and psychological, each parent passed
on to you from past generations in their own family lines. (It is important to note you
do not inherit copies of all your father’s and mother’s genes. Rather, you get half of each,
randomly shuffled.) This hybrid inheritance produced your unique genotype, the genetic
pattern that makes you different from anyone else on earth. Still, as different as people
may seem, 99.9 percent of human genetic material is the same (Marks, 2004).
If the genotype is the “blueprint,” then the resulting structure is the phenotype. All
your physical characteristics make up your phenotype, including not only your visible
traits (for instance, the shape of your nose or the number of freckles you have) but
also “hidden” biological traits, such as the chemistry and “wiring” of your brain. In
fact, any observable characteristic is part of the phenotype—so the phenotype includes
behavior. We should quickly point out that, while the phenotype is based in biology, it
is not completely determined by heredity. Heredity never acts alone but always in part-
nership with the environment, which includes such biological influences as nutrition,
disease, stress, and experiences that leave a lasting mark in the form of learning. The
environment even plays a role before our birth, such as when poor medical care results
in a birth defect.
Now, with these ideas about heredity, environment, genotypes, and phenotypes
fresh in mind, let’s turn to the details of heredity and individual variation that were yet
to be discovered in Darwin’s time.
Chromosomes, Genes, and DNA The blockbuster film Jurassic Park and its sequels
relied on a clever twist of plot in which scientists recovered the genetic code for dino-
saurs and created an island full of reptilian horrors. The stories, of course, are science
C O N N E C T I O N CHAPTER 10
Infants differ in their tendency
to be shy or outgoing, which
is believed to be an aspect of
temperament with a strong
biological basis (p. 421).
genotype An organism’s genetic makeup.
phenotype An organism’s observable physical and
behavioral characteristics.
More than 98 percent of our genetic
material is also found in chimpanzees
(Pennisi, 2007). This supports Darwin’s
idea that humans and apes had a
common ancestor.

46 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
fiction, yet the films rest on an important scientific fact: Every cell in the body carries a
complete set of biological instructions, known as a genome, for building the organism.
For humans, these instructions are spelled out in 23 pairs of chromosomes, which, un-
der a high-powered microscope, look like tiny twisted threads. Zooming in for an even
closer look, we find that each chromosome consists of a long and tightly coiled chain
of DNA (deoxyribonucleic acid), a molecule especially well suited for storing biological
information (see Figure 2.1).
Genes are the “words” that make up each organism’s instruction manual. Encoded
in short segments of DNA, each gene contributes to the operation of an organism by
specifying a single protein. Thousands of such proteins, in turn, serve as the build-
ing blocks for the organism’s physical characteristics (part of the phenotype) and the
regulation of the body’s internal operations. Genes, because they differ slightly from
one individual to another, provide the biological source for the variation that caught
Darwin’s attention.
Like the string of words in this paragraph, genes occur in sequence on the chromo-
somes. But chromosomes are much more than strings of genes. Like paragraphs, they
also contain “punctuation” that indicates where each gene begins and ends, along with
commands specifying how and when the genes will be expressed (Gibbs, 2003). Some-
times, however, these commands are wrong, or the genes themselves have defects. The
resulting errors in gene expression can cause physical and developmental problems,
such as cerebral palsy and mental retardation.
On a still smaller scale, genes are composed of even tinier molecular units called nu-
cleotides that serve as individual “letters” in the genetic “words.” Instead of a 26-letter
alphabet, the genetic code uses just four nucleotides. Consequently, a particular gene
may require hundreds of nucleotides strung together in a unique pattern to specify a
particular protein. You can see why, then, the Human Genome Project is so exciting
to scientists: It mapped the complete nucleotide pattern for all of the approximately
30,000 genes in the human organism, including multiple variations of patterns on each
gene to account for individual differences! Results offer great hope for better under-
standing and treatment of physical and psychological disorders.
Of the 46 chromosomes (23 pairs), two warrant special mention: the sex chromosomes.
Named X and Y for their shapes, these chromosomes carry genetic encoding for a male
or female phenotype. We all inherit one X chromosome from our biological mothers.
genome The complete set of genetic information
contained within a cell.
DNA (deoxyribonucleic acid) A long, com-
plex molecule that encodes genetic characteristics.
gene Segment of a chromosome that encodes the
directions for the inherited physical and mental char-
acteristics of an organism. Genes are the functional
units of a chromosome.
chromosome Tightly coiled threadlike structure
along which the genes are organized, like beads on a
necklace. Chromosomes consist primarily of DNA.
sex chromosomes The X and Y chromosomes
that determine our physical sex characteristics.
Genes contain
instructions
for making
proteins.G
C
C
C
G
C
G
T
A G A
T
A
T
A
T
T
A
Cell
Genome
DNA
Chromosome
Genes
FIGURE 2.1
DNA, Genes, and Chromosomes
A chromosome is composed mainly of a tightly coiled strand of DNA, an incredibly long molecule.
Each chromosome contains thousands of genes, along with instructions for the “when” and “how”
of gene expression, which together represent the organism’s genome. Genes themselves are seg-
ments of DNA. Each gene contains instructions, coded in the four-nucleotide alphabet, for making
a protein. The Human Genome Project has identified the sequence of nucleotides in all 23 pairs of
our chromosomes.
Read
MyPsychLab
about How DNA Works at

How Are Genes and Behavior Linked? 47
In addition, we receive either an X or a Y from our biological fathers. When they pair up,
two X chromosomes (XX) contain the code for femaleness, while an XY pair codes for
maleness. In this sense, then, the chromosome we get from our fathers—either an X or
a Y—determines our biological sex.
Genetic Explanations for Psychological Processes Most of our discussion of he-
redity and genetics could apply equally to fruit flies and butterflies, hollyhocks and
humans. All organisms follow the same basic laws of heredity. The differences among
species arise, then, from different genetic “words”—the genes themselves—“spelled”
with the same four letters (nucleotides) of life’s universal four-letter alphabet.
And what does all this have to do with psychology? Simply put, genes influence our
psychological characteristics just as they do our physical traits. In later chapters, we
will explore how genes affect such diverse human attributes as intelligence, personality,
mental disorders, reading and language disabilities, and (perhaps) sexual orientation.
Even our fears can have some genetic basis (Hariri et al., 2002). But, because genetic
psychology is still a field in its infancy, we don’t yet know exactly how or to what ex-
tent specific genes are involved in most psychological processes (Rutter, 2006).
It is also important to note that multiple genes, rather than just one, are thought to
be involved in most disorders (Plomin, 2000). In only a few cases can we hold a single
gene responsible for a specific psychological disorder. For example, just one abnormal
gene has been linked to a rare pattern of impulsive violence found in several members
of a Dutch family (Brunner et al., 1993). Experts expect that multiple genes contrib-
ute to most other conditions such as schizophrenia, a severe mental disorder, and
Alzheimer’s disease, a form of dementia. (St. George-Hyslop, 2000).
So, does this mean that heredity determines our psychological destiny? Will you grow
up to be like your Uncle Henry? Not to worry. Although you may share many of his
genes, your heredity never acts alone. Heredity and environment always work together
to influence our behavior and mental processes (Pinker, 2002). Jill Bolte Taylor’s intel-
ligence, for example, has a genetic component (her mother went to Harvard and her
father has a doctoral degree) but was further nurtured in her childhood environment and
educational opportunities. Her ability to overcome the challenges of her severe medical
condition, construct a new life, and go on to become one of Time Magazine’s 100 Most
Influential People in the World (2008) illustrates her creativity, a trait she attributes to
her father—but also undoubtedly enhanced by her training as a scientist.
Even identical twins, who share the same genotype, display individual differences
in appearance and personality that result from their distinct experiences, such as expo-
sure to different people, places, chemicals, and diseases. Moreover, studies show that
when one identical twin acquires a psychological disorder known to have a genetic
basis (schizophrenia, for example), the other does not necessarily develop the same
disorder. The takeaway message is this: Never attribute psychological characteristics to
genetics alone (Ehrlich, 2000a, b; Mauron, 2001).
A final example of the interaction between heredity and environment—and one
of the rays of hope from biopsychology—can be seen in a condition called Down
syndrome. Associated with an extra chromosome 21, this disorder includes impaired
physical development as well as mental retardation. Only a few years ago, people with
Down syndrome faced bleak and unproductive lives, shut away in institutions where
they depended almost wholly on others to fulfill their basic needs. Now, a better under-
standing of the disorder, along with a deeper appreciation for the interaction between
genetics and environment, has changed that outlook. Although no cure has been found,
today we know that people with Down syndrome are capable of considerable learning
despite their genetic impairment. With special life skills training, those with Down syn-
drome learn to care for themselves, work, and establish some personal independence.
In this way, environmental factors can powerfully shape genetic dispositions.
“Race” and Human Variation Certain features of skin color and other physical
characteristics are more (or less) common among people who trace their ancestry to
the same part of the world. Tropical ancestry is often associated with darker skin,
C O N N E C T I O N CHAPTER 9
The evidence suggests that sexual
orientation is determined—at least
in part—by heredity (p. 385).
C O N N E C T I O N CHAPTER 12
Schizophrenia is a psychotic
disorder that affects about 1 out
of 100 persons (p. 537).

48 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
which affords some protection from the sun, and lighter skin frequently identifies peo-
ple from high latitudes, which receive less sun. While we commonly speak of “race” in
terms of these superficial characteristics, biologists tell us there are no physical charac-
teristics that divide people cleanly into distinct “racial” groups. We are all one species.
In reality, physical characteristics of the so-called “races” blend seamlessly one into
another. There is no physical characteristic that reliably distinguishes the brain of a
person of one geographic region, skin color, or ethnic origin from that of another. Inside
the skull are many physical differences—even some gender differences—but no race-
based differences. We should think of “race,” therefore, as a socially defined term rather
than a biological one. Alternatively, the concept of culture is a far better explanation for
most—perhaps all—of the group differences important to psychologists (Cohen, 1998).
Just because race is not a precise biological concept, however, doesn’t mean its
social meaning is unimportant. On the contrary, race as a socially defined category can
exert powerful influences on behavior. We will see, for example, that social conceptions
of race influence expectations and prejudices. Please keep this notion in mind when
we look at studies in which people who identify with different racial or ethnic groups
are compared, for example, on intelligence and academic achievement (Eberhardt &
Randall, 1997; Hirschfeld, 1996).
PSYCHOLOGY MATTERS
Choosing Your Children’s Genes
Scientists already have the ability to control and alter the genetics of animals, like
Dolly, the late and famous fatherless sheep, cloned from one of her mother’s cells in
1996. Since that time, a variety of animals from cats to cattle have been cloned, though
the success rate is just 1 to 2 percent of attempts (American Medical Association,
2010). But what about the prospects for genetic manipulation in people? Thanks to
scientists working on the Human Genome Project, we are getting a glimpse of the
genetic instructions that make us human. We now know the sequence of nucleotides
on all the human chromosomes (Pennisi, 2001).
Psychologists expect this information to teach us something about the genetic basis
for human differences in abilities, emotions, and resistance to stress (Kosslyn et al.,
2002). High on the list will be disorders that affect millions: cancer, heart disease, au-
tism, and depression. But not all the promise of human genetics lies in the future. We
can already sample fetal cells and search for certain genetic problems, such as Down
syndrome, Tay-Sachs disease, and sickle-cell anemia. And while many people support
genetic testing, others wonder if technology is advancing faster than our ability to
address the ethical issues it presents.
One such technique, known as pre-implantation genetic diagnosis (PGD), was
developed to help couples decrease the risk of passing on a serious genetic disorder to an
unborn child. By testing the fetus or embryo at a very early stage, reproductive scientists
can ensure a genetically healthy fetus. Since its introduction in 1990, however, use of PGD
has broadened. The United States and some other countries now allow use of PGD for sex
selection: Almost half the clinics that offer PGD also offer parents the option to choose
whether they will have a boy or a girl (Adams, 2010). Moreover, “savior siblings” are be-
ing engineered, so parents who have a child with a life-threatening disease (such as leuke-
mia) can birth a sibling with the right bone marrow to save the ill child (Marcotty, 2010).
And, most recently, a fertility clinic in Los Angeles announced its plans to offer genetic
selection for physical traits such as height, hair color, and skin color (Naik, 2009). (Inter-
estingly, the clinic retracted its offer after receiving a letter of objection from the Vatican.)
But what will be the price of this technology?
Undoubtedly, parents in this brave new genetic world will want their children to be
smart and good looking—but by what standards will intelligence and looks be judged?
And will everyone be able to place an order for their children’s genes—or only the very
wealthy? You can be certain the problems we face will be simultaneously biological,
psychological, political, and ethical (Patenaude et al., 2002).
C O N N E C T I O N CHAPTER 6
While intelligence is influenced by
heredity, the relative contributions
of nature and nurture are hotly
debated (p. 251).
Read about Choosing Your Own
Children’s Genes at MyPsychLab

How Does the Body Communicate Internally? 49
Already, psychologists provide guidance about how genetic knowledge can best be
applied (Bronheim, 2000), particularly in helping people assess genetic risks in connec-
tion with family planning. We invite you to grapple with these issues by answering the
following questions:
• If you could select three genetic traits for your children, which ones would you
select?
• If a biological child of yours had a life-threatening illness, would you attempt to
conceive a “savior sibling?” Why or why not? What circumstances or conditions
would affect your decision?
• If you knew you might carry a gene responsible for a serious medical or
behavioral disorder, would you want to be tested before having children?
And would it be fair for a prospective partner to require you to be tested
before conceiving children? Would it be fair for the state to make such a
requirement?
These questions, of course, have no “right” answers; but your answers will help you
define your stand on some of the most important issues we will face in this century. In
considering them, think about how the critical thinking guidelines from Chapter 1
might affect your responses. For instance, to what degree might your own emotional
bias color your reaction to these questions?
2.2 KEY QUESTION
How Does the Body Communicate Internally?
Imagine this: You are driving on a winding mountain road, and suddenly a car comes
directly at you. At the last instant, you and the other driver swerve in opposite direc-
tions. Your heart pounds—and keeps pounding for several minutes after the danger has
passed. Externally, you have avoided a potentially fatal accident. Internally, your body
has responded to two kinds of messages from its two communication systems.
One is the fast-acting nervous system, with its extensive network of nerve cells
carrying messages in pulses of electrical and chemical energy throughout the body.
Check Your Understanding
1. RECALL: Explain how natural selection increases certain genetic
characteristics within a population of organisms.
2. APPLICATION: Name one of your own characteristics that is part
of your phenotype.
3. RECALL: Which of the following statements expresses the correct
relationship?
a. Genes are made of chromosomes.
b. DNA is made of chromosomes.
c. Nucleotides are made of genes.
d. Genes are made of DNA.
4. ANALYSIS: In purely evolutionary terms, which would be a
measure of your success as an organism?
a. your intellectual accomplishments
b. the length of your life
c. the number of children you have
d. the contributions you make to the happiness of humanity
5. UNDERSTANDING THE CORE CONCEPT: Behavior
consistently found in a species is likely to have a genetic basis
that evolved because the behavior was adaptive. Name a common
human behavior that illustrates this concept.
Answers 1. Natural selection relies on genetic variation among individuals within a population (or group) of organisms. Those best adapted to the
environment have a survival and reproduction advantage, leaving more offspring than others. Over generations, these adaptive characteristics
increase within the population. 2. Your observable physical and behavioral characteristics, such as height and weight or the way you speak, make
up your phenotype. 3. d 4. c 5. Language, social interaction, self-preservation, basic parenting “instincts,” feeding in newborns—all have been
influenced by evolution.
Study and Review at MyPsychLab

50 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
This first-responder network comes quickly to your rescue in an emergency, carrying
orders that accelerate your heart and tense your muscles for action. The other com-
munication network, the slower-acting endocrine system, sends follow-up messages
that support and sustain the response initiated by the nervous system. To do this, the
endocrine glands, including the pituitary, thyroid, adrenals, and gonads, use chemical
messengers we call hormones.
The two internal message systems cooperate not only in stressful situations but
also in happier circumstances of high arousal, as when you receive an unexpected
“A” on a test or meet someone especially attractive. The endocrine system and ner-
vous system also work together during states of low arousal to keep vital body func-
tions operating smoothly. Managing this cooperation between the endocrine system
and the nervous system is the body’s chief executive, the brain—which brings us to
our Core Concept:
Core Concept 2.2
The brain coordinates the body’s two communications systems, the
nervous system and the endocrine system, which use similar chemi-
cal processes to communicate with targets throughout the body.
Why is this notion important for your understanding of psychology? For one thing,
these two communication systems are the biological bedrock for all our thoughts,
emotions, and behaviors. Another reason for studying the biology behind the
body’s internal communications is that it can help us understand how drugs, such
as caffeine, alcohol, ecstasy, and Prozac, can change the chemistry of the mind.
Finally, it will help you understand many common brain-based conditions, such as
stroke, multiple sclerosis, and depression.
Our overview of the body’s dual communication systems first spotlights the build-
ing block of the nervous system: the neuron. Next, we will see how networks of neu-
rons work together as modular components of the greater network of the nervous
system that extends throughout the body. Then we will shift our attention to the endo-
crine system, a group of glands that operates together and in parallel with the nervous
system—also throughout the body.
The Neuron: Building Block of the Nervous System
Like transistors in a computer, neurons or nerve cells are the fundamental process-
ing units in the brain. In simplest terms, a neuron is merely a cell specialized to
receive, process, and transmit information to other cells. And neurons do that very
efficiently: A typical nerve cell may receive messages from a thousand others and,
within a fraction of a second, decide to “fire,” passing the message along at speeds
up to 300 feet per second to another thousand neurons—or sometimes as many as
10,000 (Pinel, 2005).
Types of Neurons While neurons vary in shape and size, all have essentially the same
structure, and all send messages in essentially the same way. Nevertheless, biopsycholo-
gists distinguish three major classes of neurons according to their location and function:
sensory neurons, motor neurons, and interneurons (see Figure 2.2). Sensory neurons, or
afferent neurons, act like one-way streets that carry traffic from the sense organs toward
the brain. Accordingly, afferent neurons treat the brain to all your sensory experience,
including vision, hearing, taste, touch, smell, pain, and balance. For example, when you
test the water temperature in the shower with your hand, afferent neurons carry the
message toward the brain.
In contrast, motor neurons, or efferent neurons, form the one-way routes that
transport messages away from the brain and spinal cord to the muscles, organs, and
glands. Motor neurons, therefore, carry the instructions for all our actions. So, in
neuron Cell specialized to receive and transmit
information to other cells in the body—also called a
nerve cell. Bundles of many neurons are called nerves.
sensory neuron A nerve cell that carries mes-
sages toward the central nervous system from sense
receptors; also called afferent neurons.
motor neuron A nerve cell that carries messages
away from the central nervous system toward the
muscles and glands; also called efferent neurons.

How Does the Body Communicate Internally? 51
our shower example, the motor neurons deliver the message that tells your hand
just how much to move the shower control knob.
Sensory and motor neurons rarely communicate directly with each other, except in
the simplest of reflexive circuits. Instead, they usually rely on the go-between interneurons
(also shown in Figure 2.2), which make up most of the billions of cells in the brain and
spinal cord. Interneurons relay messages from sensory neurons to other interneurons
or to motor neurons, sometimes in complex pathways. In fact, the brain itself is largely
a network of intricately connected interneurons. To see how fast these neural circuits
work, try the demonstration in the accompanying Do It Yourself! box.
How Neurons Work A look at Figure 2.3 will help you visualize the neuron’s main
components. The “receiver” parts, which accept most incoming messages, consist of
finely branched fibers called dendrites. These dendritic fibers extend outward from the
cell body, where they act like a net, collecting messages received from other neurons or
by direct stimulation of the sense organs (e.g., the eyes, ears, or skin).
interneuron A nerve cell that relays messages
between nerve cells, especially in the brain and
spinal cord.
dendrite Branched fiber that extends outward from
the cell body and carries information into the neuron.
Sensory cortex
Pain message to brain
Spinal cord
Interneuron
Sensory neuron
Skin receptors
Muscle
Motor neuron
FIGURE 2.2
Sensory Neurons, Motor Neurons,
and Interneurons
Information about the water temperature
in the shower is carried by thousands
of sensory neurons (afferent neurons)
from the sense organs to the central
nervous system. In this case, the mes-
sage enters the spinal cord and is relayed
by interneurons to the brain. There, the
information is assessed and a response
is initiated (“Turn the water temperature
down!”). These instructions are sent to
the muscles by means of motor neurons
(efferent neurons). Large bundles of the
message-carrying fibers from these
neurons are called nerves.
NEURAL MESSAGES AND REACTION TIME
For only a dollar, you can find out how long
it takes for the brain to process information
and initiate a response.
Hold a crisp dollar bill by the middle
of the short side so that it dangles down-
ward. Have a friend put his or her thumb
and index fingers on opposite sides and
about an inch away from the center of
the bill. Instruct your friend to pinch the
thumb and fingers together, and attempt to
catch the bill when you drop it.
If you drop the bill without warning
(being careful not to signal your inten-
tions), your friend’s brain will not be able
to process the information rapidly enough
to get a response to the hand before the
dollar bill has dropped safely away.
What does this demonstrate? The time
it takes to respond reflects the time it takes
for the sensory nervous system to take in
the information, for the brain to process
it, and for the motor system to produce
a response. All this involves millions of
neurons; and, even though they respond
quickly, their responses do take time.
Simulate the Experiment
at MyPsychLab
Nerve
Impulse and Afferent and Efferent
Neurons

52 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
Dendrites then pass their messages on to the central part of the neuron, called the
cell body or soma. Not only does the soma house the cell’s chromosomes, it also con-
ducts on-the-spot evaluation of the hundreds (or sometimes thousands) of messages
received by the cell, often simultaneously. Making the assessment even more complex,
some of these messages received by the neuron are excitatory (saying, in effect, “Fire!”)
and some are inhibitory (“Don’t fire!”). The “decision” made by the soma depends
on its overall level of arousal—which depends, in turn, on the sum of the incoming
messages.
When excitation triumphs over inhibition, the neuron initiates a message of its
own and sends it along a single “transmitter” fiber known as the axon. These axons
vary tremendously in length. In a college basketball player, axons connecting the spinal
cord with the toes can be more than 3 feet long, while at the other extreme, axons of
interneurons in the brain may span only a tiny fraction of an inch.
The Action Potential When arousal in the cell body reaches a critical level, it triggers an
electrical impulse in the axon—like the electronic flash of a camera—and, as we said,
the cell “fires.” Much like a battery, the axon gets the electrical energy it needs to fire
from charged chemicals called ions. In its normal, resting state—appropriately called
the resting potential—the ions inside the axon have a negative electrical charge. But this
negative state is easily upset. When the cell body becomes excited, it triggers a cascade
of events, known as the action potential, that temporarily reverses the charge and causes
an electrical signal to race along the axon (see Figure 2.3).
soma The part of a cell (such as a neuron) contain-
ing the nucleus, which includes the chromosomes; also
called the cell body.
axon In a nerve cell, an extended fiber that con-
ducts information from the soma to the terminal but-
tons. Information travels along the axon in the form of
an electric charge called the action potential.
resting potential The electrical charge of the axon
in its inactive state, when the neuron is ready to “fire.”
action potential The nerve impulse caused by a
change in the electrical charge across the cell mem-
brane of the axon. When the neuron “fires,” this charge
travels down the axon and causes neurotransmitters to
be released by the terminal buttons.
Action
potential
(neural impluse)
Neurotransmitter
molecule
Axon
Vesicles
Presynaptic
membrane
Some neurotransmitters
do not “fit the lock”
Receptor
sitesSome neurotransmitters
“fit the lock”
Dendrite
Postsynaptic
membrane
Synaptic
cleft
Axon Soma
Dendrites
Nucleus
Cytoplasm
Myelin sheath
(covering the
axon)
Synapses
Terminal
buttons
FIGURE 2.3
Structure and Function of the Neuron
A typical neuron receives thousands of messages at a time through its dendrites and soma (cell body). When the soma becomes sufficiently
aroused, its own message is then passed to the axon, which transmits it by means of an action potential to the cell’s terminal buttons. There, tiny
vesicles containing neurotransmitters rupture and release their contents into the synapse (synaptic cleft). Appropriately shaped transmitter mol-
ecules arriving at the postsynaptic membrane can dock at receptors, where they stimulate the receiving cell. Excessive transmitters are taken back
into the “sending” neuron by means of reuptake.

How Does the Body Communicate Internally? 53
How does the electrical charge reverse itself? During the action potential, tiny pores
open in a small area of the axon’s membrane adjacent to the soma, allowing a rapid
influx of positive ions. Almost immediately, the internal charge in that part of the axon
changes from negative to positive. (We’re talking 1/1000 of a second here.) Then, like a
row of falling dominoes, these changes in the cell membrane progress down the axon.
The result is an electrical signal that races from the soma toward the axon ending.
There’s no halfway about this action potential: Either the axon “fires” or it doesn’t.
Neuroscientists call this the all-or-none principle. Incidentally, when this process careens
out of control, with very large numbers of neurons becoming hypersensitive and firing
too easily, the result can be an epileptic seizure.
Then, almost immediately after firing, the cell’s “ion pump” flushes out the posi-
tively charged ions and restores the neuron to its resting potential, ready to fire
again. Incredibly, the whole complex cycle may take less than a hundredth of a sec-
ond. It is an amazing performance—and that is not the end of the process. Informa-
tion carried by the action potential must still traverse a tiny gap before reaching
another cell.
Synaptic Transmission Despite their close proximity to each other, nerve cells do not
actually meet. A microscopic gap, called a synapse, lies between them, acting as an
electrical insulator (see Figure 2.3). This synaptic gap (or synaptic cleft) prevents the
charge from jumping directly from the axon to the next cell in the circuit (Dermietzel,
2006). Instead, the neuron must first stimulate tiny bulblike structures called terminal
buttons located at the ends of the axon. Then, in a remarkable sequence of events
known as synaptic transmission, the electrical message morphs into a chemical message
that flows across the synaptic cleft and on to the next neuron. Let’s examine that pro-
cess more closely.
Neurotransmitters When the electrical impulse arrives at the terminal buttons, tiny
bubblelike vesicles (sacs) inside them burst and release their chemical contents, known
as neurotransmitters, into the synapse. These neurotransmitters then attempt to ferry the
neural message across the gap to the next neuron in the chain (again, see Figure 2.3).
What do we mean by “attempt”? This is where the process gets a bit more complicated—
partly because there are dozens of different neurotransmitters, each of which has a dif-
ferent chemical structure, and partly because each ruptured vesicle releases about 5,000
neurotransmitter molecules into the synapse (Kandel & Squire, 2000)! So, in order for
the neural message to be passed along, there must be a receptor site on a nearby neuron
that is an exact match to the shape of one of the neurotransmitters. (Remember learning
in your basic science class what different molecules look like?) When there is a match,
the neurotransmitter fits into the receptor site, much as a key fits into a lock. This lock-
and-key process then stimulates the receiving neuron, which passes the message onward.
What happens to neurotransmitters that don’t find a matching receptor site?
Through a process called reuptake, many of them are drawn back into vesicles. Others
are broken down by specially matched enzymes, rather like a chemical cleanser that
removes unwanted substances from your clothing or carpet. Learning about these dual
processes has proven useful in research aimed at developing treatments for a variety
of disorders. For example, certain drugs—such as the well-known Prozac and its nu-
merous chemical cousins—interfere with the reuptake process for a neurotransmitter
called serotonin, which you may have heard is related to depression. By inhibiting the
reuptake process for serotonin, the chemical remains available in the synapse longer,
which increases the odds it will be picked up by a matching receptor site and utilized.
Other drugs, such as Aricept, used to treat Alzheimer’s disease, interfere with the work
of the cleanup enzyme for acetylcholine (another neurotransmitter), which has the
same result as reuptake inhibitors: It ultimately leaves more of the chemical available
for use (National Institute on Aging, 2010). Table 2.1 describes several neurotrans-
mitters found especially relevant to psychological functioning. We will also talk more
about neurotransmitters and their relation to drug action in the upcoming Psychology
Matters at the end of this section.
all-or-none principle Refers to the fact that the
action potential in the axon occurs either completely or
not at all.
synapse The microscopic gap that serves as a com-
munications link between neurons. Synapses also occur
between neurons and the muscles or glands they serve.
terminal buttons Tiny bulblike structures at the
end of the axon that contain neurotransmitters that
carry the neuron’s message into the synapse.
synaptic transmission The relaying of
information across the synapse by means of
chemical neurotransmitters.
neurotransmitter Chemical messenger that
relays neural messages across the synapse. Many
neurotransmitters are also hormones.
reuptake The process by which unused
neurotransmitters are drawn back into the vesicles
of their originating neuron
Explore the Concept The Action
Potential at MyPsychLab

54 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
Synchronous Firing Over the past decade, neuroscientists have discovered that some
neurons—a small minority—don’t play by the customary rules of synaptic transmis-
sion. That is, instead of using neurotransmitters to send messages across the synapse,
they forego the chemical messages and communicate directly through electrical con-
nections (Bullock et al., 2005; Dermietzel, 2006). Scientists have found these excep-
tional neurons with electrical synapses concentrated in special parts of the brain that
orchestrate synchronized activity in a large number of other neurons, such as those
TABLE 2.1 Seven Important Neurotransmitters
Neurotransmitter Normal Function
Problems Associated
with Imbalance
Substances
That Affect the
Action of This
Neurotransmitter
Dopamine A transmitter used
in brain circuits that
produces sensations
of pleasure and
reward
Used by CNS neurons
involved in voluntary
movement
Schizophrenia
Parkinson’s disease
Cocaine
Amphetamine
Methylphenidate
(Ritalin)
Alcohol
Serotonin Regulates sleep and
dreaming, mood, pain,
aggression, appetite,
and sexual behavior
Depression
Certain anxiety
disorders
Obsessive–compulsive
disorder
Fluoxetine (Prozac)
Hallucinogenics
(e.g., LSD)
Norepinephrine Used by neurons in
autonomic nervous
system and by
neurons in almost
every region of the
brain
Controls heart rate,
sleep, stress, sexual
responsiveness,
vigilance, and
appetite
High blood pressure
Depression
Tricyclic
antidepressants
Beta-blockers
Acetylcholine The primary
neurotransmitter used
by efferent neurons
carrying messages
from the CNS
Also involved in some
kinds of learning and
memory
Certain muscular
disorders
Alzheimer’s disease
Nicotine
Black widow spider
venom
Botulism toxin
Curare
Atropine
Barbiturates
GABA The most prevalent
inhibitory
neurotransmitter in
neurons of the CNS
Anxiety
Epilepsy
“Minor” tranquilizers
(e.g., Valium, Librium)
Alcohol
Glutamate The primary excitatory
neurotransmitter in
the CNS
Involved in learning
and memory
Release of excessive
glutamate apparently
causes brain damage
after stroke
PCP (“angel dust”)
Endorphins Pleasurable sensations
and control of pain
Lowered levels
resulting from opiate
addiction
Opiates: opium,
heroin, morphine,
methadone

How Does the Body Communicate Internally? 55
involved in the coordinated beating of the heart. These synchronized bursts may also
underlie the greatest mystery of all in the brain: how the brain combines input from
many different modules into a single sensation, idea, or action.
Plasticity Regardless of the communication method—electrical or chemical—neurons
have the ability to change. One of our most extraordinary capabilities, plasticity, al-
lows our brain to adapt or modify itself as the result of experience (Holloway, 2003;
Kandel & Squire, 2000). For example, when we learn something new, dendrites can
actually grow, and new synapses can be formed, both of which help create new con-
nections with different neurons. And although earlier research focused on the brain’s
plasticity in our early years of life, newer studies find plasticity in the adult brain as
well (Chklovskii et al., 2004).
Thus, plasticity helps account for the brain’s ability to compensate for injury, such
as when Jill Bolte Taylor’s massive stroke wiped out a significant portion of one side
of her brain, taking with it her language abilities, mathematical reasoning, and analyti-
cal skills. With the help of her mother and a team of rehabilitation experts, she slowly
re-learned those skills—thanks to her brain’s ability to create brand new connections
to compensate for what was lost. Plasticity, then, enables the brain to continually be
restructured and “reprogrammed,” both in function and in physical structure, by expe-
rience (LeDoux, 2002).
Plasticity accounts for much of our human ability to adapt to our experiences—for
better or for worse. For example, as a violin player gains expertise, the motor area of
the brain linked to the fingers of the left hand becomes larger (Juliano, 1998). Like-
wise, the brain dedicates more neural real estate to the index finger used by a blind
Braille reader (Elbert et al., 1995; LeDoux, 1996). On the other hand, plasticity also
allows traumatic experiences to alter the brain’s emotional responsiveness in ways that
can interfere with everyday functioning (Arnsten, 1998). Thus, brain cells of soldiers
who experience combat or of people who have been sexually assaulted can become
rewired to be more sensitive to cues that could, in a similar situation, help protect them
from harm. In everyday, nonthreatening circumstances, however, this same hair-trigger
responsiveness can cause them to overreact to mild stressors—or even to simple unex-
pected surprises.
Brain Implants Plasticity, of course, cannot compensate for injuries that are too
extensive. Driven by this problem, neuroscientists are experimenting with computer
chips implanted in the brain, hoping to restore some motor control in paralyzed pa-
tients. In one remarkable case, a 26-year-old paralyzed male received such a chip as
an implant in his motor cortex. By merely thinking about movement, he learned to
send signals from his brain to a computer, controlling a cursor by thought, much as he
might have used a computer’s mouse by hand. In this cerebral way, he could play video
games, draw circles, operate a TV set, and even move a robotic hand—all of which his
paralysis would have made impossible without the implant (Dunn, 2006; Hochberg
et al., 2006).
Glial Cells: A Support Group for Neurons Interwoven among the brain’s vast net-
work of neurons is an even greater number of glial cells, once thought to “glue” the
neurons together. (In fact, the name comes from the Greek word for “glue.”) Now,
however, we know that glial cells provide structural support for neurons and also help
form new synapses during learning (Fields, 2004; Gallo & Chittajallu, 2001). In addi-
tion, glial cells form the myelin sheath, a fatty insulation covering many axons in the
brain and spinal cord. Like the casing on an electrical cable, the myelin sheath on a
neuron insulates and protects the cell. It also helps speed the conduction of impulses
along the axon (refer to Figure 2.3). Certain diseases, such as multiple sclerosis (MS),
attack the myelin sheath, resulting in poor conduction of nerve impulses. That defi-
ciency accounts for the variety of symptoms faced by persons with MS, ranging from
difficulty with motor movement to sensory deficit to impairments in cognitive func-
tioning (National Institutes of Health, 2010).
plasticity The nervous system’s ability to adapt or
change as the result of experience. Plasticity may also
help the nervous system adapt to physical damage.
C O N N E C T I O N CHAPTER 14
Extremely traumatic
experiences can cause
posttraumatic stress disorder,
which can produce physical
changes in the brain (p. 605).
glial cell One of the cells that provide structural
support for neurons. Glial cells also provide an insulat-
ing covering (the myelin sheath) of the axon for some
neurons, which facilitates the electrical impulse.

56 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
So there you have the two main building blocks of the nervous system: neurons,
with their amazing plasticity, and the supportive glial cells, which protect the neurons
and help propagate neural messages. But, wondrous as these individual components
are, in the big picture of behavior and mental processes, a single cell doesn’t do very
much. It takes millions of neurons flashing their electrochemical signals in synchro-
nized waves back and forth through the incredibly complex neural networks in your
brain to produce thoughts, sensations, and feelings. Similarly, all your actions arise
from waves of nerve impulses delivered to your muscles, glands, and organs through
the nervous system. It is to this larger picture—the nervous system—that we now turn
our attention.
The Nervous System
If you could observe a neural message as it moves from stimulus to response, you
would see it flow seamlessly from one part of the nervous system to another. The signal
might begin, for example, in the eyes, then travel to the brain for extensive processing,
and finally reemerge from the brain as a message instructing the muscles to respond.
In fact, the nervous system, consisting of all the nerve cells in the body, functions as a
single, complex, and interconnected unit. Nevertheless, we find it convenient to dis-
tinguish among divisions of the nervous system based on their location and the type
of processing they do. The most basic distinction recognizes two major divisions: the
central nervous system and the peripheral nervous system (see Figure 2.4).
The Central Nervous System Composed of the brain and spinal cord, the central
nervous system (CNS) serves as the body’s “command central.” The brain, filling roughly
a third of the skull, makes complex decisions, coordinates our body functions, and
initiates most of our behaviors. The spinal cord, playing a supportive role, serves as
a sort of neural cable, connecting the brain with parts of the peripheral sensory and
motor systems.
Reflexes The spinal cord has another job too. It takes charge of simple, swift reflexes—
responses that do not require brain power, such as the reflex your physician elicits with
nervous system The entire network of neurons
in the body, including the central nervous system, the
peripheral nervous system, and their subdivisions.
central nervous system (CNS) The brain
and the spinal cord.
reflex Simple unlearned response triggered by
stimuli—such as the knee-jerk reflex set off by tapping
the tendon just below your kneecap.
Nervous system
Peripheral nervous system
Autonomic nervous system
(communicates with internal
organs and glands)
Somatic nervous system
(communicates with sense organs
and voluntary muscles)
Sympathetic
division
(arousing)
Parasympathetic
division
(calming)
Sensory (afferent)
nervous system
(sensory input)
Motor (efferent)
nervous system
(motor output)
Central nervous system
(brain and spinal cord)
FIGURE 2.4
Organization of the Nervous System
This figure shows the major divisions of the nervous system. The figure on the left shows the central nervous system, while the figure on the right
shows the peripheral nervous system.

How Does the Body Communicate Internally? 57
a tap on the knee. We know that the brain is not involved in these simple re-
flexes, because a person whose spinal cord has been severed doesn’t sense the
pain—but may still be able to withdraw a limb reflexively from a painful stim-
ulus. Voluntary movements, however, do require the brain. That’s why damage
to nerves in the spinal cord can produce paralysis of the limbs or trunk. The
extent of paralysis depends on the location of the damage: The higher the site
of damage, the greater the extent of the paralysis.
Contralateral Pathways Significantly, most sensory and motor pathways carry-
ing messages between the brain and the rest of the body are contralateral—that
is, they cross over to the opposite side in the spinal cord or the brain stem. The
result is that each side of the brain communicates primarily with the opposite
side of the body or the environment. This fact is important in understanding
how damage to one side of the brain often results in disabilities on the opposite
side of the body (see Figure 2.5). Jill Bolte Taylor’s stroke, for example, was in
the left side of her brain, but it was her right arm that became paralyzed during
the event.
The Peripheral Nervous System Also playing a supportive role, the peripheral nervous
system (PNS) connects the central nervous system with the rest of the body through
bundles of sensory and motor axons called nerves. The many branches of the PNS
carry messages between the brain and the sense organs, the internal organs, and the
muscles. In this role, the peripheral nervous system carries incoming messages telling
your brain about the sights, sounds, tastes, smells, and textures of the world. Likewise,
it carries outgoing signals telling your body’s muscles and glands how to respond.
You might think of the PNS as a pick-up-and-delivery service for the central ner-
vous system. If, for example, an aggressive dog approaches you, your PNS picks up
the auditory information (barking, growling, snarling) and visual information (bared
teeth, hair standing up on the neck) for delivery to the brain. Quickly, perceptual and
emotional circuits in the brain assess the situation (Danger!) and communicate with
other circuits, dispatching orders for a hasty retreat. The PNS then delivers those or-
ders to mobilize your heart, lungs, legs, and other body parts needed to respond to the
emergency. It does this through its two major divisions, the somatic nervous system
and the autonomic nervous system. One deals primarily with our external world, the
other with our internal responses. (A few moments spent studying Figure 2.4 will help
you understand these divisions and subdivisions.)
The Somatic Division of the PNS Think of the somatic nervous system as the brain’s com-
munications link with the outside world. Its sensory component connects the sense
organs to the brain, and its motor component links the CNS with the skeletal muscles
that control voluntary movements. So, for example, when you see a slice of pizza, the
visual image is carried to the brain by the somatic division’s afferent (sensory) system.
Then, if all goes well, the efferent (motor) system sends instructions to muscles that
propel the pizza on just the right trajectory into your open mouth.
The Autonomic Division of the PNS The other major division of the PNS takes over once
the pizza starts down your throat and into the province of the autonomic nervous system
(autonomic means self-regulating or independent). This network carries signals that
regulate our internal organs as they perform such jobs as digestion, respiration, heart
rate, and arousal. And it does so unconsciously—without our having to think about it.
The autonomic nervous system also works when you are asleep. Even during anesthe-
sia, autonomic activity sustains our most basic vital functions.
And—wouldn’t you know?—biopsychologists further divide the autonomic
nervous system into two subparts: the sympathetic and parasympathetic divisions
(as shown in Figure 2.6). The sympathetic division arouses the heart, lungs, and other
organs in stressful or emergency situations, when our responses must be quick and
powerfully energized. Often called the “fight-or-flight” system, the sympathetic
division carries messages that help us respond quickly to a threat either by attacking
contralateral pathways Sensory and motor
pathways between the brain and the rest of the body
cross over to the opposite side en route, so messages
from the right side of the body are processed by the left
side of the brain and vice versa.
peripheral nervous system (PNS) All parts
of the nervous system lying outside the central nervous
system. The peripheral nervous system includes the
autonomic and somatic nervous systems.
somatic nervous system A division of the
peripheral nervous system that carries sensory infor-
mation to the central nervous system and also sends
voluntary messages to the body’s skeletal muscles.
autonomic nervous system The portion of the
peripheral nervous system that sends communications
between the central nervous system and the internal
organs and glands.
sympathetic division The part of the auto-
nomic nervous system that sends messages to internal
organs and glands that help us respond to stressful
and emergency situations.
Right brain
hemisphere
Left brain
hemisphere
• Communicates
with left
side of
the body
• Receives
input from
the left
visual field
• Communicates
with right
side of the
body
• Receives input
from the right
visual field
FIGURE 2.5
Contralateral Connections
For most sensory and motor functions,
each side of the brain communicates with
the opposite side of the body. (This is
known as contralateral communication.)

58 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
or fleeing. The sympathetic system also creates the tension and arousal you feel during
an exciting movie or first date. Perhaps you can recall how the sympathetic division of
your autonomic nervous system made you feel during your last oral presentation. Was
it hard to breathe? Were your palms sweaty? Did your stomach feel queasy? All these
are sympathetic division functions.
The parasympathetic division does just the opposite: It applies the neural brakes,
returning the body to a calm and collected state. But even though it has an opposing
action, the parasympathetic division works cooperatively with the sympathetic system,
like two children on a teeter-totter. Figure 2.6 shows the most important connections
made by these two autonomic divisions.
Now, having completed our whirlwind tour of the nervous system, we return our
attention briefly to its partner in internal communication, the endocrine system.
The Endocrine System
Perhaps you never thought of the bloodstream as a carrier of information, along with
oxygen, nutrients, and wastes. Yet blood-borne information, in the form of hormones,
serves as the communication channel among the glands of the endocrine system, shown
in Figure 2.7. (Endocrine comes from the Greek endo for “within” and krinein for
“secrete.”)
parasympathetic division The part of the
autonomic nervous system that monitors the routine
operations of the internal organs and returns the body
to calmer functioning after arousal by the sympathetic
division.
endocrine system The hormone system—the
body’s chemical messenger system, including the
endocrine glands: pituitary, thyroid, parathyroid,
adrenals, pancreas, ovaries, and testes.
PARASYMPATHETICSYMPATHETIC
Constricts pupil
Inhibits tear
glands
Increases
salivation
Slows heart
Constricts bronchi
Increases
digestive
functions of
stomach
Increases
digestive
functions of
intestine
Contracts bladder
Spinal
cord
Chain of
sympathetic
ganglia
Inhibits bladder
constriction
Decreases
digestive
functions of
intestine
Secretes
adrenalin
Decreases
digestive
functions of
stomach
Dilates bronchi
Accelerates heart
Dilates pupil
Inhibits salivation
Increases sweating
Stimulates
tear glands
FIGURE 2.6
Divisions of the Autonomic Nervous System
The sympathetic nervous system (at left) regulates internal processes and behavior in stressful situations. On their way to and from the spinal cord,
sympathetic nerve fibers make connections with specialized neural clusters called ganglia. The parasympathetic nervous system (at right) regulates
day-to-day internal processes and behavior.

How Does the Body Communicate Internally? 59
Playing much the same role as neurotransmitters in the nervous system, hormones
carry messages that influence not only body functions but also behaviors and emotions
(Damasio, 2003; LeDoux, 2002). For example, hormones from the pituitary stimulate
body growth. Hormones from the ovaries and testes influence sexual development and
sexual responses. Hormones from the adrenals produce the arousal accompanying fear.
And hormones from the thyroid control metabolism (rate of energy use). Once secreted
into the blood by an endocrine gland, hormones circulate throughout the body until
delivered to their targets, which may include not only other endocrine glands but also
muscles and organs. Table 2.2 outlines the major endocrine glands and the body systems
they regulate.
How Does the Endocrine System Respond in a Crisis? Under normal (un-
aroused) conditions, the endocrine system works in parallel with the parasympathetic
nervous system to sustain our basic body processes. But in a crisis, it shifts into a dif-
ferent mode, in support of the sympathetic nervous system. So, when you encounter a
stressor or an emergency (such as the speeding car headed toward you), the hormone
epinephrine (sometimes called adrenalin) is released into the bloodstream, sustaining
the body’s “fight or flight” reaction. In this way, the endocrine system finishes what
your sympathetic nervous system started by keeping your heart pounding and your
muscles tense, ready for action.
Later in the text, we will see what happens when this stressful state gets out of control.
For example, people who have stressful jobs or unhappy relationships may develop a
chronically elevated level of stress hormones in their blood, keeping them in a prolonged
state of arousal. The price your mind and body pay for this extended arousal can be dear.
hormones Chemical messengers used by the en-
docrine system. Many hormones also serve as
neurotransmitters in the nervous system.
C O N N E C T I O N CHAPTER 14
Prolonged stress messages can
produce physical and mental
disorders by means of the general
adaptation syndrome (p. 615).
Hypothalamus
Pituitary gland
Thyroid and
Parathyroid
Adrenal
glands
Pancreas
Testes
(male)
Ovaries
(female)
FIGURE 2.7
Endocrine Glands
The pituitary gland is the “master gland”
regulating the endocrine glands, whose
locations are shown here. The pituitary
gland is itself under control of the hy-
pothalamus, an important structure that
regulates many basic functions of the
body.

60 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
What Controls the Endocrine System? At the base of your brain, a “master gland,”
called the pituitary gland, oversees all these endocrine responses (see Figure 2.7). It does
so by sending out hormone signals of its own through the blood to other endocrine
glands throughout the body. But the pituitary itself is really only a midlevel manager.
It takes orders, in turn, from the brain—in particular from a small region to which it is
attached: the hypothalamus, a brain component about which we will have more to say
in a moment.
For now, we want to emphasize the notion that the peripheral nervous system and
the endocrine system provide parallel means of communication, coordinated by their
link in the brain. Ultimately, the brain decides which messages will be sent through
both networks. We will next turn our attention to the master “nerve center” that makes
these decisions—the brain—right after exploring how the concepts we just covered can
explain the effects of psychoactive drugs.
PSYCHOLOGY MATTERS
How Psychoactive Drugs Affect the Nervous System
The mind-altering effects of marijuana, LSD, cocaine, methamphetamines, and
sedatives attract millions of users. Millions more jolt their brains awake with the
caffeine of their morning coffee, tea, or energy drink and the nicotine in an ac-
companying cigarette; at night they may attempt to reverse their arousal with the
depressant effects of alcohol and sleeping pills. How do these seductive substances
pituitary gland The “master gland” that
produces hormones influencing the secretions of all
other endocrine glands, as well as a hormone that
influences growth. The pituitary is attached to the
brain’s hypothalamus, from which it takes its orders.
TABLE 2.2 Hormonal Functions of Major Endocrine Glands
These Endocrine Glands . . . Produce Hormones That Regulate. . .
Anterior pituitary Ovaries and testes
Breast milk production
Metabolism
Reactions to stress
Posterior pituitary Conservation of water in the body
Breast milk secretion
Uterus contractions
Thyroid Metabolism
Physical growth and development
Parathyroid Calcium levels in the body
Pancreas Glucose (sugar) metabolism
Adrenal glands Fight-or-flight response
Metabolism
Sexual desire (especially in women)
Ovaries Development of female sexual characteristics
Production of ova (eggs)
Testes Development of male sexual characteristics
Sperm production
Sexual desire (in men)

How Does the Body Communicate Internally? 61
achieve their effects? The answer involves the ability of psychoactive drugs to en-
hance or inhibit natural chemical processes in our brains.
Agonists and Antagonists
The ecstasy and the agony of psychoactive drugs come mainly from their interactions with
neurotransmitters. Some impersonate neurotransmitters by mimicking their effects in the
brain. Other drugs act less directly by enhancing or dampening the effects of neurotrans-
mitters. Those that enhance or mimic neurotransmitters are called agonists. Nicotine, for
example, is an agonist because it acts like the neurotransmitter acetylcholine (refer to Table
2.1). This has the effect of “turning up the volume” in the acetylcholine pathways (the ace-
tylcholine-using bundles of nerve cells controlling the muscles and connecting certain parts
of the brain). Similarly, the well-known antidepressant Prozac (fluoxetine) acts as an agonist
in the brain’s serotonin pathways, where it makes more serotonin available (see Figure 2.8).
In contrast, antagonists are chemicals that dampen or inhibit the effects of
neurotransmitters. Some drugs used to treat schizophrenia are antagonists because
they interfere with the neurotransmitter dopamine—effectively “turning the volume
down” and thus reducing the stimulation contributing to symptoms of delusions and
hallucinations (Nairne, 2009). So-called beta blockers, often used to manage heart
conditions, act as antagonists against both epinephrine and norepinephrine, thereby
counteracting the effects of stress. In general, agonists facilitate and antagonists inhibit
messages in parts of the nervous system using that transmitter.
Why Side Effects?
What causes drugs’ unwanted side effects? The answer to that question involves an im-
portant principle about the brain’s design. The brain contains many bundles of neurons—
neural pathways—that interconnect its components, much as rail lines connect major
cities. Moreover, each pathway employs only certain neurotransmitters—like rail lines
allowing only certain companies to use their tracks. This fact allows a drug affecting a
particular transmitter to target specific parts of the brain. Unfortunately for the drug
takers, different pathways may employ the same neurotransmitter for widely different
functions. Thus, the brain’s multiple serotonin pathways connect with brain structures
that affect not only mood but also sleep, appetite, and cognition, much as a railroad
has lines that connect with different many cities. Because of these multiple serotonin
pathways, taking Prozac (or one of its chemical cousins with other brand names) may
treat depression but, at the same time, affect sleep patterns, appetite, and thinking.
In fact, no psychoactive drug exists that acts like a “magic bullet,” only striking one
precise target in the brain without causing collateral effects.
agonists Drugs or other chemicals that enhance or
mimic the effects of neurotransmitters.
antagonists Drugs or other chemicals that inhibit
the effects of neurotransmitters.
neural pathways Bundles of nerve cells that
follow generally the same route and employ the same
neurotransmitter.
Cerebellum
Hypothalamus
Hippocampus
Projection to
spinal cord
Cerebral cortex
Serotonin pathways
(dark brown)
Thalamus
FIGURE 2.8
Serotonin Pathways in the Brain
Each neurotransmitter is associated with
certain neural pathways in the brain. In
this cross-section of the brain, you see
the main pathways for serotonin. Drugs
that stimulate or inhibit serotonin will
selectively affect the brain regions shown
in this diagram.

62 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
2.3 KEY QUESTION
How Does the Brain Produce Behavior
and Mental Processes?
In September 1848, a 25-year-old American railroad worker named Phineas Gage
sustained a serious head injury when a charge of blasting powder drove an iron rod
into his face, up through the front of his brain, and out through the top of his
head. (See accompanying photo.) Amazingly, Gage recovered from this injury and
lived another 12 years—but as a psychologically changed man (Fleischman, 2002;
Macmillan, 2000). Those who knew him remarked that Gage, once a dependable
and likeable crew boss, had become an irresponsible and rowdy ruffian. “Gage
was no longer Gage,” remarked his former companions (Damasio, 1994, p. 8). We
cannot help but wonder: Had the site of his injury—the front of his brain—been
the home of Phineas Gage’s “old self”? Further, the story of Gage’s transformation
sounds rather similar to Jill Bolte Taylor’s assertion that, since her stroke, she is no
longer “the same person.” What could explain these changes?
These stories raise a larger question: What is the connection between mind
and body? Humans have, of course, long recognized the existence of such a link—
although they didn’t always know the brain to be the organ of the mind. Even
today we might speak, as they did in Shakespeare’s time, of “giving one’s heart” to
another or of “not having the stomach” for something when describing revulsion—
even though we now know that love doesn’t really flow from the heart, nor disgust
from the digestive system, but that all emotions, desires, and thoughts originate in the
brain. (Apparently, this news hasn’t reached songwriters, who have yet to pen a lyric
proclaiming, “I love you with all of my brain.”)
At last, neuroscientists have begun unraveling the deep mysteries of this complex
organ of the mind. We now see the brain as a collection of distinct modules that work
together like the components of a computer. This new understanding of the brain
becomes the Core Concept for this final section of the chapter:
Core Concept 2.3
The brain is composed of many specialized modules that work
together to create mind and behavior.
Answers 1. nervous system/endocrine system 2. sympathetic/parasympathetic 3. When the electrical impulse arrives at the axon ending,
neurotransmitters are released into the synapse. Some lodge in receptor sites on the opposite side of the synapse, where they stimulate the receiving
neuron. 4. The pituitary gland 5. Your diagram should be similar to the one on the left side in Figure 2.3. The burst of electric energy (the action
potential) occurs in the axon. 6. neurotransmitters/hormones.
Check Your Understanding
1. RECALL: Of the body’s two main communication systems, the
is faster, while the sends longer-lasting
messages.
2. APPLICATION: You are touring a haunted house at Halloween,
when suddenly you hear a blood-curdling scream right behind you.
The division of your autonomic nervous system quickly
increases your heart rate. As you recover, the division
slows your heart rate to normal.
3. RECALL: Explain how a neural message is carried across the
synapse.
4. RECALL: Which gland takes orders from the brain but exerts
control over the rest of the endocrine system?
5. RECALL: Make a sketch of two connecting neurons, indicating
the locations of the dendrites, soma, axon, myelin sheath, terminal
buttons, and synapse. Which part of the neuron sends messages by
means of a brief electric charge?
6. UNDERSTANDING THE CORE CONCEPT: The chemical
messengers in the brain are called , while in the
endocrine system they are called .
Author Phil Zimbardo with the skull of
Phineas Gage.
Study and Review at MyPsychLab

How Does the Brain Produce Behavior and Mental Processes? 63
As you study the brain, you will find that each of its modular components has its
own responsibilities (Cohen & Tong, 2001). Some process sensations, such as vision
and hearing. Some regulate our emotional lives. Some contribute to memory. Some
generate speech and other behaviors. What’s the point? The specialized parts of the
brain act like members of a championship team: each doing a particular job yet work-
ing smoothly together. Happily, many of these modules perform their tasks automati-
cally and without conscious direction—as when you simultaneously walk, digest your
breakfast, breathe, and carry on a conversation. But, when something goes awry with
one or more of the brain’s components, as it does in a stroke or as happened to Phineas
Gage, the biological basis of thought or behavior comes to the fore.
Let’s begin the story of the brain by exploring how neuroscientists go about open-
ing the windows on its inner workings.
Windows on the Brain
Isolated within the protective skull, the brain can never actually touch velvet, taste
chocolate, have sex, or see the blue of the sky. It only knows the outside world second-
hand, through changing patterns of electrochemical activity in the peripheral nervous
system, the brain’s link with the world outside. To communicate within the body, the
brain must rely on the neural and endocrine pathways that carry its messages to and
from the muscles, organs, and glands throughout the body.
But what would you see if you could peer beneath the bony skull and behold the
brain? Its wrinkled surface, rather like a giant walnut, tells us little about the brain’s
internal structure or function. For that, technology—such as EEG, electrical stimula-
tion, and various types of brain scans—has opened new windows on the brain.
Sensing Brain Waves with the EEG For nearly one hundred years, neuroscientists
have used the electroencephalograph (or EEG) to record weak voltage patterns called
brain waves, sensed by electrodes pasted on the scalp. Much as city lights indicate
which parts of town are most “alive” at night, the EEG senses which parts of the brain
are most active. The EEG can identify, for example, regions involved in moving the
hand or processing a visual image. It can also reveal abnormal waves caused by brain
malfunctions, such as epilepsy (a seizure disorder that arises from an electrical “storm”
in the brain). You can see the sort of information provided by the EEG in Figure 2.9A.
Useful as it is, however, the EEG is not very precise, indiscriminately recording the
brain’s electrical activity in a large region near the electrode. Because there may be
electroencephalograph (EEG) A device for
recording brain waves, typically by electrodes placed on
the scalp. The record produced is known as an electro-
encephalogram (also called an EEG).
C O N N E C T I O N CHAPTER 8
Sleep researchers use brain waves,
recorded by the EEG, to identify
REM sleep, which is characterized
by dreaming (p. 335).
(A)
(B)
(D)(C) (E)
FIGURE 2.9
Windows on the Mind
Images from brain-scanning devices. (A) EEG; (B) CT scan; (C) PET; (D) MRI; and (E) fMRI. Each scanning and recording device has strengths
and weaknesses.

64 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
fewer than a dozen electrodes used, the EEG does not paint a detailed electrical picture
of the brain. Rather, it produces a coarse, moment-to-moment summary of electrical
activity in millions of neurons—making it all the more amazing that we can sometimes
read the traces of mental processes in an EEG record.
Mapping the Brain with Electric Probes The next step forward in understanding
the brain came about half a century ago, when the great Canadian neurologist Wilder
Penfield opened another window on the brain by “mapping” its pinkish-gray surface.
During brain surgery, using a pen-shaped electric probe, Penfield stimulated patients’
exposed brains with a gentle electric current and recorded the responses. (His patients
were kept awake, but under local anesthesia, so they felt no pain.)
This was not just an experiment born out of curiosity. As a surgeon, Penfield needed to
identify the exact boundaries of diseased brain areas to avoid removing healthy tissue. In
the process, he found the brain’s surface had distinct regions with distinct functions. Stimu-
lating a certain spot might cause the left hand to move; another site might produce a sensa-
tion, such as a flash of light. Stimulating still other sites occasionally provoked a memory
from childhood (Penfield, 1959; Penfield & Baldwin, 1952). Later, other scientists followed
his lead and probed structures deeper in the brain. There they found that electrical stimu-
lation could set off elaborate sequences of behavior or emotions. The overall conclusion
from such work is unmistakable: Each region of the brain has its own specific functions.
Computerized Brain Scans During the past few decades, increasingly detailed
views of the brain have emerged through sophisticated procedures collectively known
as brain scans. Some types of scans make images with X-rays, others use radioactive
tracers, and still others use magnetic fields. As a result, scientists can now make vivid
pictures of brain structures without opening the skull. In medicine, brain scans help
neurosurgeons locate brain abnormalities such as tumors or stroke-related damage.
And in psychology, images obtained from brain scans can reveal where our thoughts
and feelings are processed. How? Depending on the scanning method used, specific
regions of the brain may “light up” when, for example, a person reads, speaks, solves
problems, or feels certain emotions (Raichle, 1994).
The most common brain-scanning methods currently employed are CT, PET, MRI,
and fMRI:
CT scanning, or computerized tomography, creates digital images of the brain from
X-rays passed through the brain at various angles, as though it were being sliced like a
tomato. By means of sophisticated computer analysis, this form of tomography (from
the Greek tomos, “section”) reveals soft-tissue structures of the brain that X-rays alone
cannot show (see Figure 2.9B). CT scans produce good three-dimensional images and
are relatively inexpensive; the downside is they employ X-rays, which can be harmful in
high doses. CT scans are often used in hospitals for assessing traumatic brain injuries.
PET scanning, or positron emission tomography, shows brain activity (rather than just brain
structure). One common PET technique does this by sensing low-level radioactive glucose
(sugar), which concentrates in the brain’s most active circuits. Areas of high metabolic ac-
tivity show up brightly colored on the image (see Figure 2.9C). Thus, researchers can use
PET scans to show which parts are more active or less active during a particular task.
MRI, or magnetic resonance imaging, uses brief, powerful pulses of magnetic energy to
create highly detailed pictures of the structure of the brain (see Figure 2.9D). The MRI
technique makes exceptionally clear, three-dimensional images, without the use of
X-rays, which favors its use in research despite its higher cost.
fMRI, or functional magnetic resonance imaging, is a newer technique that records both
brain activity and structure, thus offering the advantages of both PET and MRI (Alper,
1993; Collins, 2001). By monitoring the blood and oxygen flow in the brain, it distin-
guishes more active brain cells from less active ones. Thus, fMRI lets neuroscientists
determine which parts of the brain are at work during various mental activities, much
the same as PET, only with the more detailed images of MRI (see Figure 2.9E).
Which Scanning Method Is Best? Each type of brain scan has its particular
strengths and weaknesses. For example, both PET and fMRI show which parts of the
CT scanning, or computerized
tomography A computerized imaging technique
that uses X-rays passed through the brain at various
angles and then combined into an image.
PET scanning, or positron emission
tomography An imaging technique that relies on
the detection of radioactive sugar consumed by active
brain cells.
MRI, or magnetic resonance imaging An
imaging technique that relies on cells’ responses in a
high-intensity magnetic field.
fMRI, or functional magnetic resonance
imaging A newer form of magnetic resonance
imaging that records both brain structure and brain
activity.

How Does the Brain Produce Behavior and Mental Processes? 65
brain are active during a particular task, such as talking, looking at a picture, or solv-
ing a problem. Standard MRI excels at distinguishing the fine details of brain structure.
But none of these methods can detect processes that occur only briefly, such as a shift
in attention or a startle response. To capture such short-lived “conversations” among
brain cells requires the EEG—which, unfortunately, is limited in its detail (Raichle,
1994). Currently, no single scanning technique gives biopsychologists a perfectly clear
“window” on all the brain’s activity.
Three Layers of the Brain
What we see through these windows also depends on the brain we are examining.
Birds and reptiles manage to make a living with a brain that consists of little more than
a stalk that regulates the most basic life processes and instinctual responses. Our own
more complex brains arise from essentially the same stalk, called the brain stem. From
an evolutionary perspective, then, this is the part of the brain with the longest ancestry
and most basic functions. On top of that stalk, we and our mammalian cousins have
evolved two more layers, known as the limbic system and the cerebrum, that give us
greatly expanded brain powers (see Figure 2.10).
brain stem The most primitive of the brain’s three
major layers. It includes the medulla, pons, and the
reticular formation.
Limbic system:
regulates emotions
and motivated
behavior
Cerebrum:
the thick, outer
layer of the brain,
divided into two
hemispheres Hypothalamus:
manages the body’s
internal state
Cerebral cortex:
(outer layer of cerebrum)
involved in complex
mental processes
Pons:
involved in regulation
of sleep
Reticular formation:
controls alertness
Hippocampus:
involved in
memory
Amygdala:
involved in emotion
and memory
Pituitary gland:
regulates glands
all over body
Thalamus:
relays sensory
information
Spinal cord:
pathway for neural
fibers traveling to
and from brain
Cerebellum:
regulates
coordinated
movement Brain stem:
sets brain’s general
alertness level and
warning system Medulla:
regulates autonomic
body functions such
as breathing and heart
rate.
FIGURE 2.10
Major Structures of the Brain
From an evolutionary perspective, the brain stem and cerebellum represent the oldest part of the brain; the limbic system
evolved next; and the cerebral cortex is the most recent achievement in brain evolution.

66 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
The Brain Stem and Its Neighbors If you have ever fought to stay awake in class,
you have struggled with your brain stem. Most of the time, however, it does its life-
sustaining jobs less obviously and less obnoxiously. We can infer one of the brain
stem’s tasks from its location, linking the spinal cord with the rest of the brain. In this
position, it serves as a conduit for nerve pathways carrying messages up and down the
spinal corridor between the body and the brain. This is also where many sensory and
motor pathways between the brain and our sense organs and skeletal muscles cross
over to the opposite side, thus connecting each side of the brain to the opposite side of
the body.
More than just a conduit, the brain stem also links together several important
information-processing regions, three of which are contained in the brain stem itself
(the medulla, the pons, and the reticular formation) and two that are adjacent (the
thalamus and the cerebellum) (Pinel, 2005). From an evolutionary standpoint, all these
are ancient structures found in the brains of creatures as diverse as penguins, pandas,
pythons, porcupines, and people. You can see their specific locations in Figure 2.10.
The medulla, appearing as a bulge in the brain stem, regulates basic body functions,
which include breathing, blood pressure, and heart rate. It operates on “automatic
pilot”—without conscious awareness—to keep our internal organs operating. An even
bigger bulge called the pons (meaning bridge) appears just above the medulla, where it
houses nerve circuits that regulate the sleep and dreaming cycle. True to its name, the
pons also acts as a “bridge” that connects the brain stem to the cerebellum, a structure
involved in making coordinated movements.
The reticular formation, running through the center of everything, is a pencil-shaped
bundle of nerve cells that forms the brain stem’s core. One of the reticular formation’s
jobs is keeping the brain awake and alert. Others include monitoring the incoming
stream of sensory information and directing attention to novel or important messages.
And—don’t blame your professor—it is the reticular formation you struggle with when
you become drowsy in class.
The thalamus, a pair of football-shaped bodies perched atop the brain stem, receives
nerve fibers from the reticular formation. Technically part of the cerebral hemispheres,
not the brain stem, the thalamus acts like the central processing chip in a computer,
directing the brain’s incoming and outgoing sensory and motor traffic. Accordingly, it
receives information from all the senses (except smell) and distributes this information
to appropriate processing circuits throughout the brain.
The cerebellum, tucked under the back of the cerebral hemispheres and behind the
brain stem, looks very much like a mini-brain—in fact, its name comes from the Latin
for “little brain.” Although not counted as part of the brain stem by many anatomists,
the cerebellum enables our motor coordination and balance (Spencer et al., 2003;
Wickelgren, 1998b). It is your cerebellum that allows you to run down a flight of stairs
without being conscious of the precise movements of your feet. The cerebellum also
helps us keep a series of events in order, as we do when listening to the sequence of
notes in a melody (Bower & Parsons, 2003). Finally, the cerebellum gets involved in a
basic form of learning that involves habitual responses we perform on cue—as when
you learn to wince at the sound of the dentist’s drill (Hazeltine & Ivry, 2002).
Taken together, these modules associated with the brain stem control the most
basic functions of movement and of life itself. Note, again, that much of their work is
automatic, functioning largely outside our awareness. The next two layers, however,
assert themselves more obviously in consciousness.
The Limbic System: Emotions, Memories, and More We’re sorry to report that
your pet canary or goldfish doesn’t have the emotional equipment that we mammals
possess. You see, only mammals have a fully developed limbic system, a diverse col-
lection of structures that wraps around the thalamus deep inside the cerebral hemi-
spheres (see Figure 2.11). Together, these ram’s-horn-shaped structures give us greatly
enhanced capacity for emotions and memory, faculties that offer the huge advantage
of mental flexibility. Because we have limbic systems, we don’t have to rely solely on
instincts and reflexes that dominate the behavior of simpler creatures.
medulla A brain-stem structure that controls breath-
ing and heart rate. The sensory and motor pathways
connecting the brain to the body cross in the medulla.
pons A brain-stem structure that regulates brain
activity during sleep and dreaming. The name pons
derives from the Latin word for “bridge.”
reticular formation A pencil-shaped structure
forming the core of the brain stem. The reticular for-
mation arouses the cortex to keep the brain alert and
attentive to new stimulation.
thalamus The brain’s central “relay station,” situ-
ated just atop the brain stem. Nearly all the messages
going into or out of the brain pass through the thalamus.
C O N N E C T I O N CHAPTER 3
The sense of smell has a unique
ability to evoke memories (p. 106).
cerebellum The “little brain” attached to the
brain stem. The cerebellum is responsible for coordi-
nated movements.
limbic system The middle layer of the brain,
involved in emotion and memory. The limbic system
includes the hippocampus, amygdala, hypothalamus,
and other structures.

How Does the Brain Produce Behavior and Mental Processes? 67
The limbic system houses other modules as well, regulating such important pro-
cesses as hunger, thirst, and body temperature. Overall, the limbic system is the brain’s
command post for emotions, motives, memory, and maintenance of a balanced condi-
tion within the body. Let’s examine each of its modules and their corresponding func-
tions in detail.
The Hippocampus and Memory The hippocampus enables our memory system. (Actually,
the brain has one hippocampus on each side, giving us two hippocampi [see Figure
2.10]). One of its jobs is to help us remember the location of objects, such as where
you left your car in a large parking lot (Squire, 2007). And it appears to actually grow
with experience, as suggested by a study of London cab drivers that found them to
have larger hippocampi than people who didn’t drive taxis, with more experienced
cabbies having the largest hippocampi of all (Maguire et al., 2003).
In addition to its role in spatial memory, the hippocampus plays a key role in mem-
ory storage, as evidenced by the tragic story of H. M. (referred to by his initials to pro-
tect his privacy). In 1953, when he was in his early 20s, H. M. underwent a radical and
experimental brain operation intended to treat frequent seizures that threatened his life
(Hilts, 1995). The surgery removed most of the hippocampus on both sides of his brain
and succeeded in reducing the frequency of his seizures. Unfortunately, the surgery also
produced an unforeseen and disastrous side effect: After the operation, new experi-
ences disappeared from H. M.’s memory almost as soon as they occurred, although his
memory for details of his life prior to the surgery remained intact. For the rest of his
life, when he tried to remember the years since 1953, H. M. drew a blank and was even
unable to recognize his daily caregivers. In fact, he continued to believe he was living
in 1953 right up until his death in 2008. This story, along with corroborating research,
indicates that—although the hippocampus is not the storage location for memory—it
is critically involved in creating new memories as we experience life.
hippocampus A component of the limbic system,
involved in establishing long-term memories.
Hunger and eating:
Hypothalamus
Fear and apprehension:
Amygdala
Learning and memory:
Hippocampus
FIGURE 2.11
The Limbic System
The structures of the limbic system are involved with motivation, emotion, and certain memory processes.

68 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
corpus callosum The band of nerve cells con-
necting and enabling communication between the two
cerebral hemispheres.
The Amygdala and Emotion Another limbic structure, the amygdala, takes its name from
its shape: amygdala means “almond” in Greek. Like many other brain structures, there
are actually two amygdalas, one extending in front of the hippocampus on each side
(see Figure 2.10).
In a classic experiment designed to find out what the amygdala does, Heinrich
Klüver and Paul Bucy (1939) surgically snipped the connections to the amygdala on
both sides of the brain in normally foul-tempered rhesus monkeys. Postsurgically, the
beasts became so docile and easy to handle that even Klüver and Bucy were surprised,
demonstrating the amygdala’s role in fear and aggression. More recent studies also
note that the amygdala—perhaps aided by its close proximity to the hippocampus—
uses memories to aid in emotional responses (Roozendaal et al., 2009), as when a per-
son who was previously in a serious car accident overreacts to a minor threat (such as
brief tailgating) from another driver. And this tiny structure has been found to activate
in both men and women (although to a greater degree in men) when they view sexually
arousing images (Hamann, 2005), illustrating its role in positive emotions as well as
negative ones.
Pleasure and the Limbic System In addition to the amygdala and hippocampus, the
limbic system contains several so-called pleasure centers that create good feelings when
aroused by electrical stimulation or by addictive drugs like cocaine, methamphetamine,
and heroin (Olds & Fobes, 1981; Pinel, 2005). But you don’t have to take drugs to
stimulate these limbic pleasure circuits. Sex will do it too. So will eating, drinking, or
exciting activities, such as riding a roller coaster. Even rich chocolate can arouse these
rewarding brain circuits (Small et al., 2001).
Reward circuits also participate in our response to humor. For most people, having
a brain scan is not a pleasant experience—largely because of the cramped spaces and
strange, loud noises made by the machine. But by telling jokes during the fMRI scan,
researchers got a few laughs from volunteers with their heads in the scanner. And,
sure enough, for those who thought the jokes were funny, parts of the brain’s reward
circuitry “lit up” (Goel & Dolan, 2001; Watson et al., 2007).
The Hypothalamus and Control over Motivation In passing, we have already met the
hypothalamus, the limbic structure responsible for maintaining the body in a stable, bal-
anced condition, partly by initiating endocrine system messages (refer to Figure 2.10).
Rich with blood vessels as well as neurons, the hypothalamus serves as your brain’s
blood-analysis laboratory. By constantly monitoring the blood, it detects small changes
in body temperature, fluid levels, and nutrients. When it detects an imbalance (too
much or too little water, for example), the hypothalamus immediately responds with
orders aimed at restoring balance.
The hypothalamus makes its influence felt in other ways as well. Although much
of its work occurs outside of consciousness, the hypothalamus sends neural messages
to “higher” processing areas in the brain, making us aware of its needs (hunger, for
example). It also controls our internal organs through its influence on the pituitary
gland, attached to the underside of the hypothalamus at the base of the brain. Thus,
the hypothalamus serves as the link between the nervous system and the endocrine
system, through which it regulates emotional arousal and stress. Finally, the hypothala-
mus plays a role in our emotions by hosting some of the brain’s reward circuits, espe-
cially those that generate the feel-good emotions associated with gratifying the hunger,
thirst, and sex drives.
The Cerebral Cortex: The Brain’s Thinking Cap When you look at a whole human
brain, you mostly see the bulging cerebral hemispheres—a little bigger than your two
fists held together. You may also notice they are connected by a band of fibers, known
as the corpus callosum, through which the two hemispheres communicate with each
other. The nearly symmetrical hemispheres form a thick cap (known as the cerebrum)
that accounts for two-thirds of the brain’s total mass and protects most of the limbic
amygdala A limbic system structure involved in
memory and emotion, particularly fear and aggression.
Pronounced a-MIG-da-la.
hypothalamus A limbic structure that serves as
the brain’s blood-testing laboratory, constantly moni-
toring the blood to determine the condition of the body.
C O N N E C T I O N CHAPTER 9
The hypothalamus contains
important control circuits for
several basic motives and drives,
such as hunger and thirst (p. 377).
cerebral hemispheres The large symmetrical
halves of the brain located atop the brain stem.

How Does the Brain Produce Behavior and Mental Processes? 69
system. The hemispheres’ thin outer layer, the cerebral cortex, with its distinctive folded
and wrinkled surface, allows billions of cells to squeeze into the tight quarters inside
your skull. Flattened out, the cortical surface would cover an area roughly the size of a
newspaper page. But because of its convoluted surface, only about a third of the cortex
is visible when the brain is exposed. For what it’s worth: Women’s brains have more
folding and wrinkling than do men’s, while, as we have seen, men’s brains are slightly
larger than women’s, on the average (Luders et al., 2004). And what does this cerebral
cortex do? The locus of our most awesome mental powers, it processes all our sensa-
tions, stores memories, and makes decisions—among many other functions, which we
will consider in our discussion of its lobes in the following text.
Although we humans take pride in our big brains, it turns out ours are not the biggest
on the planet. All large animals have large brains—a fact more closely related to body
size than to intelligence. Nor is the wrinkled cortex a distinctively human trait. Again, all
large animals have highly convoluted cortexes. If this bothers your self-esteem, take com-
fort in the fact that we do have more massive cortexes for our body weight than do other
big-brained creatures. Although no one is sure exactly how or why the brain became so
large in our species (Buss, 2008; Pennisi, 2006), comparisons with other animals show
that human uniqueness lies more in the way our brains function than in size.
Lobes of the Cerebral Cortex
In the late 1700s, the famous Austrian physician Franz Joseph Gall threw his considerable
scientific weight behind the idea that specific regions of the brain control specific mental
faculties, such as hearing, speech, movement, vision, and memory. Unfortunately, he car-
ried this sensible idea to extremes: In his theory of phrenology, Gall claimed that the brain
also had regions devoted to such traits as spirituality, hope, benevolence, friendship, de-
structiveness, and cautiousness. Moreover, he asserted that these traits could be detected
as bumps on the skull, the “reading” of which became a minor scam industry.
Gall’s ideas captured the public’s attention and became enormously popular, even
though his theory was mostly wrong. But he was absolutely right on one important
point: his doctrine of localization of function, the notion that different parts of the
brain perform different tasks. Discoveries in modern neuroscience have helped us cor-
rect Gall’s picture of the cerebral cortex. As we discuss the geography of the cortex,
please keep in mind that, while the lobes are convenient features, the functions we will
ascribe to each do not always respect their precise boundaries.
The Frontal Lobes Your choice of major, your plans for the summer, and your ability
to juggle your classes, your job, and your personal life all depend heavily on the corti-
cal regions at the front of your brain, aptly named the frontal lobes (you have one in
each hemisphere) (see Figure 2.12). Here, especially in the foremost region, known as
the prefrontal cortex, we find circuitry for our most advanced mental functions, such
as decision making, goal setting and follow-through, and anticipating future events
(Miller, 2006a). The biological underpinnings of personality, temperament, and our
sense of “self” seem to have important components here, too, as the case of Phineas
Gage first suggested (Bower, 2006c).
At the back of the frontal lobe lies a special strip of cortex capable of taking action
on our thoughts. Known as the motor cortex, this patch of brain takes its name from its
main function: controlling the body’s motor movement by sending messages to motor
nerves and on to voluntary muscles. As you can see in Figure 2.13, the motor cortex
contains an upside-down map of the body, represented by the homunculus (the dis-
torted “little man” in the figure). A closer look at the motor homunculus shows that it
exaggerates certain parts of the body, indicating that the brain allots a larger amount
of cortex to body parts requiring more fine-tuned motor control such as the lips,
tongue, and hands. Perhaps the most exaggerated areas represent the fingers (especially
the thumb), reflecting the importance of manipulating objects. Another large area con-
nects to facial muscles, used in expressions of emotion. Please remember, however, that
cerebral cortex The thin gray matter covering
the cerebral hemispheres, consisting of a ¼-inch layer
dense with cell bodies of neurons. The cerebral cortex
carries on the major portion of our “higher” mental
processing, including thinking and perceiving.
frontal lobes Cortical regions at the front of the
brain that are especially involved in movement and in
thinking.
motor cortex A narrow vertical strip of cortex in
the frontal lobes lying just in front of the central
fissure; controls voluntary movement.
The cerebral hemispheres of the human
brain.

70 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
commands from the motor cortex on one side of the brain control muscles on the op-
posite side of the body. So a wink of your left eye originates in your right motor cortex,
while the left motor cortex can wink your right eye.
Mirror Neurons Discovered in the Frontal Lobes Recently, neuroscientists discovered
a new class of neurons, called mirror neurons, scattered throughout the brain but
especially in motor areas of the frontal lobes. These mirror neurons appear to fire when
we observe another person performing some action, such as waving, drinking from a
cup, or wincing in pain—just as if we had performed the same act ourselves. In effect,
we may do and feel what we see in others—but in the privacy of our own minds
(Dobbs, 2006a).
What could be their purpose? For one thing, mirror neurons may help children
mimic—and therefore learn—language. What’s more, these specialized cells may form
part of a brain network enabling us to anticipate other people’s intentions, says Italian
neuroscientist Giacomo Rizzolatti, one of the discoverers of mirror neurons (Rizzolatti
et al., 2006). Because they connect with the brain’s emotional circuitry, mirror neurons
may allow us to “mirror” other people’s emotions in our minds. From an evolutionary
perspective, observing and imitating others is a fundamental human characteristic, so
mirror neurons could even turn out to be a biological basis of culture. Finally, some
researchers believe deficits in the mirror system may underlie disorders, such as autism,
that involve difficulties in imitation and in understanding others’ feelings and inten-
tions (Ramachandran & Oberman, 2006).
Although the discovery of mirror neurons has ignited great excitement in the
field of brain science, let’s take a moment to think critically about what research
has actually found, versus what may—at this point, at least—be mere speculation.
One caution centers around a common fallacy we discussed in Chapter 1: the as-
sumption of causation when only correlational data exist. Just because our own
motor cortex, for example, activates when we see another person engaging in a
motor activity, we cannot conclude that our observation caused our corresponding
mirror neuron A recently discovered class of neu-
ron that fires in response to (“mirroring”) observation
of another person’s actions or emotions.
Primary
somatosensory
cortex
Receives data about
sensations in skin,
muscles, and joints
Visual association
cortex
Analyzes visual data
to form images
Parietal Lobe
Occipital Lobe
Primary
visual cortex
Receives nerve
impulses from
the visual
thalamus
Wernicke’s area
Interprets spoken
and written language
Temporal Lobe
Auditory association cortex
Analyzes data about sound,
so that we can recognize
words or melodies
Primary auditory
cortex
Detects discrete
qualities of sound,
such as pitch
and volume
Broca’s area
Vital for the
formation of
speech
Prefrontal cortex
Associated with
various aspects of
behavior and
personality
Frontal Lobe
Motor cortex
Generates signals
responsible for
voluntary
movements
FIGURE 2.12
The Four Lobes of the Cerebral Cortex
Each of the two hemispheres of the
cerebral cortex has four lobes. Different
sensory and motor functions have been
associated with specific parts of each
lobe, as shown here.

How Does the Brain Produce Behavior and Mental Processes? 71
neural activity (Hickok, 2009). Thus, it would be premature—and dangerous—to
assume that the lack of imitation sometimes found in autism, for example, was
caused by mirror neuron deficit or dysfunction.
Second, and perhaps even more important, is the notion that mirror neuron activity
implies the observer understands the meaning and intent of the action. For example, if
you see Mary grasp a cup, you might infer from the way she grasps it that she intends
to drink from it (rather than, say, give it to someone else). Mirror neuron enthusi-
asts have assumed this type of action-understanding comes with the mirror neuron
package, so to speak—in other words, that mirror neuron activity promotes deeper
understanding of the person’s motives and actions, leading to conclusions that mirror
neurons underlie empathy and social understanding. But research outside the area of
mirror neurons clearly shows that understanding others’ motivations can occur out-
side a mirror neuron system, in part as the result of analytical thinking skills (Hickok,
2010; Keysers, 2010).
In summary, then, while the discovery of mirror neuron circuitry is definitely excit-
ing and may indeed prove to be a promising advance in understanding human thought,
emotion, and behavior, we must remind ourselves that extraordinary claims require
extraordinary evidence—and curb our enthusiasm a little in the meantime.
A. Primary motor
Primary
somatosensory
B. Primary somatosensoryPrimary visual
(buried deep in
rear of brain)
Primary
auditory
and auditory
association areas
swallowing
chewing
leg
toes
sh
ou
ld
er
w
ris
t
sh
ou
lde
r
wr
ist
ha
nd
fin
ge
rs
th
um
b
fa
ce
lip
s
ind
ex
fin
ge
rha
nd
th
um
b
jaw
knee
toes
Primary
motor
FIGURE 2.13
The Motor Cortex and the Somatosensory Cortex
Actions of the body’s voluntary muscles are controlled by the motor cortex in the frontal lobe. The somatosensory cortex
in the parietal lobe processes information about temperature, touch, body position, and pain. This diagram shows the
proportion of tissue devoted to various activities or sensitivities in each cortex.

72 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
The Left Frontal Lobe’s Role in Speech In most people, the left frontal lobe has another
important function: the production of speech (see Figure 2.12). First discovered in
the mid-1800s by French neurologist Paul Broca, damage to this specialized region—
aptly named Broca’s area—can leave a person without the ability to talk. Surprisingly,
though, the ability to understand speech lies elsewhere in the brain. As you might have
guessed, Jill Bolte Taylor’s stroke damaged Broca’s area in her brain, which explains
why she lost her ability to construct language.
The Parietal Lobes To the rear of each frontal lobe lie two large patches of cortex
that specialize in sensation (see Figure 2.12). These parietal lobes allow us to sense the
warmth of a hot bath, the smoothness of silk, the poke of a rude elbow, and the gentle-
ness of a caress. A special parietal strip, known as the somatosensory cortex, mirrors the
adjacent strip of motor cortex we found in the frontal lobe. This somatosensory cortex
has two main functions. First, it serves as the primary processing area for the sensa-
tions of touch, temperature, pain, and pressure from all over the body (Graziano et al.,
2000; Helmuth, 2000). Second, it relates this information to a mental map of the body
to help us locate the source of these sensations (refer to Figure 2.13).
Other maps in the parietal lobes keep track of the position of body parts, so they
prevent you from biting your tongue or stepping on your own toes. And, when your
leg “goes to sleep” and you can’t feel anything but a tingling sensation, you have tem-
porarily interrupted messages from the nerve cells that carry sensory information to
body maps in the parietal lobe.
Besides processing sensation and keeping track of body parts, the right parietal
lobes help us locate, in three-dimensional space, the positions of external objects de-
tected by our senses. This helps us navigate through our day, from getting out of bed
and finding our way into the shower to dressing ourselves, getting ourselves to school
or work, and so on. Meanwhile, the left hemisphere’s parietal lobe has its own spe-
cial talents. It specializes in mathematical reasoning and locating the source of speech
sounds, as when someone calls your name. It also works with the temporal lobe to
extract meaning from speech and writing.
The Temporal Lobes When the phone rings or a horn honks, the sound registers in
your temporal lobes, on the lower side of each cerebral hemisphere (see Figure 2.12).
There, the auditory cortex helps you make sense of sounds.
But the temporal lobes take responsibility for more than just hearing. In most peo-
ple, a specialized section in the left auditory cortex (where it merges into the lower
parietal lobe), known as Wernicke’s area, helps process the meaning of language. When
Jill Bolte Taylor phoned her coworker for help during her stroke, she could hear his
words, but they sounded like gibberish to her. “Oh my gosh, he sounds like a golden
retriever!” she thought (Taylor, 2009, p. 56). This was due to the damage underway in
Wernicke’s area of her brain. And it doesn’t seem to matter if the language is spoken
or signed: Research with hearing-impaired individuals finds that they recruit this same
area in understanding sign language (Neville et al., 1998).
And that’s not all. Portions of the temporal lobes “subcontract” from the visual cor-
tex the work of recognizing faces. Other temporal regions work with the hippocampus
on the important task of storing long-term memories. There is even a distinct patch of
temporal cortex dedicated to perception of the human body (Kanwisher, 2006; Tsao,
2006). Finally, the right temporal lobe plays a significant role in interpreting the emo-
tional tone of language—which explains why the gentle tone of her coworker’s voice
reassured Jill that he would bring help, despite her inability to understand his words
(Taylor, 2009).
The Occipital Lobes Have you ever “seen stars” after a hard bump to your head? If
so, that visual sensation likely resulted from stimulation to your occipital lobes at the
back of your brain (see Figure 2.12). Under more normal circumstances, the occipital
lobes receive messages relayed from the eyes. There, the visual cortex constructs ongoing
images of the world around us.
parietal lobes Cortical areas lying toward the
back and top of the brain; involved in touch sensation
and in perceiving spatial relationships (the relation-
ships of objects in space).
somatosensory cortex A strip of the parietal
lobe lying just behind the central fissure. The somato-
sensory cortex is involved with sensations of touch.
temporal lobes Cortical lobes that process
sounds, including speech. The temporal lobes are
probably involved in storing long-term memories.
occipital lobes The cortical regions at the back
of the brain that house the visual cortex.
visual cortex The visual processing areas of
cortex in the occipital and temporal lobes.

How Does the Brain Produce Behavior and Mental Processes? 73
To create pictures of the outside world, the brain divides up the incoming visual
input and sends it to separate cortical areas for the processing of color, movement,
shape, and shading—as we will see in more detail in Chapter 3. But the occipital lobes
don’t do all this work alone. As we noted previously, they coordinate with adjacent
areas in the parietal lobes to locate objects in space. They also work with temporal
regions to produce visual memories (Ishai & Sagi, 1995; Miyashita, 1995). To complete
the picture, we should note that congenitally blind people recruit the visual cortex to
help them read Braille (Amedi et al., 2005; Barach, 2003).
The Association Cortex In accomplishing its magnificent feats of multitasking,
our brain relies both on the “primary processing areas” of the cortex as well as
the “association areas” of the cortex. The association cortex, named for the belief that
complex thinking relies upon associating ideas with each other, actually constitutes
more than half of the cerebral cortex. But before these associations are made, specific
areas of the cortex must process the raw data streaming in from the sense organs: For
example, the primary visual cortex processes raw visual stimulation, such as the let-
ters in a word and whether any are capitalized. Then the association area takes over
to interpret the meaning of the message, such as perceiving the whole of the word or
sentence. Thus, diverse parts of the association cortex, throughout our lobes, interpret
sensations, lay plans, make decisions, and prepare us for action— precisely the mental
powers in which we humans excel and that distinguish us from other animals.
The Cooperative Brain No single part of the brain, however, takes sole responsi-
bility for emotion, memory, personality, or any other complex psychological char-
acteristic: There are no single “brain centers” for any of our major faculties. Rather,
every mental and behavioral process involves the coordination and cooperation of
many brain networks, each an expert at some highly specialized task (Damasio,
2003; LeDoux, 2002). For example, when you do something as simple as answer
a ringing telephone, you hear it in your temporal lobes, interpret its meaning with
the help of the frontal lobes, visually locate it with your occipital and parietal lobes,
initiate grasping the phone on the orders of your frontal and parietal lobes, and
engage in thoughtful conversation, again using frontal and temporal lobe circuitry.
And the cortex cannot do its work without communicating with circuits lying deep
beneath the surface: the limbic system, thalamus, brain stem, cerebellum, and other
structures.
Clearly, the brain usually manages to “put it all together” in a coordinated effort
to understand and respond to the world. Exactly how it does so is not clear to neuro-
scientists—and, in fact, constitutes one of the biggest mysteries of modern psychology.
Some clues have appeared in recent work, however. Constantly active, even when we
are asleep, our brains produce pulses of coordinated waves sweeping over the cortex
that are thought, somehow, to coordinate activity in far-flung brain regions (Buzsáki,
2006). All these busy neural networks work in elegant coordination with each other
in work and in play, in waking and sleeping, from conception to death—and mostly
without our awareness.
Cerebral Dominance
Throughout our discussion of various brain structures and their associated
functions, we have made some distinctions between functions in the left and right
hemispheres. We know, for example, that a person with injury to the right hemi-
sphere would probably not experience language difficulties but could have trouble
with spatial orientation—for example, feeling lost in a familiar place or unable to
complete a simple jigsaw puzzle. This tendency for each hemisphere to take the lead
in different tasks is called cerebral dominance, an often-exaggerated concept. While
it is true that some processes are more under the control of the left hemisphere
and others are predominantly right-hemisphere tasks, both hemispheres continu-
ally work together to produce our thoughts, feelings, and behaviors—courtesy of
association cortex Cortical regions throughout
the brain that combine information from various other
parts of the brain.
C O N N E C T I O N CHAPTER 3
The puzzle of how the brain “puts
it all together” is known as the
binding problem (p. 113).
cerebral dominance The tendency of each
brain hemisphere to exert control over different func-
tions, such as language or perception of spatial
relationships.

74 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
the corpus callosum and its role in communication between the hemispheres. With
that in mind, what differences are there between the hemispheres?
Language and Communication As we have seen, the left hemisphere usually domi-
nates language functions, although both sides of the brain get involved to some extent.
Typically, the left side is more active in manufacturing and processing the “what,” or
content, of speech. The right hemisphere, by contrast, interprets the emotional tone
of speech (Vingerhoets et al., 2003), as we noted in the case of Jill’s stroke. The right
hemisphere also takes the lead in interpreting others’ emotional responses and their
nonverbal communication signals. As for our own emotions, the control of negative
emotions, such as fear and anger, usually stems from the right frontal lobe, while the
left frontal lobe typically regulates positive emotions such as joy (Davidson, 2000b).
Different Processing Styles Thus, the two hemispheres don’t generally compete
with each other. Rather, they make different contributions to the same task. In the
lingo of neuroscience, the two hemispheres have different but complimentary pro-
cessing styles. For example, the left hemisphere groups objects analytically and ver-
bally—as by similarity in function (knife with spoon)—while the right hemisphere
might match things by form or visual pattern—as in matching coin to clock, which are
both round objects (Gazzaniga, 1970; Sperry, 1968, 1982). In general, we can describe
the left hemisphere’s processing style as more analytic and sequential, while the right
hemisphere interprets experience more holistically, emotionally, and spatially (Reuter-
Lorenz & Miller, 1998). In a normally functioning brain, the two styles complement
each other, combining to produce a multifaceted perspective of the world.
In the wake of damage to the brain, though—such as Jill’s stroke—the different
processing styles may become starkly apparent. In Jill’s case, she relied more on linear
thinking during the first part of her life: “I spent a lifetime of thirty-seven years being
enthusiastically committed to do-do-doing lots of stuff at a very fast pace” (Taylor,
2009, p. 70). The radical shift in her perception caused by the damage to her left hemi-
sphere was noticeable right away, when she found herself incapable of keeping her
thoughts on track while trying to plan how to get help. The step-by-step, time-oriented
thinking she had taken for granted had vanished, and in its place a completely different
perspective of herself and the world emerged. “I felt no rush to do anything (p. 71),”
she marvels, as she remembers her joy in feeling connected to everything around her, in
being exquisitely tuned to others’ emotions, in taking time to ponder things, and in the
deep inner peace that came with her new view of the world that emphasized the right
brain’s perspective.
If that description sounds like words a person might use to describe a religious or
spiritual experience, neurological studies from the University of Pennsylvania may tell
us why. Researchers conducted sophisticated brain scans on people who were meditat-
ing and found that in peak meditative states, activity in the left association cortex—the
area that makes us aware of our body’s physical boundaries—declined sharply. Thus,
the self-transcendence reported by expert meditators, as well as Jill Taylor’s similar
feeling of being “one with the universe,” appear to have a biological basis: When blood
flow to that region of the left hemisphere slows down, our awareness of ourselves as
separate and distinct organisms fades (Newberg et al., 2001a). In addition, decreased
activity in the left parietal lobe, also noted in studies of meditators, correlates with an
altered awareness of one’s body in relation to space (Newberg et al., 2001b).
Some People Are Different—But That’s Normal Just to complicate your picture
of cerebral dominance, dominance patterns are not always the same from one person
to another. Research demonstrating this fact uses a technique called transcranial mag-
netic stimulation (TMS) to deliver powerful magnetic pulses through the skull and into
the brain. There, the magnetic fields interfere with the brain’s electrical activity, tempo-
rarily disabling the targeted region without causing permanent damage. Surprisingly,
when the left-side language areas receive TMS, language abilities in some people—
mostly left-handers—remain unaffected. In general, these studies show that about one
C O N N E C T I O N CHAPTER 9
Emotional intelligence includes the
ability to perceive and understand
others’ emotions (p. 396).

How Does the Brain Produce Behavior and Mental Processes? 75
in ten individuals process language primarily on the right side of the brain. Another
one in ten—again, mostly left-handers—have language functions distributed equally
on both sides of the brain (Knecht et al., 2002).
Male and Female Brains In a culture where bigger is often seen as better, the unde-
niable fact that men (on average) have slightly larger brains than do women has caused
heated debate. The real question, of course, is: What is the meaning of the size differen-
tial? Most neuroscientists think it is simply related to the male’s larger body size—and
not of much other importance (Brannon, 2008).
Within the brain, certain structures exhibit sex differences too. A part of the
hypothalamus commonly believed to be associated with sexual behavior and, perhaps,
gender identity, is larger in males than in females. Some studies have suggested that
male brains are more lateralized, while females tend to distribute abilities, such as
language, across both hemispheres, although findings in this area are mixed (Sommer
et al., 2004). If true, however, the difference in lateralization may explain why women
are more likely than men to recover speech after a stroke. Other than that, what
advantage the difference in lateralization may have is unclear.
At present, no one has nailed down any psychological difference that can be
attributed with certainty to physical differences between the brains of males and
females. The research continues, but we suggest interpreting new claims with a liberal
dose of critical thinking, being especially wary of bias that may influence the way
results are interpreted. In fact, we will help you do just that in the Critical Thinking:
Applied section at the end of this chapter.
The Strange and Fascinating Case of the Split Brain Imagine what your world
might be like if your two hemispheres could not communicate—if your brain were,
somehow, “split” in two. Would you be, literally, “of two minds”? (See Figure 2.14.)
This is not an idle question, because there are people with “split brains,” the result of a
last-resort surgical procedure used to treat a rare condition of almost continuous epi-
leptic seizures. Before their surgery, these patients produced abnormal electrical bursts
of brain waves that seemed to “echo” back and forth between the hemispheres, quickly
building into a seizure—much as feedback through a microphone generates a loud
screeching noise. So the idea was to cut the corpus callosum—severing the connection
between the hemispheres—and thereby prevent the seizure from raging out of control.
But was there a psychological price? Curiously, split-brain patients appear mentally
and behaviorally unaffected by this extreme procedure under all but the most unusual
conditions.
Those unusual conditions involve clever tests contrived by Nobel Prize winner
Roger Sperry (1968) and his colleague Michael Gazzaniga (2005). For example,
when holding a ball in the left hand (without being able to see it), as shown in
Corpus callosum
FIGURE 2.14
The Corpus Callosum
Only the corpus callosum is severed when
the brain is “split.” This medical proce-
dure prevents communication between
the cerebral hemispheres. Surprisingly,
split-brain patients act like people with
normal brains under most conditions.
Special laboratory tests, however, reveal
a duality of consciousness in the split
brain.

76 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
Figure 2.15, their split-brain patients could not identify it by touch, yet they had no
trouble doing so when the ball was transferred to the right hand. In another test,
split-brain patients said they saw nothing when an image of a spoon flashed briefly
on the left side of the visual field. Yet, they could reach around a visual barrier with
the right hand and easily pick the spoon out of an array of other objects.
How can we explain these odd findings? Let’s see if we can use what we have
learned in this chapter to solve this peculiar puzzle.
• First, remember that the corpus callosum enables communication between the
hemispheres—so, when it is severed, each hemisphere must process information
on its own. This explains, also, why split-brain patients can simultaneously draw a
circle with one hand and a square with the other (a near-impossible task for those
with intact brains. If you don’t believe us, just try it!)
• Because the sensory pathways cross over to the opposite side as they ascend to the
cortex, each side of the body communicates with the opposite side of the brain. So,
each hemisphere perceives touch sensation from the hand on the opposite side of
the body.
• Language is usually a left-hemisphere function. This, when combined with the
contralateral sensory pathways, explains why these patients could name ob-
jects when they were processed in the left hemisphere. When sensory messages
came in from the right visual field or the right hand (such as holding the ball
in the right hand), the message crossed over to the left hemisphere, which—
thanks to its language abilities—could name the object. Conversely, objects
seen in the left visual field or felt in the left hand crossed over to the right
hemisphere for processing, where—because the right hemisphere cannot pro-
duce speech—patients could not name the object. They could, however, identify
it by touch.
In another study with a similar patient, Gazzaniga found something else remark-
able. He began with images of paintings by an artist named Giuseppe Arcimboldo,
famous for painting faces made entirely of figures, such as fruit, books, fish, and other
objects (see the accompanying photo). Would the patient’s left hemisphere’s perception
of the painting differ from his right hemisphere’s view of it? (If you enjoy a challenge,
try to remember something we discussed a few pages back that may help you figure
out the answer before reading on.)
could not identify verbally could identify verbally
? “ball”
FIGURE 2.15
Testing a Split-Brain Patient
Split-brain patients can name unseen
objects placed in the right hand, but
when an object is placed in the left hand,
they cannot name it. Why?
FIGURE 2.16
The Neural Pathways from the Eyes to
the Visual Cortex
There are two things to notice in this
illustration in which the person is look-
ing at the center of the pizza. First, the
information from the left side of the retina
in each eye (which is the left visual field)
corresponds to the right side of the pizza.
Conversely, the right visual field senses
the left side of the pizza. (This happens
because the lens of the eye reverses the
image.) Second, please notice that the
optic nerves of both eyes join together at
the optic chiasm, where information
from the left sides of both retinas are
routed to the left visual cortex, while
images from the right sides of both reti-
nas are routed to the right visual cortex.
As a result, everything a person sees on
the right gets processed in the left hemi-
sphere’s visual cortex, while the right visual
cortex processes everything to the left of
the point on which the eyes are fixed.

How Does the Brain Produce Behavior and Mental Processes? 77
When the images were flashed briefly to his right visual
field (and thus processed in his left hemisphere), he recognized
only the objects in the image (such as fruit or books)—he did
not “see” a face. When shown to his left visual field, however,
the processing style of his right hemisphere enabled his recog-
nition of a human face. This finding supports other research
indicating a special ability for facial recognition in the right
hemisphere (The Man with Two Brains, 1997). Clearly, both
hemispheres play important roles in human abilities.
Two Consciousnesses Such cerebral antics point to the most
interesting finding in Sperry and Gazzaniga’s work: the duality
of consciousness observed in split-brain patients. When the two
hemispheres received different information, it was as if the pa-
tient were two separate individuals. One patient told how his
left hand would unzip his pants or unbutton his shirt at most
inappropriate times, especially when he felt stressed. Another
reported his misbehaving left hand turning off the television in
the middle of a program he had been watching (Joseph, 1988).
Why? Sperry theorized that the right hemisphere—which has
little language ability, but which controls the left hand—was
merely trying to find a way to communicate by getting attention
any way it could (Sperry, 1964).
We must, however, be cautious about generalizing such
findings from split-brain patients to individuals with normal
brains. Gazzaniga (1998a, b) suggests we think of the human
mind as neither a single nor a dual entity but rather as a con-
federation of minds, each specialized to process a specific kind
of information. For most people, then, the corpus callosum
serves as a connecting pathway that helps our confederation
of minds share information. And so we come full circle to the Core Concept we en-
countered at the beginning of this section: The brain is composed of many special-
ized modules that work together to create mind and behavior (Baynes et al., 1998;
Strauss, 1998).
What’s It to You? Nearly everybody knows someone who has suffered brain damage
from an accident, a stroke, or a tumor. Your new knowledge of the brain and behavior
will help you understand the problems such people face. And if you know what
abilities have been lost or altered, you can usually make a good guess as to which
part of the brain sustained the damage—especially if you bear in mind three simple
principles:
1. Each side of the brain communicates with the opposite side of the body. Thus,
if symptoms appear on one side of the body, it is likely that the other side of the
brain was damaged (see Figure 2.17).
2. For most people, speech is mainly a left-hemisphere function.
3. Each lobe has special functions:
• The occipital lobe specializes in vision;
• The temporal lobe specializes in hearing, memory, and face recognition;
• The parietal lobe specializes in locating sensations in space, including the
surface of the body;
• The frontal lobe specializes in motor movement, the production of speech,
and certain higher mental functions that we often call “thinking” or
“intelligence.”
Right brain
damage
Paralyzed
left side
Spatial
perceptual
defects
Behavioral
style—quick,
impulsive
Memory
deficits—
performance
Left brain
damage
Paralyzed
right side
Speech,
language
deficits
Behavioral
style—slow,
cautious
Memory
deficits—
language
FIGURE 2.17
Contralateral Effects of Damage to the
Cerebral Hemispheres
A painting by Arcimboldo, who painted
faces made of fruits, flowers, and books,
and other figures. Gazzaniga used
Arcimboldo’s paintings to show how the
two hemispheres process facial images
differently.

78 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
Here’s how one of your authors (Bob) applied his knowledge of the brain:
I hadn’t noticed Dad dragging the toe of his right foot ever so slightly as he
walked. But my Mom noticed it on their nightly tour of the neighborhood,
when he wasn’t keeping up with her brisk pace. I just figured he was slowing
down a bit in his later years.
Dad, too, casually dismissed his symptom, but Mom was persistent. She
scheduled an appointment with the doctor. In turn, the doctor scheduled a brain
scan that showed a remarkably large mass—a tumor—on the left side of Dad’s
brain. You can see what the neurologist saw in Figure 2.18—an image taken
ear-to-ear through the head.
When I saw the pictures, I knew immediately what was happening. The tu-
mor was located in an area that would interfere with tracking the position of
the foot. I knew that each side of the brain communicates with the opposite side
of the body—so it made sense that the tumor showing so clearly on the left side
of Dad’s brain (right side of the image) was affecting communications with his
right foot.
The neurologist also told us that the diseased tissue was not in the brain
itself. Rather, it was in the saclike layers surrounding the brain and spinal cord.
That was good news, in an otherwise bleak report. Still, the mass was growing
and putting pressure on the brain. The recommendation was surgery—which
occurred after an anxious wait of a few weeks.
During this difficult time, I remember feeling grateful for my professional
training. As a psychologist, I knew something about the brain, its disorders,
and treatments. This allowed me to shift perspectives—from son to psycholo-
gist and back again. It helped me deal with the emotions that rose to the surface
when I thought about the struggle for the organ of my father’s mind.
Sadly, the operation did not produce the miraculous cure for which we had
hoped. Although brain surgery is performed safely on thousands of patients
each year—many of whom receive immense benefits in the quality and lengths
of their lives—one has to remember that it is a procedure usually done on very
FIGURE 2.18
MRI Image of a Brain Tumor
This image, showing a side-to-side sec-
tion toward the back of the head, reveals
a large mass on the left side of the brain
in a region involved with tracking the po-
sition of the right foot. Visible at the bot-
tom is a cross-section of the cerebellum.
Also visible are the folds in the cerebral
cortex covering the brain. Near the center,
you can see two of the brain’s ventricles
(hollow spaces filled with cerebrospinal
fluid), which are often enlarged, as they
are here, in Alzheimer’s disease. The scan
is of the father of one of your authors.

How Does the Brain Produce Behavior and Mental Processes? 79
sick people. In fact, the operation did give Dad some time with us that he may
otherwise not have had.
PSYCHOLOGY MATTERS
Using Psychology to Learn Psychology
The old idea that we use only 10 percent of our brains is nonsense that probably came
from a time when neuroscientists hadn’t figured out the functions of many cortical ar-
eas. Now we know that every part of the brain has a specific function, and they all get
used every day. Therefore, simply finding a way to engage more of the brain is not the
royal road to increased brainpower.
Have neuroscientists found anything you can use to improve your memory, espe-
cially for concepts you are learning in your classes? The fact that we employ many dif-
ferent regions of the cerebral cortex in learning and memory may be among their most
practical discoveries (Kandel & Squire, 2000). Accordingly, if you can bring more of
this cerebral circuitry to bear on your studies (about biopsychology, for example), your
brain will develop a wider web of memories.
Reading the material in this book will help you form verbal (language) memories, parts
of which involve circuits in the temporal cortex. Taking notes brings the motor cortex of
the frontal lobes into play, adding a “motor memory” component to your study. Studying
the accompanying photos, charts, and drawings adds visual and spatial memory compo-
nents in the occipital and parietal lobes. Listening actively to your professor’s lectures and
discussing the material with a study partner will engage the auditory regions of the tem-
poral cortex and create still more memory traces. Finally, anticipating questions that may
appear on the exam will involve regions of the frontal lobes in your learning process.
In general, the more ways you can engage with the material—the more sensory
and motor channels you can employ—the more memory components you will build in
your brain’s circuitry. As a result, you will have more ways of accessing what you have
learned when you need to remember the material.
Answers 1. fMRI would be best, because it not only gives detailed three-dimensional images but also shows different activity levels in different
parts of the brain. The driving task, however, would have to be modified so it could be performed while in the fMRI machine. 2. The brain stem and
cerebellum, the limbic system, the cerebrum 3. limbic system 4. See the location of the four lobes in Figure 2.12. The left hemisphere controls
language, and the right hemisphere controls your left hand. 5. right 6. Examples include the interaction of regions in the four lobes of the cerebral
cortex when answering the phone. There are many other examples mentioned in this section.
Check Your Understanding
1. APPLICATION: Suppose you are a neuroscientist interested in
comparing what parts of the brain are most active when people
are driving and talking on a cell phone. Which imaging technique
would be best for your research?
2. RECALL: Name the three main layers of the human brain
discussed in the text: , , and .
3. APPLICATION: An fMRI or a PET scan would show activity in a
person’s during an emotional response.
4. RECALL: Make a sketch showing the four lobes of the cerebral
cortex. Indicate the main functions of each lobe and which
hemisphere controls language in most people. Which hemisphere
controls the left hand?
5. ANALYSIS: A split-brain patient would have trouble using his
hand to select the object flashed on the left side of
the screen. (Hints: Which hemisphere controls each hand? Which
hemisphere processes information from the left side of the visual
field?)
6. UNDERSTANDING THE CORE CONCEPT: The brain is
composed of many specialized and interconnected modules that
work together to create mind and behavior. Can you name at
least two specialized parts of the brain that are known to work
together?
Study and Review at MyPsychLab

80 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
CRITICAL THINKING APPLIED
Left Brain versus Right Brain
Would you rather solve a math problem or create a paint-ing? Write an essay on an academic topic or invent a
fictional story? According to pop science, the way you answer
questions like this reveals whether you are a “left-brain” per-
son or a “right-brain” person. Furthermore, the same sources
often then encourage you to use that information to choose a
career. Is there any truth to these claims?
The split-brain studies and discovery that the two sides
of the brain process information differently have certainly
captured public interest. Press reports claiming the left
hemisphere is logical and the right hemisphere is emotional
might easily lead to the mistaken conclusion that your friend
Jamal, a guy with an analytic bent, lives mostly in his left
hemisphere, while his wife Barb, more sensitive to people’s
emotions, filters her experience mainly through the right side
of her brain.
Knowing a fad when they see it, pseudoscientists have
developed workshops to help plodding analytical types get
into their “right minds.” Before you jump on this particular
bandwagon, though, let’s dig a little deeper.
What Are the Critical Issues?
The idea that people fall neatly into one category or another
has popular appeal, but do the facts bear this out? Recent
findings in neuroscience should be able to tell us how the left
and right brain interact and whether people really are right-
or left-brained.
Is the Claim Reasonable or Extreme? As we have seen
in this chapter, the notion that we rely on one side of the
brain, largely to the exclusion of the other, is an exaggera-
tion. Rather, we use both sides, in coordination with each
other, all the time. As we often find in extreme claims, the
“left brain vs. right brain” issue has oversimplified the sci-
entific findings of hemispheric differences: People rarely fit
neatly into one of two dichotomous categories. This serves
as a good example of how honest findings (such as the
work reported in this chapter on the differences between
the hemispheres) often become wildly exaggerated by the
time they reach the popular news media. We should always
digest these reports with a healthy dose of skepticism and
look closely at the evidence.
What Is the Evidence? As we have seen, the two hemi-
spheres have somewhat different processing styles, but the
actual differences between the two hemispheres do not out-
weigh their similarities (Banich, 1998; Trope et al., 1992).
Most important—and what the right-brain/left-brain faddists
overlook—is that the two hemispheres of the intact brain co-
operate with each other, each making its own complementary
contribution to our mental lives (see Figure 2.17).
Could Bias Contaminate the Conclusion? Two biases
come easily to mind as we consider this issue. First—as we
mentioned earlier—some businesses have made fortunes
“selling” this idea, which creates an obvious bias if these
same businesses are trying to convince you of its veracity.
Emotional bias is likely present as well. After all, we humans
like to classify things and people into categories: It appeals to
our sense of order and soothes our need to resolve complex
issues. Small wonder, then, that we often latch on to typolo-
gies that purport to explain human nature, characteristics,
and behavior.
What Conclusions Can We Draw?
Unless you have a split brain, you bring the abilities of
both sides of your brain to bear on everything you do.
Why, then, do people have such obvious differences in the
way they approach the same tasks? Some people do seem
to approach things in a more analytical, logical fashion;
others operate from a more intuitive and emotional per-
spective. But now that you know something of how the
brain works, you understand that we cannot account for
these differences simply by suggesting people employ one
side of their brain or the other. Even split-brain patients use
both sides of their brains! A better explanation involves
different combinations of experience and brain physiology.
People are different because of different combinations of
nature and nurture—not because they use opposite sides
of the brain.

Chapter Summary 81
USING BOTH SIDES OF YOUR BRAIN
Think of something you enjoy doing—it
might be playing a particular sport or
making music, cooking or having dinner
with friends, studying or shopping, or
whatever strikes your fancy. Now, imagine
doing it for a couple of hours and all the
minute details of what would likely oc-
cur in that period of time. Make a note
of some of them and then try to identify
which parts of the activity might be led
by your left hemisphere and which parts
of the activity are more likely coordinated
by your right hemisphere. (Hint: Besides
all the examples included earlier in the
chapter, we have listed some in
Figure 2.19.)
Chances are, in any pursuit, you’ll
see how involved both hemispheres need
to be in order for you to fully engage in
the experience. And because of that, you
stand as living proof that you are neither
“left-brained” nor “right-brained,” but
a beautifully coordinated example of
“whole-brained!”
• Regulation of positive
emotions
• Control of muscles used
in speech
• Control of sequence of
movements
• Spontaneous speaking
and writing
• Memory for words and
numbers
• Understanding speech
and writing
• Regulation of
negative emotions
• Responses to simple
commands
• Memory for shapes
and music
• Interpreting spatial
relationships and
visual images
• Recognition of faces
Left hemisphere Right hemisphere
FIGURE 2.19
Specialization of the Cerebral Hemispheres
While each hemisphere communicates with the opposite side of the body, the hemispheres
each specialize in controlling different functions. For most people, the left hemisphere spe-
cializes in speech and other functions performed in sequence (such as walking, throwing,
and reading). The right hemisphere specializes in synthesis: gathering many pieces of
information and synthesizing it as a unified whole (as in recognizing faces or shapes).
CHAPTER PROBLEM: What does Jill Bolte Taylor’s
experience teach us about how our brain is organized and about its
amazing ability to adapt?
• Our brain communicates through contralateral pathways, so
that sensory information from one side of the body is processed
by the opposite cerebral hemisphere.
• Brain plasticity allows us to regain or rewire functions lost due
to damage or trauma.
• Our brain is composed of a group of specialized structures,
each of which performs certain tasks, but which all work
together to produce thought, behavior, and emotion.
CHAPTER SUMMARY
2.1 How Are Genes and Behavior Linked?
Core Concept 2.1 Evolution has fundamentally shaped
psychological processes because it favors genetic variations
that produce adaptive behavior.
Charles Darwin’s theory of evolution explains behavior as
the result of natural selection. Variation among individuals and
competition for resources lead to survival of the most adap-
tive behavior as well as the fittest physical features. This prin-
ciple underlies human behavior as well as that of other animals.
Genetics has clarified the biological basis for natural selection
and inheritance. Our chromosomes contain thousands of genes,
carrying traits inherited from our parents. Each gene consists
of a DNA segment that encodes for a protein. Proteins, in turn,
serve as the building blocks for the organism’s structure and
function, including the functioning of the brain. While a draft
of the human genome has been completed, we do not yet know
precisely how specific genes influence behavior and mental
processes. Genetic research is nearing the point at which we
may alter our genetic makeup or select certain genetic traits for
our children. This new knowledge brings with it ethical choices
that humans have never had to face before.
Listen at MyPsychLabto an audio file of your chapter

82 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
biopsychology (p. 42)
chromosome (p. 46)
corpus callosum (p. 68)
DNA (deoxyribonucleic
acid) (p. 46)
evolution (p. 43)
gene (p. 46)
genotype (p. 45)
genome (p. 46)
natural selection (p. 44)
phenotype (p. 45)
sex chromosomes (p. 46)
2.2 How Does the Body Communicate
Internally?
Core Concept 2.2 The brain coordinates the body’s
two communications systems, the nervous system and the
endocrine system, which use similar chemical messengers to
communicate with targets throughout the body.
The body’s two communication systems are the nervous system
and the endocrine system. Neurons receive messages by means
of stimulation of the dendrites and soma. When sufficiently
aroused, a neuron generates an action potential along the axon.
Neurotransmitter chemicals relay the message to receptors on
cells across the synapse. The nervous system has two main
divisions: the central nervous system and the peripheral nervous
system. The peripheral nervous system, in turn, comprises the
somatic nervous system (further divided into sensory and motor
pathways) and the autonomic nervous system, which communi-
cates with internal organs and glands. The sympathetic division
of the autonomic nervous system is most active under stress,
while the parasympathetic division attempts to maintain the body
in a calmer state. The glands of the slower endocrine system
also communicate with cells around the body by secreting
hormones into the bloodstream. Endocrine system activity is
controlled by the pituitary gland, attached to the base of the
brain, where it receives orders from the hypothalamus. Psycho-
active drugs affect the nervous system by influencing the effects
of neurotransmitters by acting as agonists or antagonists. Un-
fortunately for people taking psychoactive drugs, many neural
pathways in the brain may employ the same neurotransmitter,
causing unwanted side effects.
action potential (p. 52)
agonists (p. 61)
all-or-none principle (p. 53)
antagonists (p. 61)
autonomic nervous system (p. 57)
axon (p. 52)
central nervous system (CNS) (p. 56)
contralateral pathways (p. 57)
dendrite (p. 51)
endocrine system (p. 58)
glial cell (p. 55)
hormones (p. 59)
interneuron (p. 51)
motor neuron (p. 50)
nervous system (p. 56)
neural pathways (p. 61)
neuron (p. 50)
neurotransmitter (p. 53)
parasympathetic division (p. 58)
peripheral nervous system (PNS) (p. 57)
pituitary gland (p. 60)
plasticity (p. 55)
reflex (p. 56)
resting potential (p. 52)
reuptake (p. 53)
sensory neuron (p. 50)
soma (p. 52)
somatic nervous system (p. 57)
sympathetic division (p. 57)
synapse (p. 53)
synaptic transmission (p. 53)
terminal buttons (p. 53)
2.3 How Does the Brain Produce Behavior
and Mental Processes?
Core Concept 2.3 The brain is composed of many
specialized modules that work together to create mind and
behavior.
In modern times, researchers have opened windows on the
brain, using the EEG to sense the brain’s electrical activity. In
recent years, computer technology has led to brain-scanning
techniques, such as CT, PET, MRI, and fMRI—each having its
advantages and disadvantages. We can conceive of the brain as
being organized in three integrated layers. The brain stem and
associated structures (including the medulla, reticular forma-
tion, pons, thalamus, and cerebellum) control many vital body
functions, along with influencing alertness and motor move-
ment. The limbic system (including the hippocampus, amygdala,
and hypothalamus) plays a vital role in motivation, emotion, and
memory. The cerebral cortex contains highly specialized modules.
Its frontal lobes control motor functions, including speech, and
higher mental functions. The parietal lobes specialize in sensation,
especially the senses of touch and body position, as well as the
understanding of speech. The occipital lobes deal exclusively with
vision, while the temporal lobes have multiple roles involved in
face recognition, hearing, and smell. Even though the functions
of the brain are highly localized within specific modules, they
normally work seamlessly together: Every mental and behav-
ioral process involves the coordination and cooperation of many
brain networks. The association cortex integrates the multitude of
raw data into a coherent perception. While the two hemispheres
are more similar than different, they are each equipped with

specialties. Language, analytical thinking, and positive emotions
are regulated primarily by circuits in the left hemisphere. The
right hemisphere specializes in spatial interpretation, visual and
musical memory, and negative emotions. The two hemispheres
communicate across the corpus callosum. If the hemispheres are
surgically severed, as when the corpus callosum is cut in split-
brain patients, a duality of consciousness emerges. Because each
side of the body has sensory and motor links to the opposite
side of the brain, a split-brain patient who “sees” an object in
only one hemisphere of the brain will only be able to locate that
object by touch using the hand linked to the same hemisphere.
amygdala (p. 68)
association cortex (p. 73)
brain stem (p. 65)
cerebellum (p. 66)
cerebral cortex (p. 69)
cerebral dominance (p. 73)
cerebral hemispheres (p. 68)
corpus callosum (p. 68)
CT scanning or computerized tomography (p. 64)
electroencephalograph (EEG) (p. 63)
fMRI or functional magnetic resonance imaging (p. 64)
frontal lobes (p. 69)
hippocampus (p. 67)
hypothalamus (p. 68)
limbic system (p. 66)
medulla (p. 66)
mirror neuron (p. 70)
motor cortex (p. 69)
MRI or magnetic resonance imaging (p. 64)
occipital lobes (p. 72)
parietal lobes (p. 72)
PET scanning or positron emission tomography (p. 64)
pons (p. 66)
reticular formation (p. 66)
somatosensory cortex (p. 72)
temporal lobes (p. 72)
thalamus (p. 66)
visual cortex (p. 72)
analytical or intuitive. A closer look at the evidence for hemi-
spheric specialization, however, reveals that this dichotomy is
wildly oversimplied.
CRITICAL THINKING APPLIED
Left Brain versus Right Brain
Pop science dichotomizes people into left-brained and right-
brained people, based on whether they tend to be more
Chapter Summary 83

84 C H A P T E R 2 Biopsychology, Neuroscience, and Human Nature
Program Review
6. Research related to acetylcholine may someday help people who
a. have Alzheimer’s disease.
b. have Parkinson’s disease.
c. suffer spinal cord trauma.
d. suffer from depression.
7. When we say the relationship between the brain and behavior is
reciprocal, we mean that
a. the brain controls behavior, but behavior can modify the
brain.
b. behavior determines what the brain will think about.
c. the brain and behavior operate as separate systems with no
interconnection.
d. the brain alters behavior as it learns more about the world.
8. Which of the following is true about how neurons communicate
with each other?
a. All neuronal communication is excitatory.
b. Neurons communicate with each other by sending electrical
discharges across the connecting synapse.
c. Neurons of any given type can communicate only with other
neurons of the same type.
d. The sum of excitatory and inhibitory signals to a neuron deter-
mines whether and how strongly it will respond.
9. Which part of the brain controls breathing?
a. cerebellum c. hypothalamus
b. brain stem d. limbic system
1. What section of a nerve cell receives incoming information?
a. axon
b. terminal button
c. synapse
d. dendrite
2. In general, neuroscientists are interested in the
a. brain mechanisms underlying normal and abnormal behavior.
b. biological consequences of stress on the body.
c. comparison of neurons with other types of cells.
d. computer simulation of intelligence.
3. Which section of the brain coordinates body movement and main-
tains equilibrium?
a. brain stem
b. cerebellum
c. hippocampus
d. cerebrum
4. Which brain structure is most closely involved with emotion?
a. cortex c. limbic system
b. brain stem d. cerebellum
5. Which method of probing the brain produces actual pictures of
the brain’s inner workings?
a. autopsies c. brain imaging
b. lesioning d. electroencephalograms
FPO
DISCOVERING PSYCHOLOGY VIEWING GUIDE
Watch the following videos by logging into MyPsychLab (www.mypsychlab.com). After you have
watched the videos, answer the questions that follow.
PROGRAM 3: THE BEHAVING BRAIN

PROGRAM 4: THE RESPONSIVE BRAIN

PROGRAM 25: COGNITIVE NEUROSCIENCE

www.mypsychlab.com

Discovering Psychology Viewing Guide 85
10. The cerebrum
a. consists of two hemispheres connected by the corpus
callosum.
b. relays sensory impulses to the higher perceptual
centers.
c. releases seven different hormones to the pituitary gland.
d. controls temperature and blood pressure.
11. After a rod was shot through Phineas Gage’s skull, what psycho-
logical system was most strongly disrupted?
a. his emotional responses
b. his ability to sleep and wake
c. his language comprehension
d. his ability to count
12. Which of the following does not provide information about the
structure of the brain?
a. CAT c. MRI
b. EEG d. fMRI
13. Which of the following provides the highest temporal and spatial
resolution in brain imaging?
a. ERP c. PET
b. MRI d. fMRI
14. Stimuli that pass through the right eye are processed by
a. the left side of the brain.
b. the front of the brain.
c. the right side of the brain.
d. the brain stem.
15. The process of learning how to read shows that the brain is plas-
tic. What does this mean?
a. The brain is rigid in what it is designed to do.
b. Learning how to read reorganizes the brain.
c. The brain cannot be damaged simply by attempting new men-
tal feats.
d. The brain can be damaged when it attempts new mental feats.
16. If a scientist was studying the effects of endorphins on the body,
the scientist would be likely to look at a participant’s
a. memory.
b. mood.
c. ability to learn new material.
d. motivation to compete in sports.
17. What is the relationship between the results of Saul Schanberg’s
research and that of Tiffany Field?
a. Their results are contradictory.
b. The results of Schanberg’s research led to Field’s research.
c. Their results show similar phenomena in different species.
d. Their results are essentially unrelated.
18. What physical change did Mark Rosenzweig’s team note when it
studied rats raised in an enriched environment?
a. a thicker cortex
b. more neurons
c. fewer neurotransmitters
d. no physical changes were noted, only functional changes
19. A scientist who uses the methodologies of brain science to exam-
ine animal behavior in natural habitats is a
a. naturalist.
b. bioecologist.
c. neuroethologist.
d. cerebroetymologist.
20. With respect to the neurochemistry of the brain, all of these are
true, except that
a. scopolamine blocks the establishment of long-term
memories.
b. opioid peptides are naturally occurring chemicals in
the brain.
c. physostigmine is responsible for information transmission in
the perceptual pathways.
d. endorphins play a major role in pleasure and pain
experiences.

Sensation and Perception3
Psychology MattersCore ConceptsKey Questions/Chapter Outline
3.1 How Does Stimulation Become
Sensation?
Transduction: Changing Stimulation to
Sensation
Thresholds: The Boundaries of Sensation
Signal Detection Theory
The brain senses the world indirectly
because the sense organs convert
stimulation into the language of the
nervous system: neural messages.
Sensory Adaptation
We get used to all but the most
extreme or obnoxious stimuli because
our senses are built to tell us about
change.
3.2 How Are the Senses Alike?
How Are They Different?
Vision: How the Nervous System Processes
Light
Hearing: If a Tree Falls in the Forest . . .
How the Other Senses Are Like Vision and
Hearing
Synesthesia: Sensations across the Senses
The senses all operate in much the
same way, but each extracts different
information and sends it to its own
specialized processing region in the
brain.
The Experience of Pain
Pain is more than just a stimulus;
it is an experience that varies from
person to person. Pain control methods
include drugs, hypnosis, and—for
some—placebos.
Perception brings meaning to
sensation, so perception produces
an interpretation of the world, not a
perfect representation of it.
Using Psychology to Learn
Psychology
Don’t set aside a certain amount of
time for studying. Instead, study for
the Gestalt.
CHAPTER PROBLEM Is there any way to tell whether the world we “see” in our minds is the same
as the external world—and whether we see things as most others do?
CRITICAL THINKING APPLIED Subliminal Perception and Subliminal Persuasion
3.3 What Is the Relationship between
Sensation and Perception?
Perceptual Processing: Finding Meaning
in Sensation
Perceptual Ambiguity and Distortion
Theoretical Explanations for Perception
Seeing and Believing

87
C AN YOU IMAGINE WHAT YOUR WORLD WOULD BE LIKE IF YOU COULD NO LONGER see colors—but merely black, white, and gray? Such a bizarre sensory loss befell Jonathan I., a 65-year-old New Yorker, following an automobile accident. Details of his case appear in neurologist Oliver Sacks’s 1995 book, An Anthropologist on Mars.
The accident caused damage to a region in Jonathan’s brain that processes color in-
formation. At first, he also experienced amnesia for reading letters of the alphabet, which
all seemed like a jumble of nonsensical markings. But, after five days, his inability to read
disappeared. His loss of color vision, however, persisted as a permanent condition, known
as cerebral achromatopsia (pronounced ay-kroma-TOP-see-a). Curiously, Jonathan also lost
his memory for colors: He could no longer imagine, for instance, what “red” once looked like.
As you might expect, Jonathan became depressed by this turn in his life. And the prob-
lem was aggravated by his occupation. You see, Jonathan was a painter who had based his
livelihood on representing his visual images of the world in vivid colors. Now this whole world
of color was gone. Everything was drab—all “molded in lead.” When he looked at his own
paintings now, paintings that had seemed bursting with special meaning and emotional as-
sociations, all he could see were unfamiliar and meaningless objects on canvas.
Still, Jonathan’s story has a more or less happy ending, one that reveals much about the
resilience of the human spirit. Jonathan became a “night person,” traveling and working at
night and socializing with other night people. (As we will see in this chapter, good color vision
depends on bright illumination such as daylight; most people’s color vision is not as acute in
the dark of night.) He also became aware that what remained of his vision was remarkably

88 C H A P T E R 3 Sensation and Perception
good, enabling him to read license plates from four blocks away at night. Jonathan began to
reinterpret his “loss” as a “gift” in which he was no longer distracted by color so that he could
now focus his work more intensely on shape, form, and content. Finally, he switched to painting
only in black and white. Critics acclaimed his “new phase” as a success. He has also become a
skilled sculptor, which he had never attempted before his accident. So, as Jonathan’s world of
color died, a new world of “pure forms” was born in his perception of the people, objects, and
events in his environment.
What lessons can we learn from Jonathan’s experience? His unusual sensory loss tells
us that our picture of the world around us depends on an elaborate sensory system that
processes incoming information. In other words, we don’t experience the world directly, but
instead through a series of “filters” that we call our senses. By examining such cases of sen-
sory loss, psychologists have learned much about how the sensory processing system works.
And, on a more personal level, case studies like Jonathan’s allow us momentarily to slip
outside our own experience to see more clearly how resilient humans can be in the face of
catastrophic loss.
But Jonathan’s case also raises some deeper issues. Many conditions can produce the
inability to see colors: abnormalities in the eyes, the optic nerve, or the brain can interfere
with vision and, specifically, with the ability to see colors, as Jonathan’s case illustrates. But
do colors exist in the world outside us—or is it possible that color is a creation of our brains?
At first, such a question may seem absurd. But let’s look a little deeper. Yes, we will argue
that color—and, in fact, all sensation—is a creation of the brain. But perhaps the more profound
issue is this:
PROBLEM: Is there any way to tell whether the world we “see” in our minds is the same
as the external world—and whether we see things as most others do?
This chapter will show you how psychologists have addressed such questions. The chapter
also takes us the next logical step beyond our introduction to the brain to a consideration
of how information from the outside world gets into the brain and how the brain makes
sense of it.
Although the very private processes that connect us with the outside world extend
deep into the brain, we will begin our chapter at the surface—at the sense organs. This
is the territory of sensory psychology. We will define sensation simply as the process
by which a stimulated receptor (such as the eyes or ears) creates a pattern of neural
messages that represent the stimulus in the brain, giving rise to our initial experience
of the stimulus. An important idea to remember is that sensation involves converting
stimulation (such as a pinprick, a sound, or a flash of light) into a form the brain can
understand (neural signals)—much as a cell phone converts an electronic signal into
sound waves you can hear.
Psychologists who study sensation do so primarily from a biological perspective.
As you will see, they have found that all our sense organs are, in some very basic
ways, much alike. All the sense organs transform physical stimulation (such as light
waves or sound waves) into the neural impulses that give us sensations (such as the
experience of light or sound). In this chapter, you will also learn about the biological
and psychological bases for color, odor, sound, texture, and taste. By the end of our
excursion, you will know why tomatoes and limes have different hues, why a pinprick
feels different from a caress, and why seeing doesn’t always give us an accurate basis
for believing.
Happily, under most conditions, our sensory experience is highly reliable. So
when you catch sight of a friend, the sensation usually registers clearly, immediately,
sensation The process by which stimulation of
a sensory receptor produces neural impulses that the
brain interprets as a sound, a visual image, an odor, a
taste, a pain, or other sensory image. Sensation repre-
sents the first series of steps in processing of incoming
information.
Psychologists study sensation primarily
from a biological perspective.

How Does Stimulation Become Sensation? 89
and accurately. Yet, we humans do have our sensory limitations—just as
other creatures do. In fact, we lack the acute senses so remarkable in many
other species: the vision of hawks, the hearing of bats, the sense of smell of
rodents, or the sensitivity to magnetic fields found in migratory birds. So
do we humans excel at anything? Yes. Our species has evolved the sensory
equipment that enables us to process a wider range and variety of sensory
input than any other.
But sensation is only half the story. Our ultimate destination in this chap-
ter lies, beyond mere sensation, in the amazing realm of perception. There
we will uncover the psychological processes that attach meaning and per-
sonal significance to the sensory messages entering our brains. Perceptual
psychology will help you understand how we assemble a series of tones into
a familiar melody or a collage of shapes and shadings into a familiar face.
More generally, we will define perception as a mental process that elaborates
and assigns meaning to the incoming sensory patterns. Thus, perception cre-
ates an interpretation of sensation. Perception gives answers to such ques-
tions as: What do I see—a tomato? Is the sound I hear a church bell or a doorbell?
Does the face belong to someone I know? Until quite recently, the study of per-
ception was primarily the province of psychologists using the cognitive perspective.
Now that brain scans have opened new “windows” on perceptual processes in the
brain, neuroscientists have joined them in the quest to find biological explanations
for perception.
As you can see, the boundary of sensation blurs into that of perception. Percep-
tion is essentially an interpretation and elaboration of sensation. Seen in these terms,
sensation refers just to the initial steps in the processing of a stimulus. It is to these
first sensory steps that we now turn our attention.
3.1 KEY QUESTION
How Does Stimulation Become Sensation?
A thunderstorm is approaching, and you feel the electric charge in the air make the
hair stand up on your neck. Lightning flashes, and a split second later, you hear the
thunderclap. It was close by, and you smell the ozone left in the wake of the bolt as it
sizzled through the air. Your senses are warning you of danger.
Our senses have other adaptive functions, too. They aid our survival by direct-
ing us toward certain stimuli, such as tasty foods, which provide nourishment. Our
senses also help us locate mates, seek shelter, and recognize our friends. Incidentally,
our senses also give us the opportunity to find pleasure in music, art, athletics, food,
and sex.
How do our senses accomplish all this? The complete answer is complex, but it
involves one elegantly simple idea that applies across the sensory landscape: Our sen-
sory impressions of the world involve neural representations of stimuli—not the actual
stimuli themselves. The Core Concept puts it this way:
Core Concept 3.1
The brain senses the world indirectly because the sense organs
convert stimulation into the language of the nervous system: neural
messages.
The brain never receives stimulation directly from the outside world. Its experience
of a tomato is not the same as the tomato itself—although we usually assume that
the two are identical. Neither can the brain receive light from a sunset, reach out and
touch velvet, or inhale the fragrance of a rose. It must always rely on secondhand
perception A process that makes sensory patterns
meaningful. It is perception that makes these words
meaningful, rather than just a string of visual patterns.
To make this happen, perception draws heavily on
memory, motivation, emotion, and other psychological
processes.
Human senses do not detect the earth’s magnetic
fields that migratory birds use for navigation.
Until recently, psychologists studied
perception primarily from a cognitive
perspective.

90 C H A P T E R 3 Sensation and Perception
information from the go-between sensory system, which delivers only a coded neural
message, out of which the brain must create its own experience (see Figure 3.1). Just
as you cannot receive phone messages without a telephone receiver to convert the
electronic energy into sound you can hear, your brain also needs its sensory system to
convert the stimuli from the outside world into neural signals that it can comprehend.
To understand more deeply how the world’s stimulation becomes the brain’s sensa-
tion, we need to think about three attributes common to all the senses: transduction,
sensory adaptation, and thresholds. They determine which stimuli will actually be-
come sensation, what the quality and impact of that sensation will be, and whether it
grabs our interest. These attributes determine, for example, whether a tomato actually
registers in the sensory system strongly enough to enter our awareness, what its color
and form appear to be, and how strongly it bids for our attention.
Transduction: Changing Stimulation to Sensation
It may seem incredible that basic sensations, such as the redness and flavor of our
tomato—or the colors Jonathan could see before his accident—are entirely creations
of the sense organs and brain. But remember that all sensory communication with the
brain flows through neurons in the form of neural signals: Neurons cannot transmit
light or sound waves or any other external stimulus. Accordingly, none of the light
bouncing off the tomato ever actually reaches the brain. In fact, incoming light only
travels as far as the back of the eyes. There the information it contains is converted to
neural messages. Likewise, the chemicals that signal taste make their way only as far as
the tongue, not all the way to the brain.
In all the sense organs, it is the job of the sensory receptors, such as the eyes and
ears, to convert incoming stimulus information into electrochemical signals—neural
activity—the only language the brain understands. As Jonathan I.’s case suggests,
sensations, such as “red” or “sweet” or “cold,” occur only when the neural signal
reaches the cerebral cortex. The whole process seems so immediate and direct that
it fools us into assuming that the sensation of redness is characteristic of a tomato
or the sensation of cold is a characteristic of ice cream. But they are not! (You can
discover how light is not necessary for sensations of light with the demonstration in
the Do It Yourself! box, “Phosphenes Show That Your Brain Creates Sensations.”)
Psychologists use the term transduction for the sensory process that converts the
information carried by a physical stimulus, such as light or sound waves, into the form
of neural messages. Transduction begins when a sensory neuron detects a physical
stimulus (such as the sound wave made by a vibrating guitar string). When the appro-
priate stimulus reaches a sense organ, it activates specialized neurons, called receptors,
that respond by converting their excitation into a nerve signal. This happens in much
the same way that a bar-code reader (which is, after all, merely an electronic receptor)
converts the series of lines on a frozen pizza box into an electronic signal that a com-
puter can match with a price.
In our own sensory system, neural impulses carry the codes of sensory events in a
form that can be further processed by the brain. To get to its destination, this information-
carrying signal travels from the receptor cells along a sensory pathway—usually by way
transduction Transformation of one form of in-
formation into another—especially the transformation
of stimulus information into nerve signals by the sense
organs. As a result of transduction, the brain interprets
the incoming light waves from a ripe tomato as red.
FIGURE 3.1
Stimulation Becomes Perception
For visual stimulation to become mean-
ingful perception, it must undergo several
transformations. First, physical stimula-
tion (light waves from the butterfly) is
transduced by the eye, where informa-
tion about the wavelength and intensity
of the light is coded into neural signals.
Second, the neural messages travel to the
sensory cortex of the brain, where they
become sensations of color, brightness,
form, and movement. Finally, the process
of perception interprets these sensations
by making connections with memories,
expectations, emotions, and motives in
other parts of the brain. Similar processes
operate on the information taken in by
the other senses.
Stimulation Transduction Sensation
Neural signalsLight waves
Perception

How Does Stimulation Become Sensation? 91
of the thalamus and on to specialized sensory processing areas in the brain. From the
coded neural impulses arriving from these pathways, the brain then extracts information
about the basic qualities of the stimulus, such as its intensity and direction. Please keep
in mind, however, that the stimulus itself terminates in the receptor: The only thing that
flows into the nervous system is information carried by the neural impulse.
Let’s return now to the problem we set out at the beginning of the chapter: How
could we tell whether the world we “see” in our minds is the same as the external
world—and whether we see the world as others do? The idea of transduction gives us
part of the answer. Because we do not see (or hear, or smell . . .) the external world di-
rectly, what we sense is an electrochemical rendition of the world created by the sen-
sory receptors and the brain. To give an analogy: Just as digital photography changes
a scene first into electronic signals and then into drops of ink on a piece of paper, so
the process of sensation changes the world into a pattern of neural impulses realized
in the brain.
Thresholds: The Boundaries of Sensation
What is the weakest stimulus an organism can detect? How dim can a light be and still
be visible? How soft can music be and still be heard? These questions refer to the absolute
threshold for different types of stimulation, which is the minimum amount of physical
energy needed to produce a sensory experience. In the laboratory, a psychologist would
define this operationally as the intensity at which the stimulus is detected accurately half
of the time over many trials. This threshold will also vary from one person to another. So
if you point out a faint star to a friend who says he cannot see it, the star’s light is above
your absolute threshold (you can see it) but below that of your friend (who cannot).
A faint stimulus does not abruptly become detectable as its intensity increases. Be-
cause of the fuzzy boundary between detection and nondetection, a person’s absolute
threshold is not absolute! In fact, it varies continually with our mental alertness and
physical condition. Experiments designed to determine thresholds for various types of
stimulation were among the earliest studies done by psychologists—who called this
line of inquiry psychophysics. Table 3.1 shows some typical absolute threshold levels
for several familiar natural stimuli.
We can illustrate another kind of threshold with the following imaginary experi-
ment. Suppose you are relaxing by watching television on the one night you don’t need
absolute threshold The amount of stimulation
necessary for a stimulus to be detected. In practice,
this means that the presence or absence of a stimulus
is detected correctly half the time over many trials.
PHOSPHENES SHOW THAT YOUR BRAIN CREATES SENSATIONS
One of the simplest concepts in perceptual
psychology is among the most difficult for
most people to grasp: The brain and its
sensory systems create the colors, sounds,
tastes, odors, textures, and pains that you
sense. You can demonstrate this to yourself
in the following way.
Close your eyes and press gently with
your finger on the inside corner of one eye.
On the opposite side of your visual field, you
will “see” a pattern caused by the pressure of
your finger—not by light. These light sensa-
tions are phosphenes, visual images caused
by fooling your visual system with pressure,
which stimulates the optic nerve in much
the same way light does. Direct electrical
stimulation of the occipital lobe, sometimes
done during brain surgery, can have the same
effect. This shows that light waves are not
absolutely necessary for the sensation of light.
The sensory experience of light, therefore,
must be a creation of the brain rather than a
property of objects in the external world.
Phosphenes may have some practical
value, too. Several laboratories are work-
ing on ways to use phosphenes, created by
stimulation sent from a TV camera to the
occipital cortex to create visual sensations for
people who have lost their sight (Wickelgren,
2006). Another promising approach under
development involves replacing a section
of the retina with an electronic microchip
(Boahen, 2005; Liu et al., 2000). We hasten
to add, however, that this technology is in its
infancy (Cohen, 2002; U.S. Department of
Energy Office of Science, 2011).
sensation of light
C O N N E C T I O N CHAPTER 1
An operational definition describes
a concept in terms of the
operations required to produce,
observe, or measure it (p. 24).

92 C H A P T E R 3 Sensation and Perception
to study, while a roommate busily prepares for an early morning exam. Your room-
mate asks you to “turn it down a little” to eliminate the distraction. You feel that you
should make some effort to comply but really wish to leave the volume as it is. What
is the least amount you can lower the volume to prove your good intentions to your
roommate while still keeping the sound clearly audible? Your ability to make judg-
ments like this one depends on your difference threshold (also called the just noticeable
difference or JND), the smallest physical difference between two stimuli that a person
can reliably detect 50 percent of the time.
If you turn down the volume as little as possible, your roommate might complain,
“I don’t hear any difference.” By this, your roommate probably means that the change
in volume does not match his or her difference threshold. By gradually lowering the
volume until your roommate says “when,” you will be able to find the difference
threshold that keeps the peace in your relationship.
Investigation of the difference thresholds across the senses has yielded some inter-
esting insights into how human stimulus detection works. It turns out that the JND is
always large when the stimulus intensity is high and small when the stimulus intensity
is low. Psychologists refer to this idea—that the size of the JND is proportional to the
intensity of the stimulus—as Weber’s law. And what does Weber’s law tell us about ad-
justing the TV volume? If you have the volume turned up very high, you will have to
turn it down a lot to make the difference noticeable. On the other hand, if you already
have the volume set to a very low level, a small adjustment will probably be noticeable
enough for your roommate. The same principle operates across all our senses. Know-
ing this, you might guess that a weight lifter would notice the difference when small
amounts are added to light weights, but it would take a much larger addition to be
noticeable with heavy weights.
What does all this mean for our understanding of human sensation? The general
principle is this: We are built to detect changes in stimulation and relationships among
stimuli. You can see how this works in the box, Do It Yourself! An Enlightening Dem-
onstration of Sensory Relationships.
difference threshold The smallest amount by
which a stimulus can be changed and the difference be
detected half the time.
Weber’s law The concept that the size of a JND
is proportional to the intensity of the stimulus; the JND
is large when the stimulus intensity is high and small
when the stimulus intensity is low.
AN ENLIGHTENING DEMONSTRATION OF SENSORY RELATIONSHIPS
In this simple demonstration, you will see
how detection of change in brightness is
relative, not absolute. Find a three-way
lamp equipped with a bulb having equal
wattage increments, such as a 50-100-
150-watt bulb. (Wattage is closely related
to brightness.) Then, in a dark room, switch
the light on to 50 watts, which will seem
like a huge increase in brightness relative
to the dark. Next, turn the switch to change
from 50 to 100 watts: This will also seem
like a large increase—but not so much as it
did when you originally turned on the light
in the dark. Finally, switch from 100 to
150 watts. Why does this last 50-watt in-
crease, from 100 to 150 watts, appear only
slightly brighter?
Your visual system does not give you
an absolute sensation of brightness; rather,
it provides information about the relative
change. That is, it compares the stimulus
change to the background stimulation,
translating the jump from 100 to 150
watts as a mere 50 percent increase (50
watts added to 100) compared to the ear-
lier 100 percent increase (50 watts added
to 50). This illustrates how your visual
system computes sensory relationships
rather than absolutes—and it is essentially
the same with your other senses.
TABLE 3.1 Approximate Sensory Thresholds of Five Senses
Sense Detection Threshold
Sight A candle flame at 30 miles on a clear, dark night
Hearing The tick of a watch 20 feet away in a quiet room
Smell One drop of perfume diffused throughout a three-room apartment
Taste One teaspoon of sugar in 2 gallons of water
Touch A bee’s wing falling on the cheek from 1 centimeter above

How Does Stimulation Become Sensation? 93
Signal Detection Theory
A deeper understanding of absolute and difference thresholds comes from signal detec-
tion theory (Green & Swets, 1966). Originally developed for engineering electronic
sensors, signal detection theory uses the same concepts to explain both the electronic
sensing of stimuli by devices, such as your TV set, and by the human senses, such as
vision and hearing.
According to signal detection theory, sensation depends on the characteristics of the
stimulus, the background stimulation, and the detector. Thus, how well you receive a
stimulus, such as a professor’s lecture, depends on the presence of competing stimuli
in the background—the clacking keys of a nearby laptop or intrusive fantasies about a
classmate. It will also depend on the condition of your “detector”—your brain—and,
perhaps, whether it has been aroused by a strong cup of coffee or dulled by drugs or
lack of sleep.
Signal detection theory also helps us understand why thresholds vary—why, for
example, you might notice a certain sound one time and not the next. The clas-
sical theory of thresholds ignored the effects of the perceiver’s physical condition,
judgments, or biases. Thus, in classical psychophysics (as the study of stimulation,
thresholds, and sensory experience was called before signal-detection theory
came along), if a signal were intense enough to exceed one’s absolute thresh-
old, it would be sensed; if below the threshold, it would be missed. In the
view of modern signal detection theory, sensation is not a simple yes-or-no
experience but a probability that the signal will be detected and processed
accurately.
So, what does signal detection theory offer psychology that was missing
in classical psychophysics? One factor is the variability in human judgment.
Another involves the conditions in which the signal occurs. Signal detec-
tion theory recognizes that the observer, whose physical and mental status
is always in flux, must compare a sensory experience with ever-changing
expectations and biological conditions. When something “goes bump in the
night” after you have gone to bed, you must decide whether it is the cat,
an intruder, or just your imagination. But what you decide it is depends on
factors such as the keenness of your hearing and what you expect to hear, as well
as other noises in the background. By taking into account the variable conditions
that affect detection of a stimulus, signal detection theory provides a more accurate
portrayal of sensation than did classical psychophysics.
PSYCHOLOGY MATTERS
Sensory Adaptation
If you have ever jumped into a cool pool on a hot day, you know that sensation is criti-
cally influenced by change. In fact, a main role of our stimulus detectors is to announce
changes in the external world—a flash of light, a splash of water, a clap of thunder,
the approach of a lion, the prick of a pin, or the burst of flavor from a dollop of salsa.
Thus, our sense organs are change detectors. Their receptors specialize in gathering
information about new and changing events.
The great quantity of incoming sensation would quickly overwhelm us, if not for
the ability of our sensory systems to adapt. Sensory adaptation is the diminishing re-
sponsiveness of sensory systems to prolonged stimulation, as when you adapt to the
feel of swimming in cool water. In fact, any unchanging stimulation usually shifts into
the background of our awareness unless it is quite intense or painful. On the other
hand, any change in stimulation (as when a doorbell rings) will immediately draw
your attention.
Incidentally, sensory adaptation accounts for the background music often played
in stores being so forgettable: It has been deliberately selected and filtered to remove
signal detection theory Explains how we de-
tect “signals,” consisting of stimulation affecting our
eyes, ears, nose, skin, and other sense organs. Signal
detection theory says that sensation is a judgment the
sensory system makes about incoming stimulation.
Often, it occurs outside of consciousness. In contrast
to older theories from psychophysics, signal detection
theory takes observer characteristics into account.
sensory adaptation Loss of responsiveness
in receptor cells after stimulation has remained
unchanged for a while, as when a swimmer becomes
adapted to the temperature of the water.
Signal detection theory says that the
background stimulation would make it
less likely for you to hear someone call-
ing your name on a busy downtown street
than in a quiet park.

94 C H A P T E R 3 Sensation and Perception
3.2 KEY QUESTION
How Are the Senses Alike? How Are They Different?
Vision, hearing, smell, taste, touch, pain, body position: In certain ways, all these
senses are the same. We have seen that they all transduce stimulus energy into neural
impulses. They are all more sensitive to change than to constant stimulation. And they
all provide us information about the world—information that has survival value. But
how are they different? With the exception of pain, each sense taps a different form of
stimulus energy, and each sends the information it extracts to a different part of the
brain. These contrasting ideas lead us to the Core Concept of this section:
Core Concept 3.2
The senses all operate in much the same way, but each extracts
different information and sends it to its own specialized processing
region in the brain.
As a result, different sensations occur because different areas of the brain become
activated. Whether you hear a bell or see a bell depends ultimately on which part of the brain
receives stimulation. We will explore how this all works by looking at each of the senses
in turn. First, we will explore the visual system—the best understood of the senses—to
discover how it transduces light waves into visual sensations of color and brightness.
Vision: How the Nervous System Processes Light
Animals with good vision have an enormous biological advantage. This fact has
exerted evolutionary pressure to make vision the most complex, best-developed, and
important sense for humans and most other highly mobile creatures. Good vision helps
us detect desired targets, threats, and changes in our physical environment and to
adapt our behavior accordingly. So, how does the visual system accomplish this?
any large changes in volume or pitch that might distract attention from the mer-
chandise. (On the other hand, do you see why it’s not a good idea to listen to your
favorite music while studying?)
Check Your Understanding
1. RECALL: The sensory pathways carry information from
to .
2. RECALL: Why do sensory psychologists use the standard of the
amount of stimulation that your sensory system can detect about
half the time for identifying the absolute threshold?
3. APPLICATION: Which one would involve sensory adaptation?
a. The odor of food cooking is more noticeable when you enter the
house than after you have been there a while.
b. The flavor of a spicy salsa on your taco seems hot by comparison
with the blandness of the sour cream.
c. You are unaware of a stimulus flashed on the screen at 1/100 of
a second.
d. You prefer the feel of silk to the feel of velvet.
4. RECALL: What is the psychological process that adds meaning to
information obtained by the sensory system?
5. UNDERSTANDING THE CORE CONCEPT: Use the concept
of transduction to explain why the brain never directly senses the
outside world.
Answers 1. The sense organs; the brain. 2. The amount of stimulation that we can detect is not fixed. Rather, it varies depending on ever-changing
factors such as our level of arousal, distractions, fatigue, and motivation. 3. a 4. Perception 5. The senses transduce stimulation from the external
world into the form of neural impulses, which is the only form of information that the brain can use. Therefore, the brain does not deal directly with
light, sound, odors, and other stimuli but only with information that has been changed (transduced) into neural messages.
Study and Review at MyPsychLab

How Are the Senses Alike? How Are They Different? 95
The Anatomy of Visual Sensation You might think of the eye as a sort of “video
camera” that the brain uses to make motion pictures of the world (see Figure 3.2). Like
a camera, the eye gathers light through a lens, focuses it, and forms an image in the ret-
ina at the back of the eye. The lens, incidentally, turns the image left to right and upside
down. (Because vision is so important, this visual reversal may have influenced the very
structure of the brain, which, you will remember, tends to maintain this reversal in its
sensory processing regions. Thus, most information from the sense organs crosses over
to the opposite side of the brain. Likewise, “maps” of the body in the brain’s sensory
areas are typically reversed and inverted.)
But while a digital camera simply forms an electronic image, the eye forms an image
that gets extensive further processing in the brain. The unique characteristic of the
eye—what makes the eye different from other sense organs—lies in its ability to extract
the information from light waves, which are simply a form of electromagnetic energy.
The eye, then, transduces the characteristics of light into neural signals that the brain
can process. This transduction happens in the retina, the light-sensitive layer of cells at
the back of the eye that acts much like the light-sensitive chip in a digital camera.
And, as with a camera, things can go wrong. For example, the lenses of those who
are “nearsighted” focus images short of (in front of) the retina; in those who are “far-
sighted,” the focal point extends behind the retina. Either way, images are not sharp
without corrective lenses.
The real work in the retina is performed by light-sensitive cells known as photo-
receptors, which operate much like the tiny pixel receptors in a digital camera. These
photoreceptors consist of two different types of specialized neurons—the rods and
cones that absorb light energy and respond by creating neural impulses (see Figure 3.3).
But why are there two sorts of photoreceptors?
Because we function sometimes in near darkness and sometimes in bright light, we
have evolved two types of processors involving two distinct receptor cell types named
for their shapes. The 125 million tiny rods “see in the dark”—that is, they detect low
retina The thin light-sensitive layer at the back of
the eyeball. The retina contains millions of photorecep-
tors and other nerve cells.
photoreceptors Light-sensitive cells (neurons) in
the retina that convert light energy to neural impulses.
The photoreceptors are as far as light gets into the
visual system.
rods Photoreceptors in the retina that are especially
sensitive to dim light but not to colors. Strange as it
may seem, they are rod-shaped.
Fluid (aqueous humor)
Muscle
(for focusing lens) Optic nerve
Blood vessels
Blind spot
Fovea
Retina
Fluid (vitreous humor)
Muscle (for turning eye)
Iris
Lens
Pupil
Cornea
FIGURE 3.2
Structures of the Human Eye

96 C H A P T E R 3 Sensation and Perception
intensities of light at night, though they cannot make the fine distinctions that give
rise to our sensations of color. Rod cells enable you to find a seat in a darkened movie
theater.
Making the fine distinctions necessary for color vision is the job of the seven mil-
lion cones that come into play in brighter light. Each cone is specialized to detect the
light waves we sense either as blue, red, or green. In good light, then, we can use these
cones to distinguish ripe tomatoes (sensed as red) from unripe ones (sensed as green).
The cones concentrate in the very center of the retina, in a small region called the fovea,
which gives us our sharpest vision. With movements of our eyeballs, we use the fovea
to scan whatever interests us visually—the features of a face or, perhaps, a flower.
There are other types of cells in the retina that do not respond directly to light. The
bipolar cells handle the job of collecting impulses from many photoreceptors (rods and
cones) and shuttling them on to the ganglion cells, much as an airline hub collects pas-
sengers from many regional airports and shuttles them on to other destinations. The
retina also contains receptor cells sensitive to edges and boundaries of objects; other
cells respond to light and shadow and motion (Werblin & Roska, 2007).
Bundled together, the axons of the ganglion cells make up the optic nerve, which
transports visual information from the eye to the brain (refer to Figures 3.2 and 3.3).
Again, it is important to understand that the optic nerve carries no light—only patterns
of nerve impulses conveying information derived from the incoming light.
Just as strangely, there is a small area of the retina in each eye where everyone is
blind, because that part of the retina has no photoreceptors. This blind spot is located
at the point where the optic nerve exits each eye, and the result is a gap in the visual
field. You do not experience blindness there because what one eye misses is registered
by the other eye, and the brain “fills in” the spot with information that matches the
background. You can find your own blind spot by following the instructions in the Do
It Yourself! box.
We should clarify that the visual impairment we call blindness can have many
causes, which are usually unrelated to the blind spot. Blindness can result, for example,
from damage to the retina, cataracts that make the lens opaque, damage to the optic
nerve, or from damage to the visual processing areas in the brain.
cones Photoreceptors in the retina that are
especially sensitive to colors but not to dim light. You
may have guessed that the cones are cone-shaped.
fovea The tiny area of sharpest vision in the retina.
optic nerve The bundle of neurons that carries
visual information from the retina to the brain.
blind spot The point where the optic nerve exits
the eye and where there are no photoreceptors. Any
stimulus that falls on this area cannot be seen.
FIGURE 3.3
Transduction of Light in the Retina
This simplified diagram shows the path-
ways that connect three layers of nerve
cells in the retina. Incoming light passes
through the ganglion cells and bipolar
cells first before striking the photorecep-
tors at the back of the eyeball. Once stim-
ulated, the rods and cones then transmit
information to the bipolar cells (note that
one bipolar cell combines information
from several receptor cells). The bipolar
cells then transmit neural impulses to the
ganglion cells. Impulses travel from the
ganglia to the brain via axons that make
up the optic nerve.
Ba
ck
o
f r
et
in
a
Eyeball
Area enlarged
Optic nerve
Outgoing nerve
impulse to cortex
Rod and cone cells
Gan
glio
n
cell
s
Bip
ola
r
cell
s
Incoming
light stimulus

How Are the Senses Alike? How Are They Different? 97
Processing Visual Sensation in the Brain We look with our eyes, but we see with
the brain. That is, a special brain area called the visual cortex creates visual images
from the information imported from the eyes through the optic nerve (see Figure
3.4). There in the visual cortex, the brain begins working its magic by transforming
the incoming neural impulses into visual sensations of color, form, boundary, and
FIND YOUR BLIND SPOT
The “blind spot” occurs at the place on the
retina where the neurons from the retina
bunch together to exit the eyeball and form
the optic nerve. There are no light-sensitive
cells at this point on the retina. Conse-
quently, you are “blind” in this small region
of your visual field. The following demon-
strations will help you determine where this
blind spot occurs in your visual field.
Demonstration 1
Hold the text at arm’s length, close your
right eye, and fix your left eye on the
“bank” figure. Keep your right eye closed
and bring the book slowly closer. When
it is about 10 to 12 inches away and the
dollar sign is in your blind spot, the dollar
sign will disappear—but you will not see a
“hole” in your visual field. Instead, your vi-
sual system “fills in” the missing area with
information from the white background. You
have “lost” your money!
Demonstration 2
To convince yourself that the brain fills in
the missing part of the visual field with ap-
propriate background, close your right eye
again and focus on the cross in the lower
part of the figure. Once again, keeping the
right eye closed, bring the book closer to you
as you focus your left eye on the cross. This
time, the gap in the line will disappear and
will be filled in with a continuation of the
line on either side. This shows that what you
see in your blind spot may not really exist!
Bank
$
FIGURE 3.4
How Visual Stimulation Goes
from the Eyes to the Brain
Light from objects in the visual field
projects images on the retinas of the
eyes. Please note two important things.
First, the lens of the eye reverses the
image on the retina—so the image of the
man falls on the right side of the retina,
and the image of the woman falls on the
left. Second, the visual system splits the
retinal image coming from each eye so
that part of the image coming from each
eye crosses over to the opposite side of
the brain. (Note how branches of the op-
tic pathway cross at the optic chiasma.)
As a result, objects appearing in the left
part of the visual field of both eyes (the
man, in this diagram) are sent to the right
hemisphere’s visual cortex for process-
ing, while objects in the right side of the
visual field of both eyes (the woman, in
this diagram) are sent to the left visual
cortex. In general, the right hemisphere
“sees” the left visual field, while the left
hemisphere “sees” the right visual field.
Source: Frisby, J. P. (1980). Seeing: Illusion, brain
and mind. New York: Oxford University Press.
Copyright © 1979. Reprinted by permission of
J. P. Frisby.
Retinal image
Left eye Right eye
Optic nerve
(from eye to brain)
Optic chiasma
Lateral geniculate
nucleus (left)
Visual
association
cortex
Primary visual cortex
Optic tract

98 C H A P T E R 3 Sensation and Perception
movement. Amazingly, the visual cortex also manages to take the two-dimensional
patterns from each eye and assemble them into our three- dimensional world of depth
(Barinaga, 1998; Dobbins et al., 1998). With further processing, the cortex ultimately
combines these visual sensations with memories, motives, emotions, and sensations
of body position and touch to create a representation of the visual world that fits our
current concerns and interests (de Gelder, 2000; Vuilleumier & Huang, 2009). These
associations explain why, for example, you feel so strongly attracted by displays of
appetizing foods if you go grocery shopping when you are hungry.
Let’s return for a moment to the chapter problem and to the question, Do we
“see” the world as others do? As far as sensation is concerned, we will find that
the answer is a qualified “yes.” That is, different people have essentially the same
sensory apparatus (with the exceptions of a few individuals who, like Jonathan,
cannot distinguish colors or who have other sensory deficits). Therefore, it is rea-
sonable to assume that most people sense colors, sounds, textures, odors, and tastes
in much the same way—although, as we will see, they do not necessarily perceive
them in the same way. To see what we mean, let’s start with the visual sensation of
brightness.
How the Visual System Creates Brightness Sensations of brightness come from the intensity
or amplitude of light, determined by how much light reaches the retina (see Table 3.2).
Bright light, as from the sun, involves a more intense light wave, which creates much
neural activity in the retina, while relatively dim light, as from the moon, produces rela-
tively little retinal activity. Ultimately, the brain senses brightness by the volume of neural
activity it receives from the eyes.
How the Visual System Creates Color You may have been surprised to learn that a flower
or a ripe tomato, itself, has no color, or hue. Physical objects seen in bright light seem
to have the marvelous property of being awash with color; but, as we have noted, the
red tomatoes, yellow flowers, green trees, blue oceans, and multihued rainbows are, in
themselves, actually quite colorless. Nor does the light reflected from these objects have
color. Despite the way the world appears to us, color does not exist outside the brain
because color is a sensation that the brain creates based on the wavelength of light
striking our eyes. Thus, color exists only in the mind of the viewer—a psychological
property of our sensory experience. To understand more fully how this happens, you
must first know something of the nature of light.
The eyes detect the special form of energy that we call visible light. Physicists tell us
that this light is pure energy—fundamentally the same as radio waves, microwaves, infra-
red light, ultraviolet light, X-rays, and cosmic rays. All are forms of electromagnetic energy.
These waves differ in their wavelength (the distance they travel in making one wave cycle)
as they vibrate in space, like ripples on a pond (see Figure 3.5). The light we see occupies
but a tiny segment somewhere near the middle of the vast electromagnetic spectrum. Our
only access to this electromagnetic spectrum lies through a small visual “window” called
the visible spectrum. Because we have no biological receptors sensitive to the other portions
of the electromagnetic spectrum, we must detect these waves through devices, such as ra-
dios and TVs, that convert the energy into signals we can use.
C O N N E C T I O N CHAPTER 2
Note that part of the visual
pathway of each eye crosses over
to the cortex on the opposite side
of the brain. This produced some
of the bizarre responses that we
saw in the tests of split-brain
patients (p. 75).
brightness A psychological sensation caused by
the intensity (amplitude) of light waves.
color Also called hue. Color is not a property of
things in the external world. Rather, it is a psychologi-
cal sensation created in the brain from information ob-
tained by the eyes from the wavelengths of visible light.
electromagnetic spectrum The entire range
of electromagnetic energy, including radio waves,
X-rays, microwaves, and visible light.
visible spectrum The tiny part of the electro-
magnetic spectrum to which our eyes are sensitive.
The visible spectrum of other creatures may be slightly
different from our own.
TABLE 3.2 Visual Stimulation Becomes Sensation
Color and brightness are the psychological counterparts of the
wavelength and intensity of a light wave. Wavelength and intensity
are physical characteristics of light waves, while color and brightness
are psychological characteristics that exist only in the brain.
Physical Stimulation Psychological Sensation
Wavelength Color
Intensity (amplitude) Brightness

How Are the Senses Alike? How Are They Different? 99
Within the narrow visible spectrum, light waves of different wavelengths give rise
to our sensations of different colors. Longer waves make us see a tomato as red, and
medium-length waves give rise to the sensations of yellow and green we see in lem-
ons and limes. The shorter waves from a clear sky stimulate sensations of blue. Thus,
the eye extracts information from the wavelength of light, and the brain uses that
information to construct the sensations we see as colors (see Table 3.2).
Remarkably, our visual experiences of color, form, position, and depth are based
on processing the stream of visual sensory information in different parts of the cor-
tex. Colors themselves are realized in a specialized area, where humans are capable
of discriminating among about five million different hues. It was damage in this
part of the cortex that shut down Jonathan’s ability to see colors. Other nearby cor-
tical areas take responsibility for processing information about boundaries, shapes,
and movements.
Two Ways of Sensing Colors Even though color is realized in the cortex, color
processing begins in the retina. There, three different types of cones sense dif-
ferent parts of the visible spectrum—light waves that we sense as red, green,
and blue. This three-receptor explanation for color vision is known as the
trichromatic theory, and for a time it was considered to account for color vision
completely. We now know that the trichromatic theory best explains the initial
stages of color vision in the cone cells.
Another explanation, called the opponent-process theory, better explains
negative afterimages (see the Do It Yourself! box), phenomena that involve
opponent, or complementary, colors. According to the opponent-process the-
ory, the visual system processes colors, from the bipolar cells onward, in com-
plementary pairs: red-green or yellow-blue. Thus, the sensation of a certain
color, such as red, inhibits, or interferes with, the sensation of its complement,
green. Taken together, the two theories explain two different aspects of color
vision involving the retina and visual pathways. While all that may sound
complicated, here is the take-home message: The trichromatic theory explains
color processing in the cones of the retina, while the opponent-process theory
explains what happens in the bipolar cells and beyond.
Color Blindness Not everyone sees colors in the same way, because some people
are born with a deficiency in distinguishing colors. The incidence varies among
trichromatic theory The idea that colors are
sensed by three different types of cones sensitive to
light in the red, blue, and green wavelengths. The
trichromatic (three-color) theory explains the earliest
stage of color sensation. In honor of its originators, this
is sometimes called the Young-Helmholtz theory.
opponent-process theory The idea that cells
in the visual system process colors in complementary
pairs, such as red or green or as yellow or blue. The
opponent-process theory explains color sensation from
the bipolar cells onward in the visual system.
afterimages Sensations that linger after the stim-
ulus is removed. Most visual afterimages are negative
afterimages, which appear in reversed colors.
The combination of any two primary colors of light
yields the complement of a third color. The com-
bination of all three wavelengths produces white
light. (The mixture of pigments, as in print, works
differently, because pigments are made to absorb
some wavelengths of light falling on them.)
FIGURE 3.5
The Electromagnetic Spectrum
The only difference between visible light
and other forms of electromagnetic en-
ergy is wavelength. The receptors in our
eyes are sensitive to only a tiny portion of
the electromagnetic spectrum.
Source: Sekuler, R., & Blake, R. (1994). Perception,
3rd ed. New York: McGraw-Hill. Copyright © 1994.
Reprinted by permission of McGraw-Hill.
Gamma
rays
Visible
light
X rays
Violet
400 500 600 700
Blue Green
Wavelength in nanometers
shorter
wavelengths
short long
longer
wavelengths
Yellow Red
Ultra-
violet
rays
Infra-
red
rays
Radar FM
radio
AM
radio
AC
circuits
Micro-
waves
TV
10-3 10-1 101 103 105 107 109 1011 1013 1015

100 C H A P T E R 3 Sensation and Perception
racial groups (highest in Whites and lowest in Blacks). Overall about 8 percent of males
in the United States are affected. Women rarely have the condition.
At the extreme, complete color blindness is the total inability to distinguish col-
ors. More commonly, people merely have a color weakness that causes minor prob-
lems in distinguishing colors, especially under low-light conditions. People with one
form of color weakness can’t distinguish pale colors, such as pink or tan. Most
color weakness or blindness, however, involves a problem in distinguishing red
from green, especially at weak saturations. Those who confuse yellows and blues
are rare, about one or two people per thousand. Rarest of all are those who see no
color at all but see only variations in brightness. In fact, only about 500 cases of
this total color blindness have ever been reported—including Jonathan I., whom we
met at the beginning of this chapter. To find out whether you have a deficiency in
color vision, look at Figure 3.6. If you see the number 29 in the dot pattern, your
color vision is probably normal. If you see something else, you are probably at least
partially color blind.
Hearing: If a Tree Falls in the Forest . . .
Imagine how your world would change if your ability to hear were suddenly dimin-
ished. You would quickly realize that hearing, like vision, provides you with the abil-
ity to locate objects in space, such as the source of a voice calling your name. In fact,
hearing may be even more important than vision in orienting us toward distant events.
We often hear things, such as footsteps coming up behind us, before we see the source
of the sounds. Hearing may also tell us of events that we cannot see, including speech,
music, or an approaching car.
But there is more to hearing than its function. Accordingly, we will look a little
deeper to learn how we hear. In the next few pages, we will review what sensory psy-
chologists have discovered about how sound waves are produced, how they are sensed,
and how these sensations of sound are interpreted.
The Physics of Sound: How Sound Waves Are Produced If Hollywood gave us
an honest portrayal of exploding spaceships or planets, there would be absolutely no
sound! In space, there is no air or other medium to carry sound waves, so if you were a
witness to an exploding star, the experience would be eerily silent. On Earth, the energy
of exploding objects, such as firecrackers, transfers to the surrounding medium—usually
color blindness Typically a genetic disorder
(although sometimes the result of trauma, as in the
case of Jonathan) that prevents an individual from
discriminating certain colors. The most common form is
red–green color blindness.
THE AMAZING AFTERIMAGE
After you stare at a colored object for a
while, ganglion cells in your retina will
become fatigued, causing an interesting
visual effect. When you shift your gaze to a
blank, white surface, you can “see” the ob-
ject in complementary colors—as a visual
afterimage. The “phantom flag” demonstra-
tion will show you how this works.
Stare at the dot in the center of the
green, black, and orange flag for at least
30 seconds. Take care to hold your eyes
steady and not to let them scan over the
image during this time. Then quickly shift
your gaze to the center of a sheet of white
paper or to a light-colored blank wall. What
do you see? Have your friends try this,
too. Do they see the same afterimage?
(The effect may not be the same for
people who are color blind.)
Afterimages may be negative
or positive. Positive afterimages
are caused by a continuation of the
receptor and neural processes fol-
lowing stimulation. They are brief.
An example of positive afterimages
occurs when you see the trail of a
sparkler twirled by a Fourth of July
reveler. Negative afterimages are the
opposite or the reverse of the origi-
nal experience, as in the flag exam-
ple. They last longer. Negative afterimages
operate according to the opponent-process
theory of color vision, which involves
ganglion cells in the retina and the optic
nerve. Apparently, in a negative afterim-
age, the fatigue in these cells produces
sensations of a complementary color when
they are exposed to white light.
FIGURE 3.6
The Ishihara Color Blindness Test
Someone who cannot discriminate be-
tween red and green hues will not be
able to identify the number hidden in the
figure. What do you see? If you see the
number 29 in the dot pattern, your color
vision is probably normal.

How Are the Senses Alike? How Are They Different? 101
air—in the form of sound waves. Essentially the same thing happens with rapidly vi-
brating objects, such as guitar strings, bells, and vocal cords, as the vibrations push the
molecules of air back and forth. The resulting changes in pressure spread outward in
the form of sound waves that can travel 1,100 feet per second.
The purest tones are made by a tuning fork (see Figure 3.7). When struck with
a mallet, a tuning fork produces an extremely clean sound wave that has only two
characteristics, frequency and amplitude. These are the two physical properties of any
sound wave that determine how it will be sensed by the brain. Frequency refers to the
number of vibrations or cycles the wave completes in a given amount of time, which
in turn determines the highness or lowness of a sound (the pitch). Frequency is usually
expressed in cycles per second (cps) or hertz (Hz). Amplitude measures the physical
strength of the sound wave (shown in graphs as the height of the wave); it is defined
in units of sound pressure or energy. When you turn down the volume on your music
system, you are decreasing the amplitude of the sound waves emerging from the speak-
ers or ear buds.
Sensing Sounds: How We Hear Sound Waves Much like vision, the psychological
sensation of sound requires that waves be transduced into neural impulses and sent to
the brain. This happens in four steps:
1. Airborne sound waves are relayed to the inner ear. In this initial transformation,
vibrating waves of air enter the outer ear (also called the pinna) and move
through the ear canal to the eardrum, or tympanic membrane (see Figure 3.8). This
tightly stretched sheet of tissue transmits the vibrations to three tiny bones in the
frequency The number of cycles completed by a
wave in a second.
amplitude The physical strength of a wave. This is
shown on graphs as the height of the wave.
tympanic membrane The eardrum.
FIGURE 3.7
Sound Waves
Sound waves produced by the vibration of
a tuning fork create waves of compressed
and expanded air. The pitch that we hear
depends on the frequency of the wave
(the number of cycles per second). High
pitches are the result of high-frequency
waves. The amplitude or strength of a
sound wave depends on how strongly the
air is affected by the vibrations. In this
diagram, amplitude is represented by the
height of the graph.
One cycle
Time
A
m
pl
it
ud
e
ExpansionAir: Compression
FIGURE 3.8
Structures of the Human Ear
Sound waves are channeled by the outer
ear (pinna) through the external canal,
causing the tympanic membrane to vibrate.
The vibration activates the tiny bones in
the middle ear (hammer, anvil, and stir-
rup). These mechanical vibrations pass
from the oval window to the cochlea, where
they set an internal fluid in motion. The
fluid movement stimulates tiny hair cells
along the basilar membrane, inside the co-
chlea, to transmit neural impulses from the
ear to the brain along the auditory nerve.
Hammer
Stirrup
Oval windowAnvil
Semicircular
canals
Bones of the
middle ear
Cochlea
Basilar membrane
with vibration-
sensitive hair cells
Eardrum
Auditory
nerve

102 C H A P T E R 3 Sensation and Perception
middle ear: the hammer, anvil, and stirrup, named for their shapes. These bones
pass the vibrations on to the primary organ of hearing, the cochlea, located in the
inner ear.
2. The cochlea focuses the vibrations on the basilar membrane. Here in the cochlea, the
formerly airborne sound wave becomes “seaborne,” because the coiled tube of the
cochlea is filled with fluid. As the bony stirrup vibrates against the oval window
at the base of the cochlea, the vibrations set the fluid into wave motion, much as
a submarine sends a sonar “ping” through the water. As the fluid wave spreads
through the cochlea, it causes vibration in the basilar membrane, a thin strip of
hairy tissue running through the cochlea.
3. The basilar membrane converts the vibrations into neural messages. The swaying of tiny
hair cells on the vibrating basilar membrane stimulates sensory nerve endings con-
nected to the hair cells. The excited neurons, then, transform the mechanical vibra-
tions of the basilar membrane into neural activity.
4. Finally, the neural messages travel to the auditory cortex in the brain. Neural signals
leave the cochlea in a bundle of neurons called the auditory nerve. The neurons
from the two ears meet in the brain stem, which passes the auditory information
to both sides of the brain. Ultimately, the signals arrive in the auditory cortex for
higher-order processing.
If the auditory system seems complicated, you might think of it as a sensory “relay team.”
Sound waves are first funneled in by the outer ear, then handed off from the eardrum to
bones in the middle ear. These bones then hand off their mechanical vibrations to the
cochlea and basilar membrane in the inner ear, where they finally become neural signals,
which are, in turn, passed along to the brain. This series of steps transforms common-
place vibrations into experiences as exquisite and varied as music, doorbells, whispers,
and shouts—and psychology lectures.
Psychological Qualities of Sound: How We Distinguish One Sound from
Another No matter where they come from, sound waves—like light waves—have
only two physical characteristics: frequency and amplitude. In the following discus-
sion, we will show you how the brain converts these two characteristics into three
psychological sensations: pitch, loudness, and timbre.
Sensations of Pitch A sound wave’s frequency determines the highness or lowness of a
sound—a quality known as pitch. High frequencies produce high-pitched sounds, and
low frequencies produce low-pitched sounds, as you see in Table 3.3. As with light, our
sensitivity to sound spans only a limited range of the sound waves that occur in na-
ture. The range of human auditory sensitivity extends from frequencies as low as about
20 cps (the lowest range of a subwoofer in a good sound system) to frequencies as high
cochlea The primary organ of hearing; a coiled
tube in the inner ear, where sound waves are
transduced into nerve messages.
basilar membrane A thin strip of tissue sensi-
tive to vibrations in the cochlea. The basilar membrane
contains hair cells connected to neurons. When a sound
wave causes the hair cells to vibrate, the associated
neurons become excited. As a result, the sound waves
are converted (transduced) into nerve activity.
C O N N E C T I O N CHAPTER 2
The brain’s primary auditory
cortex lies in the temporal lobes
(p. 72).
pitch A sensory characteristic of sound produced by
the frequency of the sound wave.
TABLE 3.3 Auditory Stimulation
Becomes Sensation
Pitch and loudness are the psychological
counterparts of the frequency and
amplitude (intensity) of a sound
wave. Frequency and amplitude are
characteristics of the physical sound
wave, while sensations of pitch and
loudness exist only in the brain. In
addition, sound waves can be complex
combinations of simpler waves.
Psychologically, we experience this
complexity as timbre. Compare this table
with Table 3.2 for vision.
Loud
Low
Pure
Soft
High
Complex
Physical stimulation Waveform Psychological sensation
Amplitude (intensity) Loudness
Frequency (wavelength) Pitch
Complexity Timbre

How Are the Senses Alike? How Are They Different? 103
as 20,000 cps (produced by the high-frequency tweeter in a high-quality audio system).
Other creatures can hear sounds both higher (dogs, for example) and lower (elephants).
How does the auditory apparatus produce sensations of pitch? Two distinct audi-
tory processes share the task, affording us much greater sensory precision than either
could provide alone. Here’s what happens:
• When sound waves pass through the inner ear, the basilar membrane vibrates (see
Figure 3.8). Different frequencies activate different locations on the membrane.
Thus, the pitch one hears depends, in part, on which region of the basilar mem-
brane is receiving the greatest stimulation. This place theory explanation of pitch
perception says that different places on the basilar membrane send neural codes
for different pitches to the auditory cortex of the brain—much as keys in different
places on a piano keyboard can produce different notes. It turns out that the place
theory accounts for our ability to hear high tones—above about 1,000 Hz (cycles
per second).
• Neurons on the basilar membrane respond with different firing rates to different
sound wave frequencies, much as guitar strings vibrating at different frequencies
produce different notes. And so, the rate of firing provides another code for pitch
perception in the brain. This frequency theory explains how the basilar membrane
deals with frequencies below about 5,000 Hz.
• Between 1,000 and 5,000 Hz, hearing relies on both place and frequency.
What is so special about the range of 1,000 to 5,000 Hz? This interval spans the
upper frequency range of human speech, which is crucial for discriminating the high-
pitched sounds that distinguish consonants, such as p, s, and t. These are the subtle
sounds that allow us to distinguish among many common words, such as pie, sigh, and
tie. Coincidentally, the auditory canal is specially shaped to amplify sounds within this
speech range.
Sensations of Loudness Much as the intensity of light determines brightness, the physi-
cal strength or amplitude of a sound wave determines loudness, as shown in Table 3.3.
More intense sound waves (a shout) produce louder sounds, while we experience sound
waves with small amplitudes (a whisper) as soft. Amplitude, then, refers to the physical
characteristics of a sound wave, while loudness is a psychological sensation.
Because we can hear sound waves across a great range of intensity, the loudness of
a sound is usually expressed as a ratio rather than an absolute amount. More specifi-
cally, sound intensity is expressed in units called decibels (dB). Figure 3.9 shows the
levels of some representative natural sounds in decibel units.
Sensations of Timbre The bark of a dog, a toot of a train whistle, the wail of an oboe,
the clink of a spoon in a cup—all sound distinctively different, not just because they
have different pitches or loudness but because they are peculiar mixtures of tones.
In fact, most natural sound waves are mixtures rather than pure tones, as shown in
Figure 3.10. This complex quality of a sound wave is known as timbre (pronounced
TAM—b’r). Timbre is the property that enables you to recognize a friend’s voice on the
phone or distinguish between the same song sung by different artists.
Hearing Loss Aging commonly involves loss of hearing acuity, especially for high-
frequency sounds so crucial for understanding speech. If you think about the tiny dif-
ference between the sounds b and p, you can see why speech perception depends so
heavily on high frequency sounds. But hearing loss is not always the result of aging. It
can come from diseases, such as mumps, that may attack the auditory nerves. And it
can result from exposure to loud noises (see Figure 3.9), such as gunshots, jet engines,
or loud music, that damage the hair cells in the cochlea.
How Are Auditory and Visual Sensations Alike? Earlier, we discussed how visual
information is carried to the brain by the optic nerve in the form of neural impulses.
Now we find that, in a similar fashion, auditory information is also conveyed to the
loudness A sensory characteristic of sound pro-
duced by the amplitude (intensity) of the sound wave.
timbre The quality of a sound wave that derives
from the wave’s complexity (combination of pure tones).
Timbre comes from the Greek word for “drum,” as does
the term tympanic membrane, or eardrum.
dB
Decibel
level
180
140
130
120
100
80
60
40
20
0
Rocket launch
(from 150 ft)
Jet plane take off
(from 80 ft)
Threshold of pain
Loud thunder; rock band
Twin-engine airplane
take off
Inside subway train
Hearing loss with
prolonged exposure
Inside noisy car
Inside quiet car
Normal conversation
Normal office
Quiet office
Quiet room
Soft whisper (5 ft)
Absolute hearing
threshold
(for 1000-Hz tone)
FIGURE 3.9
Intensities of Familiar Sounds
Cochlear ImplantsWatch the Video
at MyPsychLab

104 C H A P T E R 3 Sensation and Perception
brain as neural signals—but by a different pathway and to a different location in
the brain. Please note the similarity in the ways vision and hearing make use of fre-
quency and amplitude information found in light and sound waves.
But why do we “see” visual information and “hear” auditory information? As our
Core Concept suggested, the answer lies in the region of the cortex receiving the neural
message—not on some unique quality of the message itself. In brief, different regions
of the brain, when activated, produce different sensations.
How the Other Senses Are Like Vision and Hearing
Of all our senses, vision and hearing have been studied the most. However, our sur-
vival and well-being depend on other senses, too. So, to conclude this discussion of
sensation, we will briefly review the processes involved in our sense of body position
and movement, smell, taste, the skin senses, and pain (see Table 3.4). You will note
that each gives us information about a different aspect of our internal or external en-
vironment. Yet each operates on similar principles. Each transduces physical stimuli
into neural activity, and each is more sensitive to change than to constant stimulation.
And, as was the case with vision and hearing, each of these senses is distinguished by
the type of information it extracts and by the specialized regions of the brain devoted
to it. Finally, the senses often act in concert, as when we see a lightning strike and hear
the ensuing clap of thunder or when the sensation we call “taste” really encompasses
a combination of flavor, odor, sight, and texture of food. Other common sensory com-
binations occur in sizzling steaks, fizzing colas, and bowls of Rice Krispies®.
Position and Movement To act purposefully and gracefully, we need constant infor-
mation about the position of our limbs and other body parts in relation to each other
and to objects in the environment. Without this information, even our simplest actions
Flute
Clarinet
Human voice
Explosion
Middle C on the piano
FIGURE 3.10
Waveforms of Familiar Sounds
Each sound is a distinctive combination
of several pure tones.
Source: Miller, D. C. (1916/1922). The Science
of musical sounds. New York: W. H. Freeman.
Reprinted by permission of Case Western Reserve
University.
TABLE 3.4 Fundamental Features of the Human Senses
Sense Stimulus Sense Organ Receptor Sensation
Vision Light waves Eye Rods and cones of
retina
Colors, brightness,
patterns, motion,
textures
Hearing Sound waves Ear Hair cells of the
basilar membrane
Pitch, loudness,
timbre
Skin senses External contact Skin Nerve endings in
skin
Touch, warmth,
cold
Smell Volatile
substances
Nose Hair cells of
olfactory epithelium
Odors
Taste Soluble
substances
Tongue Taste buds of
tongue
Flavors
Pain Many intense or
extreme stimuli:
temperature,
chemicals,
mechanical
stimuli, etc.
Net of pain
fibers all over
the body
Specialized
pain receptors,
overactive or
abnormal neurons
Acute pain,
chronic pain
Kinesthetic
and vestibular
senses
Body position,
movement, and
balance
Semicircular
canals, skeletal
muscles,
joints, tendons
Hair cells in
semicircular
canals; neurons
connected to
skeletal muscles,
joints, and tendons
Position of body
parts in space

How Are the Senses Alike? How Are They Different? 105
would be hopelessly uncoordinated. (You have probably had just this experience when
you tried to walk on a leg that had “gone to sleep.”) The physical mechanisms that
keep track of body position, movement, and balance actually consist of two different
systems, the vestibular sense and the kinesthetic sense.
The vestibular sense is the body position sense that orients us with respect to gravity.
It tells us the posture of our bodies—whether straight, leaning, reclining, or upside
down. The vestibular sense also tells us when we are moving or how our motion is
changing. The receptors for this information are tiny hairs (much like those we found
in the basilar membrane) in the semicircular canals of the inner ear (refer to Figure 3.8).
These hairs respond to our movements by detecting corresponding movements in the
fluid of the semicircular canals. Disorders of this sense can cause extreme dizziness and
disorientation.
The kinesthetic sense, the other sense of body position and movement, keeps track
of body parts relative to each other. Your kinesthetic sense makes you aware of cross-
ing your legs, for example, and tells you which hand is closer to your cell phone when
it rings. Kinesthesis provides constant sensory feedback about what the muscles in
your body are doing during motor activities, such as whether to continue reaching for
your cup of coffee or to stop before you knock it over (Turvey, 1996).
Receptors for kinesthesis reside in the joints, muscles, and tendons. These recep-
tors, as well as those for the vestibular sense, connect to processing regions in the
brain’s parietal lobes—which help us make a sensory “map” of the spatial relation-
ship among objects and events. This processing usually happens automatically and
effortlessly, outside of conscious awareness, except when we are deliberately learning
the movements for a new physical skill, such as swinging a golf club or playing a
musical instrument.
Smell Smell serves a protective function by sensing the odor of possibly dangerous
food or, for some animals, the scent of a predator. We humans seem to use the sense
of smell primarily in conjunction with taste to locate and identify calorie-dense foods,
avoid tainted foods, and, it seems, to identify potential mates—a fact capitalized on
by the perfume and cologne industry (Benson, 2002; Martins et al., 2005; Miller &
Maner, 2010).
Many animals take the sense of smell a step farther by exploiting it for communica-
tion. For example, insects such as ants and termites and vertebrates such as dogs and
cats communicate with each other by secreting and detecting odorous signals called
pheromones—especially to signal not only sexual receptivity but also danger, territorial
boundaries, food sources, and family members. It appears that the human use of the
sense of smell is much more limited.
The Biology of Olfaction Biologically, the sense of smell, or olfaction, begins with chemi-
cal events in the nose. There, odors (in the form of airborne chemical molecules) inter-
act with receptor proteins associated with specialized nerve cells (Axel, 1995; Turin,
2006). These cells, incidentally, are the body’s only nerve cells that come in direct con-
tact with the outside environment.
Odor molecules can be complex and varied. For example, freshly brewed coffee
owes its aroma to as many as 600 volatile compounds (Wilson & Stevenson, 2006).
More broadly, scientists have cataloged at least 1,500 different odor-producing mol-
ecules (Zimmer, 2010). Exactly how the nose makes sense of this cacophony of odors
is not completely understood, but we do know that nasal receptors sense the shape of
odor molecules (Foley & Matlin, 2010).
We also know that the nose’s receptor cells transduce information about the stimu-
lus and convey it to the brain’s olfactory bulbs, located on the underside of the brain
just below the frontal lobes (see Figure 3.11). There, our sensations of smell are ini-
tially processed and then passed on to many other parts of the brain (Mori et al.,
1999). Unlike all the other senses, smell signals are not relayed through the thalamus,
suggesting that smell has very ancient evolutionary roots.
vestibular sense The sense of body orientation
with respect to gravity. The vestibular sense is closely
associated with the inner ear and, in fact, is carried to
the brain on a branch of the auditory nerve.
kinesthetic sense The sense of body position
and movement of body parts relative to each other (also
called kinesthesis)
pheromones Chemical signals released by organ-
isms to communicate with other members of their spe-
cies. Pheromones are often used by animals as sexual
attractants. It is unclear whether or not humans employ
pheromones.
olfaction The sense of smell.
Gymnasts and dancers rely on their
vestibular and kinesthetic senses to
give them information about the position
and movement of their bodies.

106 C H A P T E R 3 Sensation and Perception
The Psychology of Smell Olfaction has an intimate connection with both emotion and
memory. This may explain why the olfactory bulbs lie very close to, and communicate
directly with, structures in the limbic system and temporal lobes that are associated
with emotion and memory. Therefore, it is not surprising that both psychologists and
writers have noticed that certain smells can evoke emotion-laden memories, sometimes
of otherwise-forgotten events (Dingfelder, 2004a). If you think about it for a moment,
you can probably recall a vivid memory “image” of the aroma associated with a favor-
ite food—perhaps fresh bread or a spicy dish—from your childhood.
Taste Like smell, taste is a sense based on chemistry. But the similarity doesn’t end
there: The senses of taste and smell have a close and cooperative working relationship—
so many of the subtle distinctions you may think of as flavors really come from odors.
(Much of the “taste” of an onion is odor, not flavor. And when you have a cold, you’ll
notice that food seems tasteless because your nasal passages are blocked.)
Most people know that our sense of taste, or gustation, involves four primary quali-
ties or dimensions: sweet, sour, bitter, and salty. Less well known, however, is a fifth taste
called umami (Chaudhari et al., 2000). Umami is the savory flavor found in protein-rich
foods, such as meat, seafood, and cheese. It is also associated with monosodium gluta-
mate (MSG), often used in Asian cuisine.
The taste receptor cells, located in the taste buds on the top and side of the tongue,
sample flavors from food and drink as they pass by on the way to the stomach. These
taste receptors cluster in small mucous-membrane projections called papillae, shown
in Figure 3.12. Each is especially sensitive to molecules of a particular shape.
Moving beyond the receptors on the tongue, a specialized nerve “hotline” carries
nothing but taste messages to specialized regions of the cortex. There, tastes are realized
in the parietal lobe’s somatosensory area. Conveniently, this region lies next to the patch
of cortex that receives touch stimulation from the face (Gadsby, 2000).
Developmental Changes in Taste Infants have heightened taste sensitivity, which is why
babies universally cringe at the bitter taste of lemon. This supersensitivity, however,
decreases with age. As a result, many elderly people complain that food has lost its
gustation The sense of taste, from the same word
root as “gusto;” also called the gustatory sense.
Frontal lobe of
cerebrum
Olfactory tract
Olfactory bulb
Olfactory nerves
Olfactory
epithelium
Olfactory bulb
Olfactory (l) nerves
Olfactory receptor cell
Olfactory hair (cilium)
Mucus layer
Substance being smelled
Dendrite
Connective tissue
Axon
A. Section through head, showing
the nasal cavity and the location of
olfactory receptors
B. Enlarged aspect of olfactory receptors
FIGURE 3.11
Receptors for Smell
Source: Zimbardo, P. G., & Gerrig, R. J. (1999). Psychology and life, 15th ed. Boston, MA: Allyn and Bacon. © 1999 by Pearson Education. Reprinted by permission of the publisher.

How Are the Senses Alike? How Are They Different? 107
taste—which really means that they have lost much of their sensory ability to detect
differences in the taste and smell of food. Compounding this effect, taste receptors can
be easily damaged by alcohol, smoke, acids, or hot foods. Fortunately, we frequently
replace our gustatory receptors—as we do our smell receptors. Because of this constant
renewal, the taste system boasts the most resistance to permanent damage of all our
senses, and a total loss of taste is extremely rare (Bartoshuk, 1990).
Supertasters Individuals of any age vary in their sensitivity to taste sensations, a function
of the density of papillae on the tongue (Bartoshuk, 2000, 2009; Bartoshuk et al., 1994).
Those with the most taste buds are supertasters who live in a “neon” taste world relative
to the rest of us—which accounts for their distaste for certain foods, such as broccoli or
“diet” drinks, in which they detect a disturbingly bitter flavor (Duenwald, 2005). Is there
any advantage to being a supertaster? Taste expert Linda Bartoshuk (1993) speculates
that, because most poisons are bitter, supertasters have a survival advantage.
Such differences also speak to the problem with which we began the chapter—in
particular, the question of whether different people sense the world in the same way.
Bartoshuk’s research suggests that, to the extent that the sense receptors exhibit some
variation from one person to another, so does our sensory experience of the world. This
variability is not so bizarre as to make one person’s sensation of sweet the same as another
person’s sensation of sour. Rather, the variations observed involve simply the intensity of
taste sensations, such as the bitter detected by supertasters. One big unknown, according
to Bartoshuk, is whether people differ in their sensitivities to different taste sensations:
for example, whether a person could be a supertaster for bitter while having only normal
sensations for sweet or salt (personal communication, January 4, 2011).
On the other hand, taste researchers have detected differences in taste preferences
between supertasters and those with normal taste sensations. In particular, supertasters
more often report disliking foods that they find too sweet or too fatty. Although the sig-
nificance of this remains to be determined, researchers have observed that supertasters,
on the average, weigh less than their nonsupertasting counterparts (Bartoshuk, 2000).
The Skin Senses Consider the skin’s remarkable versatility: It protects us against
surface injury, holds in body fluids, and helps regulate body temperature. The skin
also contains nerve endings that, when stimulated, produce sensations of touch, pain,
A. Top view of tongue B. Enlarged side view of papillae C. Enlarged view of taste bud
Papillae
Taste bud
Gustatory cell
FIGURE 3.12
Receptors for Taste
(A) Taste buds are clustered in papillae on the upper side of the tongue; (B) an enlarged view with individual papillae and taste buds
visible; (C) one of the taste buds enlarged.

108 C H A P T E R 3 Sensation and Perception
warmth, and cold. Like several other senses, these skin senses are connected to the so-
matosensory cortex located in the brain’s parietal lobes.
The skin’s sensitivity to stimulation varies tremendously over the body, depending
in part on the number of receptors in each area. For example, we are ten times more
accurate in sensing stimulation on our fingertips than stimulation on our backs. In
general, our sensitivity is greatest where we need it most—on our face, tongue, and
hands. Precise sensory feedback from these parts of the body permits effective eating,
speaking, and grasping.
One important aspect of skin sensitivity—touch—plays a central role in human
relationships. Through touch, we communicate our desire to give or receive comfort,
support, and love (Fisher, 1992; Harlow, 1965). Touch also serves as a primary stimu-
lus for sexual arousal in humans. And it is essential for healthy mental and physical
development; the lack of touch stimulation can stunt mental and motor development
(Anand & Scalzo, 2000).
Synesthesia: Sensations across the Senses
A small minority of otherwise “normal” people have a condition called synesthesia, which
allows them to sense their worlds across sensory domains. Some actually taste shapes—
so that pears may taste “round” and grapefruit “pointy” (Cytowic, 1993). Other synes-
thetes associate days of the week with colors—so that Wednesday may be “green” and
Thursday may be “red.” Their defining characteristic involves sensory experience that
links one sense with another.
Through clever experiments, V. S. Ramachandran and his colleagues have shown
that the cross-sensory sensations reported in synesthesia are real, not just metaphors
(Ramachandran & Hubbard, 2001). You can take one of their tests in the accompa-
nying Do It Yourself! box. Research also shows that this ability runs in families, so it
probably has a genetic component.
What causes synesthesia? Apparently it can involve communication between differ-
ent brain areas that process different sensations—often regions that lie close to each
other in the cortex. Brain imaging studies implicate a cortical area called the TPO,
lying at the junction of the temporal, parietal, and occipital lobes (Ramachandran &
Hubbard, 2003). This region simultaneously processes information coming from many
pathways. We all have some neural connections among these areas, theorizes Ramach-
andran, but synesthetes seem to have more than most.
The condition occurs slightly more often in highly creative people, Ramachandran
notes. And it may account for the “auras” purportedly seen around people by some mys-
tics (Holden, 2004). But perhaps we all have some cross-sensory abilities in us, which
may be why we resonate with Shakespeare’s famous metaphor in Romeo and Juliet,
“It is the east, and Juliet is the sun.” We know that he was not speaking literally, of
course. Rather we understand that, for Romeo—and so for us—Juliet is linked, across
our senses, with light, warmth, and sensory pleasure (Ramachandran & Hirstein, 1999).
skin senses Sensory systems for processing
touch, warmth, cold, texture, and pain.
synesthesia The mixing of sensations across
sensory modalities, as in tasting shapes or seeing
colors associated with numbers.
A SYNESTHESIA TEST
Most people will not have any trouble see-
ing the 5 while staring at the cross (left),
although the 5 becomes indistinct when
surrounded by other numbers (right). If
you are a synesthete who associates colors
with numbers, however, you may be able to
identify the 5 in the figure on the right be-
cause it appears as a blotch of the color as-
sociated with that number. (Adapted from
Ramachandran & Hubbard, 2003.)
3
+ 353+ 5
3

How Are the Senses Alike? How Are They Different? 109
PSYCHOLOGY MATTERS
The Sense and Experience of Pain
If you have severe pain, nothing else matters. A wound or a toothache can dominate
all other sensations. And if you are among the one-third of Americans who suffer from
persistent or recurring pain, the experience can be debilitating and can sometimes even
lead to suicide. Yet, pain is also part of your body’s adaptive mechanism that makes
you respond to conditions that threaten damage to your body.
Unlike other sensations, pain can arise from intense stimulation of various kinds, such
as a very loud sound, heavy pressure, a pinprick, or an extremely bright light. But pain is
not merely the result of stimulation. It is also affected by our moods and expectations, as
you know if you were ever anxious about going to the dentist (Koyama et al., 2005).
Pain Receptors
In the skin, several types of specialized nerve cells, called nociceptors, sense painful
stimuli and send their unpleasant messages to the central nervous system. Some noci-
ceptors are most sensitive to heat, while others respond mainly to pressure, chemical
trauma, or other tissue injury (Foley & Matlin, 2010). There are even specialized noci-
ceptors for the sensation of itching—itself a type of pain (Gieler & Walter, 2008).
A Pain in the Brain
Even though they may seem to emanate from far-flung parts of the body, we actually
feel painful sensations in the brain. There are two distinct regions that have primary
roles in processing incoming pain messages (Foley & Matlin, 2010; Porreca & Price,
2009). One, involving a pathway terminating in the parietal lobe, registers the loca-
tion, intensity, and the sharpness or dullness of pain. The other, a group of structures
deep in the frontal cortex and in the limbic system, registers just how unpleasant the
painful sensation is. People with damage to this second region may notice a painful
stimulus but report that it does not feel unpleasant.
Phantom Limbs
One intriguing puzzle about pain concerns the mysterious sensations often experienced
by people who have lost an arm or leg—a condition known as a phantom limb. In
such cases, the amputee feels sensations—sometimes quite painful ones—that seem to
come from the missing body part (Ramachandran & Blakeslee, 1998). Neurological
studies show that the phantom limb sensations do not originate in damaged nerves in
the sensory pathways. Nor are they purely imaginary. Rather, they arise in the brain
itself—perhaps the result of the brain generating sensation when none comes from the
missing limb (Dingfelder, 2007). The odd phenomenon of phantom limbs teaches us
that understanding pain requires understanding not only painful sensations but also
mechanisms in the brain that both process and inhibit pain.
The Gate-Control Theory
No one has yet developed a theory that explains everything about pain, but Melzack
and Wall’s (1965, 1983) gate-control theory explains a lot. In particular, it explains why
pain can sometimes be blocked or facilitated “top-down” by our mental state. The
“gate” itself involves special interneurons that can open or close the pain pathway run-
ning up the spinal cord toward the brain. Closing the gate interferes with the transmis-
sion of pain messages in the spinal pathway.
What can close the gate? Messages from nonpain nerve fibers, such as those involved
in touch, can inhibit pain transmission. This explains why you vigorously shake your
hand when you hit your finger with a hammer. Just as important, messages from the brain
can also close the gate. This is how opiate drugs, such as morphine, work—by initiating
a cascade of inhibitory messages that travel downward to block incoming pain messages.
gate-control theory An explanation for pain
control that proposes we have a neural “gate” that
can, under some circumstances, block incoming pain
signals.

110 C H A P T E R 3 Sensation and Perception
The gate on the pain pathway can also be opened and closed, such as hypnosis
or the distraction of important events. (See Fields, 2009.) We have long known that
people’s interpretations of events affect whether or not stimuli are perceived as painful
(Turk, 1994). For example, soldiers and athletes may suffer severe injuries that cause
little pain until the excitement of the battle or contest is over. And as we will see in a
moment, this mind–body effect on pain is evident in the action of placebos or other
sham treatments.
Dealing with Pain
Wouldn’t it be nice to banish the experience of pain altogether? In reality, such a con-
dition can be deadly. People with congenital insensitivity to pain do not feel what is
hurting them, and their bodies often become scarred and their limbs deformed from
injuries they could have avoided if their brains were able to warn them of danger.
Because of their failure to notice and respond to tissue-damaging stimuli, these people
tend to die young (Manfredi et al., 1981).
In general, pain serves as an essential defense signal: It warns us of potential harm,
and it helps us to survive in hostile environments and to get treatment for sickness and in-
jury. Sometimes, however, chronic pain seems to be a disease in itself, with neurons in the
pain pathways becoming hypersensitive, amplifying normal sensory stimulation into pain
messages (Watkins & Maier, 2003). Research also suggests that chronic pain may, at least
sometimes, arise from genes that get “turned on” in nerve-damaged tissue (Marx, 2004).
Analgesics
What can you do if you are in pain? Analgesic drugs, ranging from over-the-counter
remedies such as aspirin and ibuprofen to prescription narcotics such as morphine, are
widely used and effective. These act in a variety of ways. Morphine suppresses pain
messages in the spinal cord and the brain; aspirin interferes with a chemical signal pro-
duced by damaged tissue (Basbaum & Julius, 2006; Carlson, 2007). Those using pain-
killing drugs should be aware of unwanted side effects, such as digestive tract or liver
damage and even addiction. But studies have shown that if you must use narcotics to
control severe pain, the possibility of your becoming addicted is far less than it would
be if you were using narcotics recreationally (Melzack, 1990).
Psychological Techniques for Pain Control
Many people can also learn to control pain by psychological techniques, such as hyp-
nosis, relaxation, and thought-distraction procedures (Brown, 1998). For instance, a
child receiving a shot at the doctor’s office might be asked to take a series of deep
breaths and look away. You also may be among those for whom pain can also be
modified by placebos, mock drugs made to appear as real drugs. For example, a pla-
cebo may be an injection of mild saline solution (salt water) or a pill made of sugar.
Such fake drugs are routinely given to a control group in tests of new pain drugs. Their
effectiveness, of course, involves the people’s belief that they are getting real medicine
(Niemi, 2009; Wager, 2005; Wager et al., 2004). It is important to note, however, that
the brain’s response to a placebo is much the same as that of pain-relieving drugs: clos-
ing the spinal gate. Because this placebo effect is common, any drug deemed effective
must prove itself stronger than a placebo.
How do placebos produce their effects? Apparently, the expectation of pain relief
is enough to cause the brain to release painkilling endorphins. We believe this is so
because brain scans show that essentially the same pain-suppression areas “light up”
when patients take placebos or analgesic drugs (Petrovic et al., 2002). Further, we find
that individuals who respond to placebos report that their pain increases when they
take the endorphin-blocking drug naltrexone (Fields, 1978; Fields & Levine, 1984).
Surprisingly, the placebo effect doesn’t necessarily require a placebo! In a con-
trolled experiment, Dr. Fabrizio Benedetti and his colleagues (2005) showed that the
physician’s bedside manner, even without a painkilling drug, can suppress pain. For
psychologists, this is an important discovery, demonstrating that the psychosocial con-
text itself can have a therapeutic effect (Guterman, 2005).
placebo Substance that appears to be a drug but
is not. Placebos are often referred to as “sugar pills”
because they might contain only sugar rather than a
real drug.
placebo effect A response to a placebo (a fake
drug) caused by the belief that it is a real drug.

How Are the Senses Alike? How Are They Different? 111
Controlling Psychological Pain with Analgesics
In another surprising development, psychologist C. Nathan DeWall and his colleagues
(2010) have found that acetaminophen (the pain reliever in Tylenol) can lessen the psy-
chological pain of social rejection. Volunteers who took acetaminophen, as compared
with those taking placebos, reported far fewer feelings of social rejection in everyday
life. And in a follow-up experimental study involving a computer game rigged to make
players feel social rejection, fMRI scans showed that acetaminophen reduced activity
in brain areas associated with social rejection and also with physical pain. What makes
this research interesting is the suggestion that both physical and psychological hurts
involve some of the same pain mechanisms in the brain.
Pain Tolerance
The threshold of pain varies enormously from person to person. Some people always
demand Novocain from their dentist, while others may prefer dental work without the
added hassle of an injection. And in the laboratory, one study found that electric shocks
had to be eight times more powerful to produce painful sensations in their least-sensitive
subjects as compared with their most-sensitive subjects (Rollman & Harris, 1987). An-
other experiment found that brain scans of people who are highly sensitive to pain show
greater activation of the thalamus and the anterior cingulate cortex than in scans of
those with greater pain tolerance (Coghill et al., 2003). At least part of this variation has
a genetic basis (Couzin, 2006).
We should be clear on this point: There is no evidence of genetic differences in
sensitivity to pain among different ethnic or racial groups, although many reports suggest
that culture does affect how people interpret pain and respond to painful stimulation. For
example, Western women often report that childbirth is an excruciatingly painful experi-
ence, while women in some cultures routinely give birth with little indication of distress.
Severely wounded soldiers, too, typically need less pain medication than do civilians with
comparable injuries—perhaps because of the “culture of bravery” instilled in soldiers or
because a soldier knows that a wound represents a ticket out of the combat zone.
Readers should be cautioned, however, that much of the literature on cultural
differences in response to pain relies far more on anecdotes than on controlled studies.
Further, the scientific work that does exist in this area has frequently come to conflict-
ing conclusions (Foster, 2006). Perhaps one of the most important influences to emerge
from this work involves poverty and access to health care: Poor people are much less
likely to seek medical attention until pain becomes severe.
Check Your Understanding
1. RECALL: Name the two types of photoreceptors and indicate what
sort of stimulation they detect.
2. RECALL: The wavelength of light causes sensations of ,
while the intensity of light causes sensations of .
a. motion/shape
b. color/brightness
c. primary colors/secondary colors
d. depth/color
3. RECALL: The frequency theory best explains how we hear
sounds, while the place theory best explains how we
hear sounds.
4. SYNTHESIS: What do all of the following senses have in common:
vision, hearing, taste, smell, hearing, pain, equilibrium, and body
position?
5. RECALL: Studies of painful phantom limbs show that the phantom
pain originates in
a. the brain.
b. nerve cells damaged from the amputation.
c. the imagination.
d. ascending pathways in the spinal cord.
6. UNDERSTANDING THE CORE CONCEPT: Explain why
different senses give us different sensations.
Answers 1. The rods are better than the cones for detecting objects in dim light. The cones give us high-resolution color vision in relatively bright
light. 2. b (color/brightness) 3. low-pitched/high-pitched 4. Each of these senses transduces physical stimulation into neural activity, and each
responds more to change than to constant stimulation. 5. a (the brain) 6. The different sensations occur because the sensory information is
processed by different parts of the brain.
Study and Review at MyPsychLab

112 C H A P T E R 3 Sensation and Perception
3.3 KEY QUESTION
What Is the Relationship between Sensation
and Perception?
We have described how sensory signals are transduced and transmitted to specific
regions of your brain for further processing as visual images, pain, odors, and other
sensations. Then what? You enlist your brain’s perceptual machinery to attach meaning
to the incoming sensory information. Does a bitter taste mean poison? Does a red
flag mean danger? Does a smile signify a friendly overture? The Core Concept of this
section emphasizes this perceptual elaboration of sensory information:
Core Concept 3.3
Perception brings meaning to sensation, so perception produces an
interpretation of the world, not a perfect representation of it.
In brief, we might say that the task of perception is to organize sensation into stable,
meaningful percepts. A percept, then, is not just a sensation but the associated mean-
ing as well. As we describe this complex perceptual process, we will first consider how
our perceptual apparatus usually manages to give us a reasonably accurate and useful
image of the world. Then we will look at some illusions and other instances in which
perception apparently fails spectacularly. Finally, we will examine two theories that
attempt to capture the most fundamental principles at work behind these perceptual
successes and failures.
Perceptual Processing: Finding Meaning in Sensation
How does the sensory image of a person (such as the individual pictured in Figure
3.13) become the percept of someone you recognize? That is, how does mere sensa-
tion become an elaborate and meaningful perception? Let’s begin with two visual
pathways that help us identify objects and locate them in space: the what pathway
and the where pathway.
The What and Where Pathways in the Brain The primary visual cortex, at the
back of the brain, splits visual information into two interconnected streams (Fariva,
2009; Goodale & Milner, 1992). One stream, which flows mainly to the temporal
lobe, extracts information about an object’s color and shape. This what pathway al-
lows us to determine what objects are. The other stream, the where pathway, projects to
the parietal lobe, which determines an object’s location. Evidence suggests that other
senses, such as touch and hearing, also have what and where streams that interact with
those in the visual system (Rauschecker & Tian, 2000).
Curiously, we are conscious of information in the what pathway but not necessarily
in the where pathway. This fact explains a curious phenomenon known as blindsight, a
condition that occurs in some people with damage to the what pathway—damage that
makes them visually unaware of objects around them. Yet if the where pathway is in-
tact, blindsight patients may be able to step over objects in their path or reach out and
touch objects that they claim not to see (Ramachandran & Rogers-Ramachandran,
2008). In this way, persons with blindsight are much like a sophisticated robot that can
sense and react to objects around it even though it lacks the ability to represent them
in consciousness.
Feature Detectors The deeper information travels into the brain along the what
and where pathways, the more specialized processing becomes. Ultimately, specialized
groups of cells in the visual pathways extract very specific stimulus features, such as
an object’s length, slant, color, boundary, location, and movement (Kandel & Squire,
2000). Perceptual psychologists call these cells feature detectors.
percept The meaningful product of perception—
often an image that has been associated with con-
cepts, memories of events, emotions, and motives.
what pathway A neural pathway, projecting from
the primary visual cortex to the temporal lobe, which
involves identifying objects.
where pathway A neural pathway that projects
visual information to the parietal lobe; responsible for
locating objects in space.
blindsight The ability to locate objects despite
damage to the visual system making it impossible for
a person consciously to see and identify objects. Blind-
sight is thought to involve unconscious visual process-
ing in the where pathway.
feature detectors Cells in the cortex that spe-
cialize in extracting certain features of a stimulus.
FIGURE 3.13
Who Is This?
Perceptual processes help us recognize
people and objects by matching the
stimulus to images in memory.

What Is the Relationship between Sensation and Perception? 113
We know about feature detectors from animal experiments and also from
cases like Jonathan’s, in which brain injury or disease selectively robs an
individual of the ability to detect certain features, such as colors or shapes.
There is even a part of the temporal lobe—near the occipital cortex—with
feature detectors that are especially sensitive to features of the human face
(Carpenter, 1999).
Despite our extensive knowledge of feature detectors, we still don’t know
exactly how the brain manages to combine (or “bind”) the multiple features
it detects into a single percept of, say, a face. Psychologists call this puzzle the
binding problem, and it may be the deepest mystery of perceptual psychology
(Kandel & Squire, 2000).
We do have one tantalizing piece of this perceptual puzzle: Neuroscien-
tists have discovered that the brain synchronizes the firing patterns in differ-
ent groups of neurons that have each detected different features of the same
object—much as an orchestra conductor determines the tempo at which all
members of the ensemble will play a musical piece (Buzsáki, 2006). But just
how this synchronization is involved in “binding” these features together
remains a mystery.
Top-Down and Bottom-Up Processing Forming a percept also seems to
involve imposing a pattern on sensation. This involves two complementary
processes that psychologists call top-down processing and bottom-up pro-
cessing. In top-down processing, our goals, past experience, knowledge, expectations,
memory, motivations, or cultural background guide our perceptions of objects—or
events (see Nelson, 1993). Trying to find your car keys in a cluttered room requires
top-down processing. So does searching for Waldo in the popular children’s series
Where’s Waldo? And if you skip lunch to go grocery shopping, top-down hunger sig-
nals will probably make you notice all the snack foods in the store.
In bottom-up processing, the characteristics of the stimulus (rather than a concept
in our minds) exert a strong influence on our perceptions. Bottom-up processing relies
heavily on the brain’s feature detectors to sense these stimulus characteristics: Is it
moving? What color is it? Is it loud, sweet, painful, pleasant smelling, wet, hot…? You
are doing bottom-up processing when you notice a moving fish in an aquarium, a hot
pepper in a stir-fry, or a loud noise in the middle of the night.
Thus, bottom-up processing involves sending sensory data into the system through
receptors and sending it “upward” to the cortex, where a basic analysis, involving the
feature detectors, is first performed to determine the characteristics of the stimulus.
Psychologists also refer to this as stimulus-driven processing because the resulting per-
cept is determined, or “driven,” by stimulus features. By contrast, top-down processing
flows in the opposite direction, with the percept being driven by some concept in the
cortex—at the “top” of the brain. Because this sort of thinking relies heavily on con-
cepts in the perceiver’s own mind, it is also known as conceptually driven processing.
Perceptual Constancies We can illustrate another aspect of perception with yet
another example of top-down processing. Suppose that you are looking at a door, such
as the one pictured in Figure 3.14A. You “know” that the door is rectangular, even
though your sensory image of it is distorted when you are not looking at it straight-on.
Your brain automatically corrects the sensory distortion so that you perceive the door
as being rectangular, as in Figure 3.14B.
This ability to see an object as being the same shape from different angles or
distances is just one example of a perceptual constancy. In fact, there are many kinds of
perceptual constancies. These include color constancy, which allows us to see a flower
as being the same color in the reddish light of sunset as in the white glare of midday.
Size constancy allows us to perceive a person as the same size at different distances
and also serves as a strong cue for depth perception. And it was shape constancy that
allowed us to see the door as remaining rectangular from different angles. Together,
these constancies help us identify and track objects in a changing world.
binding problem Refers to the process used by
the brain to combine (or “bind”) the results of many
sensory operations into a single percept. This occurs,
for example, when sensations of color, shape, bound-
ary, and texture are combined to produce the percept
of a person’s face. No one knows exactly how the brain
does this. Thus, the binding problem is one of the major
unsolved mysteries in psychology.
top-down processing Perceptual analysis
that emphasizes the perceiver’s expectations, concept
memories, and other cognitive factors, rather than be-
ing driven by the characteristics of the stimulus. “Top”
refers to a mental set in the brain—which stands at
the “top” of the perceptual processing system.
bottom-up processing Perceptual analysis
that emphasizes characteristics of the stimulus, rather
than our concepts and expectations. “Bottom” refers
to the stimulus, which occurs at step one of perceptual
processing.
perceptual constancy The ability to recognize
the same object as remaining “constant” under dif-
ferent conditions, such as changes in illumination,
distance, or location.
Many viewers report that the flowers in Claude
Monet’s floral paintings, such as Coquelicots,
produce a shimmering or moving sensation. Neu-
roscientists believe this occurs because the colors
of the flowers have the same level of brightness as
the colors in the surrounding field—and so are dif-
ficult for the colorblind “where” pathway to locate
precisely in space (Dingfelder, 2010).

114 C H A P T E R 3 Sensation and Perception
Inattentional Blindness and Change Blindness Some-
times we don’t notice things that occur right in front of our
noses—particularly if they are unexpected and we haven’t
focused our attention on them. While driving, you may not
notice a car unexpectedly shifting lanes. Psychologists call
this inattentional blindness (Beck et al., 2004; Greer, 2004a).
Magicians rely on it for many of their tricks (Sanders,
2009). They also rely on change blindness, a related phe-
nomenon in which we fail to notice that something is dif-
ferent now than it was before, as when a friend changes
hair color or shaves a mustache (Martinez-Conde &
Macknik, 2008).
We do notice changes that we anticipate, such as a red
light turning to green. But laboratory studies show that
many people don’t notice when, in a series of photographs
of the same scene, a red light is replaced by a stop sign.
One way this may cause trouble in the world outside the
laboratory is that people underestimate the extent to which
they can be affected by change blindness. This probably
occurs because our perceptual systems and our attention
have limits on the amount of information they can process,
so our expectations coming from the “top down” cause us
to overlook the unexpected.
Perceptual Ambiguity and Distortion
A primary goal of perception is to get an accurate “fix” on the world—to recognize
friends, foes, opportunities, and dangers. Survival sometimes depends on accurately
perceiving the environment, but the environment is not always easy to “read.” We
can illustrate this difficulty with the photo of black and white splotches in Figure
3.15. What is it? When you eventually extract the stimulus figure from the back-
ground, you will see it as a Dalmatian dog walking toward the upper left with its
head down. The dog is hard to find because it blends so easily with the background.
The same problem occurs when you try to single out a voice against the background
of a noisy party.
But it is not just the inability to find an image that causes
perceptual problems. Sometimes our perceptions can be wildly
inaccurate because we misinterpret an image—as happens with
sensory and perceptual illusions.
What Illusions Tell Us about Sensation and Perception When
your mind deceives you by interpreting a stimulus pattern incor-
rectly, you are experiencing an illusion. Such illusions can help
us understand some fundamental properties of sensation and
perception—particularly the discrepancy between our percepts and
external reality (Cohen & Girgus, 1973).
Let’s first examine a remarkable bottom-up illusion that
works at the level of sensation: the black-and-white Hermann
grid (see Figure 3.16). As you stare at the center of the grid, note
how dark, fuzzy spots appear at the intersections of the white
bars. But when you focus on an intersection, the spot vanishes.
Why? The answer lies in the way receptor cells in your visual
pathways interact with each other. The firing of certain cells that
are sensitive to light–dark boundaries inhibits the activity of
adjacent cells that would otherwise detect the white grid lines.
This inhibiting process makes you sense darker regions—the
inattentional blindness A failure to notice
changes occurring in one’s visual field, apparently
caused by narrowing the focus of one’s attention.
change blindness A perceptual failure to notice
that a visual scene has changed from the way it had
appeared previously. Unlike inattentional blindness,
change blindness requires comparing a current scene
to one from the past, stored in memory.
illusion You have experienced an illusion when you
have a demonstrably incorrect perception of a stimulus
pattern, especially one that also fools others who are
observing the same stimulus. (If no one else sees it the
way you do, you could be having a hallucination. We’ll
take that term up in a later chapter on mental disorder.)
FIGURE 3.15
An Ambiguous Picture
What is depicted here? The difficulty in seeing the figure lies in
its similarity to the background.
FIGURE 3.14
A Door by Any Other Shape Is Still a Door
(A) A door seen from an angle presents the eye with a distorted rect-
angle image. (B) The brain perceives the door as rectangular.

(A) (B)

What Is the Relationship between Sensation and Perception? 115
grayish areas—at the white intersections just outside your focus. Even though you
know (top-down) that the squares in the Hermann grid are black and the lines are
white, this knowledge cannot overcome the illusion, which operates at a more basic,
sensory level.
To study illusions at the level of perception, psychologists often employ ambiguous
figures—stimulus patterns that can be interpreted (top-down) in two or more distinct
ways, as in Figures 3.17A and 3.17B. There you see that both the vase/faces figure and
the Necker cube are designed to confound your interpretations, not just your sensa-
tions. Each suggests two conflicting meanings: Once you have seen both, your percep-
tion will cycle back and forth between them as you look at the figure. Studies suggest
that these alternating interpretations may involve the shifting of perceptual control
between the left and right hemispheres of the brain (Gibbs, 2001).
Another dramatic illusion, recently discovered, appears in Figure 3.18. Although
it is hard to believe, the squares marked A and B are the same shade of gray. Proof
appears in the right-hand image, where the vertical bars are also the same gray shade.
Why are we fooled by this illusion? Perceptual psychologists respond that the effect
derives from color and brightness constancy: our ability to see an object as essentially
unchanged under different lighting conditions, from the bright noon sun to near dark-
ness (Gilchrist, 2006). Under normal conditions, this prevents us from being misled
by shadows.
Figure 3.19 shows several other illusions that operate primarily at the level of
perceptual interpretation. All are compelling, and all are controversial—particu-
larly the Müller–Lyer illusion, which has intrigued psychologists for more than 100
years. Disregarding the arrowheads, which of the two horizontal lines in this fig-
ure appears longer? If you measure them, you will see that the horizontal lines are
exactly the same length. What is the explanation? Answers to that question have
ambiguous figures Images that can be inter-
preted in more than one way. There is no “right” way to
see an ambiguous figure.
FIGURE 3.16
The Hermann Grid
Why do faint gray dots appear at the intersections of
the grid? The illusion, which operates at the sensory
level, is explained in the text.
Source: Levine, M. W., & Shefner, J. (2000). Fundamentals
of sensation & perception. New York: Oxford University Press.
Reprinted by permission of Michael W. Levine.
FIGURE 3.18
The Checkerboard Illusion
Appearances are deceiving: Squares A
and B are actually the same shade of
gray, as you can see on the right by com-
paring the squares with the vertical bars.
The text explains why this occurs.
Source: Adelson, E. H. (2010). Checkershadow
illusion. Retrieved from http://persci.mit.edu/gallery/
checkershadow. © 1995, Edward H. Adelson.
Vase or faces?
A.
B.
The Necker cube:
above or below?
FIGURE 3.17
Perceptual Illusions
These ambiguous figures
are illusions of perceptual
interpretation.

Checker Shadow Illusion

116 C H A P T E R 3 Sensation and Perception
been offered in well over a thousand published studies, and psychologists still don’t
know for sure.
One popular theory, combining both top-down and bottom-up factors, has gath-
ered some support. It suggests that we unconsciously interpret the Müller–Lyer figures
as three-dimensional objects. So instead of arrowheads, we see the ends as angles that
project toward or away from us like the inside and outside corners of a building or a
room, as in Figure 3.20 The inside corner seems to recede in the distance, while the
outside corner appears to extend toward us. Therefore, we judge the outside corner to
be closer—and shorter. Why? When two objects make the same-size image on the retina
and we judge one to be farther away than the other, we assume that the more distant
one is larger.
Illusions in the Context of Culture But what if you had grown up in a culture
with no square-cornered buildings? Would you still see one line as longer than the
other in the Müller–Lyer? In other words, do you have to learn to see the illusion,
or is it “hard wired” into your brain? One way to answer such questions is through
cross-cultural research. With this in mind, Richard Gregory (1977) went to South
Africa to study a group of people known as the Zulus, who live in what he called
a “circular culture.” Aesthetically, people in that culture prefer curves to straight
lines and square corners: Their round huts have round doors and windows; they till
Is the hat taller than the
brim is wide?
Is the diagonal line
straight or broken?
Turning the tables: Could the table tops be the same size?
Top hat illusion Poggendorf illusion
Which central circle is bigger?
a b
Ebbinghaus illusion
Are the vertical lines parallel?Which horizontal line is longer?
a b
c d
Müller–Lyer illusion Zöllner illusion
FIGURE 3.19
Six Illusions to Tease Your Brain
Each of these illusions involves a bad “bet” made by your brain. What explanations can you give for the distortion of reality that each of these illu-
sions produces? Are they caused by nature or nurture? The table illusion was originally developed by Roger N. Shepard and presented in his 1990
book Mind Sights (Freeman).

What Is the Relationship between Sensation and Perception? 117
their fields along sweeping curved lines, using curved plows; the children’s toys lack
straight lines.
So what happened when Gregory showed them the Müller–Lyer? Most saw the
lines as nearly the same length. This suggests that the Müller–Lyer illusion is learned.
A number of other studies support Gregory’s conclusion that people who live in “car-
pentered” environments—where buildings are built with straight sides and 90-degree
angles—are more susceptible to the illusion than those who (like the Zulus) live in
“noncarpentered” worlds (Segall et al., 1999).
Applying the Lessons of Illusions Several prominent modern artists, fascinated
with the visual experiences created by ambiguity, have used perceptual illusion as a
central artistic feature of their work. Consider the two examples of art shown here.
Gestalt-Rugo by Victor Vasarely (see Figure 3.21) produces depth reversals like those
in the Necker cube, with corners that alternately project and recede. In Sky and Water
by M. C. Escher (see Figure 3.22), you can see birds and fishes only through the
process of figure–ground reversal, much like the vase/faces illusion we encountered
earlier (see Figure 3.17). The effect of these paintings on us underscores the function
of human perception to make sense of the world and to fix on the best interpretation
we can make.
To interpret such illusions, we draw on our personal experiences, learning, and
motivation. Knowing this, those who understand the principles of perception often can
control illusions to achieve desired effects far beyond the world of painting. Architects
and interior designers, for example, create illusions that make spaces seem larger or
smaller than they really are. They may, for example, make a small apartment appear
more spacious when it is painted in light colors and sparsely furnished. Similarly, set
and lighting designers in movies and theatrical productions purposely create visual
illusions on film and on stage. So, too, do many of us make everyday use of illusion in
our choices of cosmetics and clothing (Dackman, 1986). Light-colored clothing and
horizontal stripes can make our bodies seem larger, while dark-colored clothing and
vertical stripes can make our bodies seem slimmer. In such ways, we use illusions to
distort “reality” and make our lives more pleasant.
Theoretical Explanations for Perception
The fact that most people perceive most illusions and ambiguous figures in essen-
tially the same way suggests that fundamental perceptual principles are at work. But
what are these principles? To find some answers, we will examine two influential the-
ories that explain how we form our perceptions: Gestalt theory and learning-based
inference.
Although these two approaches may seem contradictory at first, they really empha-
size complementary influences on perception. The Gestalt theory emphasizes how we
organize incoming stimulation into meaningful perceptual patterns—because of the
FIGURE 3.20
The Müller-Lyer Illusion
One explanation for the Müller-Lyer il-
lusion says that your brain thinks it is
seeing the inside and outside corners of a
building in perspective.
BA
FIGURE 3.21
Victor Vasarely’s Gestalt-Rugo
FIGURE 3.22
M. C. Escher’s Sky and Water

118 C H A P T E R 3 Sensation and Perception
way our brains are innately ”wired.” On the other hand, learning-based inference em-
phasizes learned influences on perception, including the power of expectations, con-
text, and culture. In other words, Gestalt theory emphasizes nature, and learning-based
inference emphasizes nurture.
Perceptual Organization: The Gestalt Theory You may have noticed that a series of
blinking lights, perhaps on a theater marquee, can create the illusion of motion where
there really is no motion. Similarly, there appears to be a white triangle in the Do It
Yourself! box on this page—but there really is no white triangle. And, as we have seen,
the Necker cube seems to flip back and forth between two alternative perspectives—
but, of course, the flipping is all in your mind.
About 100 years ago, such perceptual tricks captured the interest of a group of
German psychologists, who argued that the brain is innately wired to perceive not just
stimuli but also patterns in stimulation (Sharps &Wertheimer, 2000). They called such a
pattern a Gestalt, the German word for “perceptual pattern” or “configuration.” Thus,
from the raw material of stimulation, the brain forms a perceptual whole that is more
than the mere sum of its sensory parts (Prinzmetal, 1995; Rock & Palmer, 1990). This
perspective became known as Gestalt psychology.
The Gestaltists liked to point out that we perceive a square as a single figure rather
than merely as four individual lines. Similarly, when you hear a familiar song, you do
not focus on the individual notes. Rather, your brain extracts the melody, which is
your perception of the overall pattern of notes. Such examples, the Gestalt psycholo-
gists argued, show that we always attempt to organize sensory information into mean-
ingful patterns, the most basic elements of which are already present in our brains
at birth. Because this approach has been so influential, we will examine some of the
Gestalt discoveries in more detail.
Figure and Ground One of the most basic of perceptual processes identified by Gestalt
psychology divides our perceptual experience into figure and ground. A figure is simply
a pattern or image that grabs our attention. As we noted, psychologists sometimes call
this a Gestalt. Everything else becomes ground, the backdrop against which we perceive
C O N N E C T I O N CHAPTER 1
The nature–nurture issue centers
on the relative importance of
heredity and environment (p. 44).
Gestalt psychology From a German word (pro-
nounced gush-TAWLT) that means “whole” or “form”
or “configuration.” (A Gestalt is also a percept.) The
Gestalt psychologists believed that much of perception
is shaped by innate factors built into the brain.
figure The part of a pattern that commands atten-
tion. The figure stands out against the ground.
ground The part of a pattern that does not
command attention; the background.
object that obscures the ground behind
it. (That’s why we often call the ground a
“background.”)
FIGURE OBSCURES GROUND
The tendency to perceive a figure as be-
ing in front of a ground is strong. It is so
strong, in fact, that you can even get this
effect when the perceived figure doesn’t
actually exist! You can demonstrate this
with an examination of the accompany-
ing figure. (See also Ramachandran &
Rogers-Ramachandran, 2010.) You prob-
ably perceive a fir-tree shape against a
ground of red circles on a white surface.
But, of course, there is no fir-tree figure
printed on the page; the figure consists
only of three solid red shapes and a
black-line base. You perceive the illusory
white triangle in front because the wedge-
shaped cuts in the red circles seem to
be the corners of a solid white triangle.
To see an illusory six-pointed star, look
at part B. Here, the nonexistent “top”
triangle appears to blot out parts of red
circles and a black-lined triangle, when
in fact none of these is depicted as com-
plete figures. Again, this demonstrates
that we prefer to see the figure as an
A B
Subjective Contours
(A) A subjective fir tree; (B) a subjective six-pointed star.
Listen to the Podcast
MyPsychLab
Gestalt
Principles at Work at

What Is the Relationship between Sensation and Perception? 119
the figure. A melody becomes a figure heard against a background of complex harmo-
nies, and a spicy chunk of pepperoni becomes the figure against the ground of cheese,
sauce, and bread that makes up a pizza. Visually, a figure could be a bright flashing
sign or a word on the background of a page. And in the ambiguous faces/vase seen in
Figure 3.17A, figure and ground reverse when the faces and vase alternately “pop out”
as figure.
Closure: Filling in the Blanks Our minds seem built to abhor a gap, as you saw in the
Do It Yourself! above. Note especially the illusory white triangle—superimposed on
red circles and black lines. Moreover, you will note that you have mentally divided
the white area into two regions, the triangle and the background. Where this division
occurs, you perceive subjective contours: boundaries that exist not in the stimulus but
only in the subjective experience of your mind.
Your perception of these illusory triangles demonstrates a second powerful orga-
nizing process identified by the Gestalt psychologists. Closure makes you see incomplete
figures as wholes by supplying the missing segments, filling in gaps, and making infer-
ences about potentially hidden objects. So when you see a face peeking around a cor-
ner, your mind automatically fills in the hidden parts of the face and body. In general,
humans have a natural tendency to perceive stimuli as complete and balanced even
when pieces are missing. (Does this ring a with you?) Closure is also respon-
sible for filling in your “blind spot,” as you saw on page 97.
In the foregoing demonstrations, we have seen how the perception of subjective
contours and closure derives from the brain’s ability to create percepts out of incom-
plete stimulation. Now let us turn to the perceptual laws that explain how we group
the stimulus elements that are actually present in Gestalts.
The Gestalt Laws of Perceptual Grouping It’s easy to see a school of fish as a single unit—
as a Gestalt. But why? And how do we mentally combine hundreds of notes together
and perceive them as a single melody? How do we combine the elements of color,
shadow, form, texture, and boundary into the percept of a friend’s face? And why have
thousands of people reported seeing “flying saucers” or the face of Jesus in the scorch
marks on a tortilla? That is, how do we pull together in our minds the separate stimu-
lus elements that seem to “belong” together? This is the binding problem again: one of
the most fundamental problems in psychology. As we will see, the Gestalt psycholo-
gists made great strides in this area, even though the processes by which perceptual
organization works are still debated today (Palmer, 2002).
In the heyday of Gestalt psychology, of course, there were no MRIs or PET scans.
Modern neuroscience didn’t exist. Hence, Gestalt psychologists like Max Wertheimer
(1923) had to focus on the problem of perceptual organization in a different way—with
closure The Gestalt principle that identifies the
tendency to fill in gaps in figures and to see incomplete
figures as complete.
FIGURE 3.23
Gestalt Laws of Perceptual Grouping
Because of similarity, in (A), you most
easily see the Xs grouped together, while
Os form a separate Gestalt. So columns
group together more easily than rows.
The rows, made up of dissimilar ele-
ments, do not form patterns so easily. In
(B), proximity makes dissimilar elements
easily group together when they are near
each other. In (C), even though the lines
cut each other into many discontinuous
segments, continuity makes it easier to
see just two lines—each of which appears
to be continuous as a single line cutting
through the figure.
A. Similarity B. Proximity
C. Continuity
X O X O X
X O X O X
X O X O X O X O X O X O X OX
X O X O X
X O X O X

120 C H A P T E R 3 Sensation and Perception
arrays of simple figures, such as you see in Figure 3.23. By varying a single factor and
observing how it affected the way people perceived the structure of the array, Wert-
heimer was able to formulate a set of laws of perceptual grouping, which he inferred were
built into the neural fabric of the brain.
According to Wertheimer’s law of similarity, we group things together that have a
similar look (or sound, or feel, and so on). So in Figure 3.23A, you see that the Xs and
Os form distinct columns, rather than rows, because of similarity. Likewise, when you
watch a football game, you use the colors of the uniforms to group the players into
two teams because of similarity, even when they are mixed together during a play. You
can also hear the law of similarity echoed in the old proverb “Birds of a feather flock
together,” which is a commentary not only on avian behavior but also on the assump-
tions we make about perceptual grouping. Any such tendency to perceive things as
belonging together because they share common features reflects the law of similarity.
Now, suppose that, on one drowsy morning, you mistakenly put on two different-
colored socks because they were together in the drawer and you assumed that they
were a pair. Your mistake was merely Wertheimer’s law of proximity (nearness) at work.
The proximity principle says that we tend to group things together that are near each
other, as you can see in the pairings of the Xs with the Os in Figure 3.23B. On the level
of social perception, your parents were invoking the law of proximity when they cau-
tioned you, “You’re known by the company you keep.”
We can see the Gestalt law of continuity in Figure 3.23C, where the straight line
appears as a single, continuous line, even though the curved line repeatedly cuts
through it. In general, the law of continuity says that we prefer smoothly con-
nected and continuous figures to disjointed ones. Continuity also operates in the
realm of social perception, where we commonly make the assumption of continuity
in the personality of an individual whom we haven’t seen for some
time. So, despite interruptions in our contact with that person, we
will expect to find continuity—to find him or her to be essentially
the same person we knew earlier.
There is yet another form of perceptual grouping—one that we
cannot illustrate in the pages of a book because it involves motion.
But you can easily conjure up your own image that exemplifies the
law of common fate: Imagine a school of fish, a gaggle of geese, or a
uniformed marching band. When visual elements (the individual fish,
geese, or band members) are moving together, you perceive them as a
single Gestalt.
According to the Gestalt perspective, then, each of these exam-
ples of perceptual grouping illustrates the profound idea that our
perceptions reflect innate patterns in the brain. These inborn mental
processes, in a top-down fashion, determine the organization of the
individual parts of the percept, just as mountains and valleys deter-
mine the course of a river. Moreover, the Gestalt psychologists sug-
gested, the laws of perceptual grouping exemplify a more general
principle known as the law of Prägnanz (“meaningfulness”). This prin-
ciple states that we perceive the simplest pattern possible—the percept
requiring the least mental effort. The most general of all the Gestalt
principles, Prägnanz (pronounced PRAYG-nonce) has also been called
the minimum principle of perception. The law of Prägnanz is what
makes proofreading so hard to do, as you will find when you examine
Figure 3.24.
Learning-Based Inference: The Nurture of Perception In 1866,
Hermann von Helmholtz pointed out the important role of learning (or
nurture) in perception. His theory of learning-based inference emphasized
how people use prior learning to interpret new sensory information.
Based on experience, then, the observer makes inferences—guesses or
predictions—about what the sensations mean. This theory explains, for
laws of perceptual grouping The Gestalt
principles of similarity, proximity, continuity, and common
fate. These “laws” suggest how our brains prefer to group
stimulus elements together to form a percept (Gestalt).
law of similarity The Gestalt principle that we
tend to group similar objects together in our perceptions.
law of proximity The Gestalt principle that we
tend to group objects together when they are near each
other. Proximity means “nearness.”
A
BIRD
IN THE
THE HAND
FIGURE 3.24
A Bird in the . . .
We usually see what we expect to
see—not what is really there. Look
again.
Quickly scan this photo. Then look away and describe as
much as you recall. Next, turn to page 124 to learn what
you may or may not have seen.

What Is the Relationship between Sensation and Perception? 121
example, why you assume a birthday party is in progress when you see lighted candles
on a cake: You have learned to associate cakes, candles, and birthdays.
Ordinarily, such perceptual inferences are fairly accurate. On the other hand, we
have seen that confusing sensations and ambiguous arrangements can create perceptual
illusions and erroneous conclusions. Our perceptual interpretations are, in effect,
hypotheses about our sensations. For example, even babies come to expect that faces
will have certain features in fixed arrangements (pair of eyes above nose, mouth below
nose, etc.). In fact, our expectations about faces in their usual configuration are so
thoroughly ingrained that we fail to “see” facial patterns that violate our expectations,
particularly when they appear in an unfamiliar orientation. When you look at the two
inverted portraits of Beyoncé (Figure 3.25), do you detect any important differences
between them? Turn the book upside down for a surprise.
What, according to the theory of learning-based inference, determines how suc-
cessful we will be in forming an accurate percept? The most important factors in-
clude the context, our expectations, and our perceptual set. We will see that each of
these involves a way of narrowing our search of the vast store of concepts in long-
term memory.
Context and Expectations Once you identify a context, you form expectations about
what persons, objects, and events you are likely to experience (Biederman, 1989). To
see what we mean, take a look at the following:
It says THE CAT, right? Now look again at the middle letter of each word. Physically,
these two letters are exactly the same, yet you perceived the first as an H and the sec-
ond as an A. Why? Clearly, your perception was affected by what you know about
words in English. The context provided by T__E makes an H highly likely and an A
unlikely, whereas the reverse is true of the context of C__T (Selfridge, 1955).
Here’s a more real-world example: You have probably had difficulty recogniz-
ing people you know in situations where you didn’t expect to see them, such as
in a different city or a new social group. The problem, of course, is not that they
looked different but that the context was unusual: You didn’t expect them to be
there. Thus, perceptual identification depends on context and expectations as well as
on an object’s physical properties.
Perceptual Set Another way learning serves as a platform from which context and
expectation exert an influence on perception involves perceptual set—which is closely
related to expectation. Under the influence of perceptual set, we have a readiness to
notice and respond to certain stimulus cues—like a sprinter anticipating the starter’s
pistol. In general, perceptual set involves a focused alertness for a particular stimulus
in a given context. For example, a new mother is set to hear the cries of her child.
Likewise, if you drive a sporty red car, you probably know how the highway patrol
has a perceptual set to notice speeding sporty red cars.
Often, a perceptual set leads you to transform an ambiguous stimulus into the one
you were expecting. To experience this yourself, read quickly through the series of
words that follow in both rows:
FOX; OWL; SNAKE; TURKEY; SWAN; D?CK
BOB; RAY; DAVE; BILL; TOM; D?CK
Notice how the words in the two rows lead you to read D?CK differently in each row.
The meanings of the words read prior to the ambiguous stimulus create a perceptual
law of common fate The Gestalt principle that
we tend to group similar objects together that share a
common motion or destination.
law of Prägnanz The most general Gestalt prin-
ciple, which states that the simplest organization, requir-
ing the least cognitive effort, will emerge as the figure.
Prägnanz shares a common root with pregnant, and so it
carries the idea of a “fully developed figure.” That is, our
perceptual system prefers to see a fully developed Gestalt,
such as a complete circle—as opposed to a broken circle.
learning-based inference The view that per-
ception is primarily shaped by learning (or experience),
rather than by innate factors.
perceptual set Readiness to detect a particular
stimulus in a given context—as when a person who is
afraid interprets an unfamiliar sound as a threat.
law of continuity The Gestalt principle that we
prefer perceptions of connected and continuous figures
to disconnected and disjointed ones.
FIGURE 3.25
Two Perspectives on Beyoncé
Although one of these photos clearly
has been altered, they look similar
when viewed this way. However, turn
the book upside down and look again.

122 C H A P T E R 3 Sensation and Perception
set. Words that refer to animals create a perceptual set that influences you to read
D?CK as “DUCK.” Names create a perceptual set leading you to see D?CK as DICK.
Yet another illustration of perceptual set appears in the Do It Yourself! box “You See
What You’re Set to See.”
Cultural Influences on Perception Which of the following three items go together:
chicken, cow, grass? If you are American, you are likely to group chicken and cow,
because they are both animals. But if you are Chinese, you are more likely to put the
latter two together, because cows eat grass. In general, says cross-cultural psychologist
Richard Nisbett, Americans tend to put items in categories by abstract type
rather than by relationship or function (Winerman, 2006d).
Nisbett and his colleagues have also found that East Asians typically per-
ceive in a more holistic fashion than do Americans (Nisbett, 2003; Nisbett &
Norenzayan, 2002). That is, the Asians pay more attention to, and can later
recall more detail about, the context than do Americans. (This is true, inciden-
tally, even if the American is of Chinese ancestry.) Specifically, when looking at
a scene, people raised in America tend to spend more time scanning the “fig-
ure,” while those raised in China usually focus more on details of the “ground”
(Chua et al., 2005). “The Americans are more zoom and the East Asians are
more panoramic,” says neuroscientist Denise Park (Goldberg, 2008). Such dis-
tinctions are now even showing up as subtle differences on scans comparing
brain activity of Asians and Americans on simple perceptual judgment tasks
(Hedden et al., 2008).
Cross-cultural psychologists have pointed to still other cultural differ-
ences in perception (Segall et al., 1999). Consider, for example, the famous
Ponzo illusion, based on linear perspective depth cues (see Figure 3.26). In
your opinion, which bar is longer: the one on top (marked A) or the one
on the bottom (marked B)? In actuality, both bars are the same length. (If
you’ve developed a skeptical scientific attitude, you’ll measure them!) Re-
search shows, however, that responses to these figures depend strongly on
culture-related experiences. Most readers of this book will report that the
top bar appears longer than the bottom bar, yet people from some cultural
backgrounds are not so easily fooled.
Why the difference? The world you have grown up in probably included
many structures featuring parallel lines that seemed to converge in the dis-
tance: railroad tracks, long buildings, highways, and tunnels. Such experi-
ences leave you vulnerable to images, such as the Ponzo illusion, in which
cues for size and distance are unreliable.
But what about people from cultures where individuals have had far less
experience with this cue for distance? Research on this issue has been carried
YOU SEE WHAT YOU’RE SET TO SEE
Labels create a context that can impose a
perceptual set for an ambiguous figure. Have
a friend look carefully at the picture of the
“young woman” in image (A) of the accompa-
nying figure, and have another friend exam-
ine the “old woman” in image (B). (Cover the
other pictures while they do this.) Then have
them look together at image (C). What do
they see? Each will probably see something
different, even though it’s the same stimulus
pattern. Prior exposure to the picture with a
specific label will usually affect a person’s
perception of the ambiguous figure.
(A) A Young Woman (B) An Old Woman (C) Now what do you see?
A
B
FIGURE 3.26
The Ponzo Illusion
The two white bars superimposed on the railroad
track are actually identical in length. Because A ap-
pears farther away than B, we perceive it as longer.

What Is the Relationship between Sensation and Perception? 123
out on the Pacific island of Guam, where there are no Ponzolike railroad tracks (Bris-
lin, 1974, 1993). There, too, the roads are so winding that people have few opportu-
nities to see roadsides “converge” in the distance. People who have spent their entire
lives on Guam, then, presumably have fewer opportunities to learn the strong percep-
tual cue that converging lines indicate distance.
And, sure enough—just as researchers had predicted—people who had lived all their
lives on Guam were less influenced by the Ponzo illusion than were respondents from
the mainland United States. That is, they were less likely to report that the top line in the
figure was longer. These results strongly support the argument that people’s experiences
affect their perceptions—as Helmholz had theorized.
Depth Perception: Nature or Nurture? Now that we have looked at two contrast-
ing approaches to perception—Gestalt theory, which emphasizes nature, and learning-
based inference, which emphasizes nurture—let’s see how each explains a
classic problem in psychology: depth perception. Are we born with the ability
to perceive depth, or must we learn it? Let’s look at the evidence.
Bower (1971) found evidence of depth perception in infants only 2 weeks
old. By fitting his subjects with 3-D goggles, Bower produced powerful virtual
reality images of a ball moving about in space. When the ball image suddenly
appeared to move directly toward the infant’s face, the reaction was increased
heart rate and obvious anxiety. This suggests that some ability for depth per-
ception is probably inborn or heavily influenced by genetic programming that
unfolds in the course of early development.
Although depth perception appears early in human development, the
idea of being cautious when there is danger of falling seems to develop later
in infancy. In a famous demonstration, psychologists Eleanor Gibson and
Richard Walk placed infants on a Plexiglas-topped table that appeared to drop
off sharply on one end. (See the accompanying photo.) Reactions to the visual
cliff occurred mainly in infants older than 6 months—old enough to crawl.
Most readily crawled across the “shallow” side of the table, but they were
reluctant to go over the “edge” of the visual cliff—indicating not only that they
could perceive depth but also that they associated the drop-off with danger
(Gibson & Walk, 1960). Developmental psychologists believe that crawling and depth
perception are linked in that crawling helps infants develop their understanding of the
three-dimensional world.
Digging deeper into the problem of depth perception, we find that our sense of
depth or distance relies on multiple cues. We can group these depth cues in two catego-
ries, either binocular cues or monocular cues.
Binocular Cues Certain depth cues, the binocular cues, depend on the use of two eyes.
You can demonstrate this to yourself: Hold one finger about 6 inches from your eyes
and look at it. Now move it about a foot farther away. Do you feel the change in your
eye muscles as you focus at different distances? This feeling serves as one of the main
cues for depth perception when looking at objects that are relatively close. The term
for this, binocular convergence, suggests how the lines of vision from each eye con-
verge at different angles on objects at different distances.
A related binocular depth cue, retinal disparity, arises from the difference in
perspectives of the two eyes. To see how this works, again hold a finger about 12
inches from your face and look at it alternately with one eye and then with the
other. Notice how you see a different view of your finger with each eye. Because
we see greater disparity when looking at nearby objects than we do when viewing
distant objects, these image differences coming from each eye provide us with depth
information.
We can’t say for sure whether the binocular cues are innate or learned. What we
can say is that they rely heavily on our biology: a sense of eye muscle movement and
the physically different images on the two retinas. The monocular cues, however, pres-
ent a very different picture.
binocular cues Information taken in by both
eyes that aids in depth perception, including binocular
convergence and retinal disparity.
Apprehension about the “visual cliff” shows that
infants make use of distance clues. This ability de-
velops at about the same time an infant is learning
to crawl.
Read t
at MyPsychLab
about Cultural Differences in
Interpretation of Symbols

124 C H A P T E R 3 Sensation and Perception
Monocular Cues for Depth Perception Not all cues for depth perception require both
eyes. A one-eyed pilot we know, who manages to perceive depth well enough to ma-
neuver the airplane safely during takeoffs and landings, is proof that one-eye cues con-
vey a great deal of depth information. Here are some of the monocular cues that a
one-eyed pilot (or a two-eyed pilot, for that matter) could learn to use while flying:
• If two objects that are assumed to be the same size cast different-sized images on
the retina, observers usually judge them to lie at different distances. So a pilot fly-
ing low can learn to use the relative size of familiar objects on the ground as a cue
for depth and distance. Because of this cue, automakers who install wide-angle
rear-view mirrors always inscribe the warning on them, “Objects in the mirror are
closer than they appear.”
• If you have ever looked down a long, straight railroad track, you know that the
parallel rails seem to come together in the distance—as we saw in the Ponzo illusion
(p. 122). Likewise, a pilot approaching a runway for landing sees the runway as being
much wider at the near end than at the far end. Both examples illustrate how linear
perspective, the apparent convergence of parallel lines, can serve as a depth cue.
• Lighter-colored objects seem closer to us, and darker objects seem farther away.
Thus, light and shadow work together as a distance cue. You will notice this the
next time you drive your car at night with the headlights on: Objects that reflect
the most light appear to be nearer than more dimly lit objects in the distance.
• We assume that closer objects will cut off our vision of more distant objects
behind them, a distance cue known as interposition. So we know that partially
hidden objects are more distant than the objects that hide them. You can see this
effect right in front of you now, as your book partially obscures the background,
which you judge to be farther away.
• As you move, objects at different distances appear to move through your field
of vision at a different rate or with a different relative motion. Look for this one
from your car window. Notice how the power poles or fence posts along the road-
side appear to move by at great speed, while more distant objects stay in your field
of view longer, appearing to move by more slowly. With this cue, student pilots
learn to set up a glide path to landing by adjusting their descent so that the end of
the runway appears to stay at a fixed spot on the windshield while more distant
points appear to move upward and nearer objects seem to move downward.
• Haze or fog makes objects in the distance look fuzzy, less distinct, or invisible, creat-
ing another learned distance cue called atmospheric perspective. In the accompanying
photo, you can see that more distant buildings lack clarity through the Los Angeles
smog. At familiar airports, most pilots have identified a landmark three miles away. If
they cannot see the landmark, they know that they must fly by relying on instruments.
So which of the two theories about perception that we have been discussing—
Helmholtz’s learning theory or the Gestaltists’ innate theory—best accounts for depth
perception? Both of them! That is, depth and distance perception—indeed, all our
perceptual processes—show the influence of both nature and nurture.
Seeing and Believing
If you assume, as most people do, that your senses give you an accurate and undis-
torted picture of the outside world, you are mistaken (Segall et al., 1990). We hope
that the illusions presented in this chapter will help make the point. We also hope that
the chapter has helped you realize that people see the world through the filter of their
own perceptions—and that marketing and politics depend on manipulating our per-
ceptions (think iPhones, Droids, and Blackberries).
Magicians are also experts in manipulating perceptions—and so perceptual scien-
tists are making them partners in perceptual research (Hyman, 1989; Martinez-Conde &
Macknik, 2008; Sanders, 2009). The results include discoveries about change blindness,
inattentional blindness, and brain modules involved in both attention and perception.
monocular cues Information about depth that
relies on the input of just one eye—includes relative
size, light and shadow, interposition, relative motion,
and atmospheric perspective.
Haze, fog, or air pollution makes distant
objects less distinct, creating atmo-
spheric perspective, which acts as a
distance cue. Even the air itself provides
a cue for distance by giving far-away
objects a bluish cast.
Did you see a woman committing suicide
in the photo on page 120? Most people
have difficulty identifying the falling
woman in the center of the photo because
of the confusing background and because
they have no perceptual schema that
makes them expect to see a person posi-
tioned horizontally in midair.

What Is the Relationship between Sensation and Perception? 125
Unlike magicians, however, perceptual scientists are happy to reveal how sensation and
perception play tricks on us all. (Incidentally, a magician friend of ours warns that smart
people are the easiest ones to fool. So watch out!)
We hope that this chapter has shaken your faith in your senses and perceptions . . .
just a bit. To drive the point home, consider this statement (which, unfortunately, was
printed backward):
.rat eht saw tac ehT
Please turn it around in your mind: What does it say? At first most people see a sen-
sible sentence that says, “The cat saw the rat.” But take another look. The difficulty lies
in the power of expectations to shape your interpretation of stimulation.
This demonstration illustrates once again that we don’t merely sense the world as it
is; we perceive it. The goal of the process by which stimulation becomes sensation and,
finally, perception is to find meaning in our experience. But it is well to remember that
we impose our own meanings on sensory experience.
Differences in the ways we interpret our experiences explain why two people can
look at the same sunset, the same presidential candidates, or the same religions and
perceive them so differently. Perceptual differences make us unique individuals. An old
Spanish proverb makes the point elegantly:
En este mundo traidor In this treacherous world
No hay verdad ni mentira; There is neither truth nor lie;
Todo es según el color All is according to the color
Del cristál con que se mira. Of the lens through which we spy.
With this proverb in mind, let’s return one more time to the problem with which
we began the chapter—and in particular to the question of whether the world looks
(feels, tastes, smells . . .) the same to different people. We have every reason to suspect
that we all (with some variation) sense the world in roughly the same way. But be-
cause we attach different meanings to our sensations, it is clear that people perceive
the world in many different ways—with, perhaps, as many differences as there are
people.
PSYCHOLOGY MATTERS
Using Psychology to Learn Psychology
One of the most mistaken notions about studying and learning is that students should
set aside a certain amount of time for study every day. This is not to suggest that you
shouldn’t study regularly. Rather, it is to say that you shouldn’t focus on merely put-
ting in your time. So where should you place your emphasis? (And what does this have
to do with perceptual psychology?)
Recall the concept of Gestalt, the idea of the meaningful pattern, discussed earlier in
this chapter. The Gestalt psychologists taught that we have an innate tendency to under-
stand our world in terms of meaningful patterns. Applied to your studying, this means that
your emphasis should be on finding meaningful patterns—Gestalts—in your course work.
In this chapter, for example, you will find that your authors have helped you by divid-
ing the material into three major sections. You can think of each section as a conceptual
Gestalt built around a Core Concept that ties it together and gives it meaning. We suggest
that you organize your study of psychology around one of these meaningful units of ma-
terial. That is, identify a major section of your book and study that until it makes sense.
To be more specific, you might spend an hour or two working on the first section of this
chapter, where you would not only read the material but also connect each boldfaced term
to the Core Concept. For example, what does the difference threshold have to do with the
idea that the brain senses the world through neural messages? (Sample brief answer: The
brain is geared to detect changes or differences that are conveyed to it in the form of neural
Most of us assume that our senses
give us an accurate picture of the
world. This helps magicians like
Lance Burton fool us with perceptual
illusions.
about Extrasensory Perception atRead
MyPsychLab

126 C H A P T E R 3 Sensation and Perception
impulses.) We suggest that you do the same thing with each of the other boldfaced terms in
the chapter. The result will be a deeper understanding of the material. In perceptual terms,
you will be constructing a meaningful pattern—a Gestalt—around the Core Concept.
You can do that only by focusing on meaningful units of material rather than on
the clock.
CRITICAL THINKING APPLIED
Subliminal Perception and Subliminal Persuasion
Could extremely weak stimulation—stimulation that you don’t even notice—affect your attitudes, opinions, or be-
havior? We know that the brain does a lot of information
processing outside of awareness. So the notion that your
sensory system can operate below the level of awareness is
the basis for the industry that sells “subliminal” recordings
touted as remedies for obesity, shoplifting, smoking, and low
self-esteem. The same notion also feeds the fear that certain
musical groups imbed hidden messages in their recordings or
that advertisers may be using subliminal messages to influ-
ence our buying habits and, perhaps, our votes (Vokey, 2002).
What Are the Critical Issues?
People are always hoping for a bit of magic. But before you put
your money in the mail for that subliminal weight-loss CD, let’s
identify what exactly we’re talking about—and what we’re not
talking about. If subliminal persuasion works as claimed, then
it must work on groups of people—a mass audience—rather

than just on individuals. It also means that a persuasive mes-
sage can change the behavior of large numbers of people, even
though no one is aware of the message. The issue is not whether
sensory and perceptual processing can occur outside of aware-
ness. The issue is whether subliminal messages can effect a sub-
stantial change in people’s attitudes, opinions, and behaviors.
Fame, Fortune, Fraud, and Subliminal Perception There
is always a possibility of fraud when fortune or fame is
involved, which is certainly the case with claims of amazing
powers—such as persuasion through subliminal perception. This
should cue us to ask: What is the source of claims that sublimi-
nal persuasion techniques work? That question leads us to an
advertising executive, one James Vicary, who dramatically an-
nounced to the press some years ago that he had discovered an
irresistible sales technique, now known as “subliminal advertis-
ing.” Vicary said that his method consisted of projecting very
brief messages on the screen of a movie theater, urging the audi-
ence to “Drink Coke” and “Buy popcorn.” He claimed that the
subliminal perception The process by which a
stimulus that is below the awareness threshold can be
sensed and interpreted outside of consciousness.
Check Your Understanding
1. APPLICATION: Give an example, from your own experience, of
top-down processing.
2. RECALL: Our brains have specialized cells, known as
, dedicated to identifying stimulus properties such as
length, slant, color, and boundary.
3. RECALL: What do perceptual constancies do for us?
4. RECALL: What two basic perceptual properties seem to reverse or
alternate in the faces/vase image (in Figure 3.17A)?
5. APPLICATION: When two close friends are talking, other people
may not be able to follow their conversation because it has
many gaps that the friends can mentally fill in from their shared
experience. Which Gestalt principle is illustrated by the friends’
ability to fill in these conversational gaps?
6. UNDERSTANDING THE CORE CONCEPT: Which of the
following best illustrates the idea that perception is not an exact
internal copy of the world?
a. the sound of a familiar tune
b. the Ponzo illusion
c. a bright light
d. jumping in response to a pinprick
Answers 1. Your example should involve perception based on expectations, motives, emotions, or mental images—such as seeing a friend’s face
in a crowd or making sense of an unexpected sound in the house at night. 2. feature detectors 3. Perceptual constancies allow us to identify and
track objects under a variety of conditions, such as changes in illumination or perspective. 4. Figure and ground 5. Closure 6. b—because, of all the
choices listed, the Ponzo illusion involves the most extensive perceptual interpretation.
Study and Review at MyPsychLab

What Is the Relationship between Sensation and Perception? 127
ads presented ideas so fleetingly that the conscious mind could
not perceive them—yet, he said, the messages would still lodge
in the unconscious mind, where they would work on the view-
ers’ desires unnoticed. Vicary also boasted that sales of Coca-
Cola and popcorn had soared at a New Jersey theater where he
tested the technique.
The public was both fascinated and outraged. Subliminal
advertising became the subject of intense debate. People wor-
ried that they were being manipulated by powerful psycho-
logical forces without their consent. As a result, laws were
proposed to quash the practice. But aside from the hysteria,
was there any real cause for concern? To answer that ques-
tion, we must ask: What is the evidence?
Examining the Evidence Let’s first see what the psycholog-
ical science of perceptual thresholds can tell us. As you will re-
call, a threshold refers to the minimum amount of stimulation
necessary to trigger a response. The word subliminal means
“below the threshold” (limen = threshold). In the language of
perceptual psychology, subliminal more specifically refers to
stimuli lying near the absolute threshold. Such stimuli may, in
fact, be strong enough to affect the sense organs and to enter
the sensory system without causing conscious awareness of the
stimulus. But the real question is this: Can subliminal stimuli in
this range influence our thoughts and behavior?
Several studies have found that subliminal words flashed
briefly on a screen (for less than 1/100 second) can “prime”
a person’s later responses (Merikle & Reingold, 1990). For
example, can you fill in the following blanks to make a word?
S N _ _ _ E L
If you had been subliminally primed by a brief presenta-
tion of the appropriate word or picture, it would be more
likely that you would have found the right answer, even
though you were not aware of the priming stimulus. So does
the fact that subliminal stimulation can affect our responses
on such tasks mean that subliminal persuasion really works?
Of course, priming doesn’t always work: It merely in-
creases the chances of getting the “right” answer. The answer
to the problem, by the way, is “snorkel.” And were you aware
that we were priming you with the photo, to the right, of a
snorkeler? If you were, it just goes to show that sometimes
people do realize when they are being primed.
What Conclusions Can We Draw?
Apparently people do perceive stimuli below the absolute
threshold, under circumstances such as the demonstration
above (Greenwald et al., 1996; Reber, 1993). Under very
carefully controlled conditions, subliminal perception is a
fact. But here is the problem for would-be subliminal adver-
tisers who would attempt to influence us in the uncontrolled
world outside the laboratory: Different people have thresh-
olds at different levels. So what might be subliminal for me
could well be supraliminal (above the threshold) for you.
Consequently, the would-be subliminal advertiser runs the
risk that some in the audience will notice—and perhaps be
angry about—a stimulus aimed slightly below the average
person’s threshold. In fact, no controlled research has ever
shown that subliminal messages delivered to a mass audience
can influence people’s buying habits or voting patterns.
And what about those subliminal recordings that some
stores play to prevent shoplifting? Again, no reputable study
has ever demonstrated their effectiveness. A more likely expla-
nation for any decrease in shoplifting attributed to these mes-
sages lies in increased vigilance from employees who know
that management is worried about shoplifting. The same goes
for the tapes that claim to help you quit smoking, lose weight,
become wildly creative, or achieve other dozens of elusive
dreams. In a comprehensive study of subliminal self-help
techniques, the U.S. Army found all to be without foundation
(Druckman & Bjork, 1991). The simplest explanation for re-
ports of success lies in the purchasers’ expectations and in the
need to prove that they did not spend their money foolishly.
And finally, to take the rest of the worry out of subliminal
persuasion, you should know one more bit of evidence. James
Vicary eventually admitted that his claims for subliminal ad-
vertising were a hoax (Druckman & Bjork, 1991).
So, using our previous SNORKEL example, could you use
what you know about the Gestalt principle of closure to get
theatergoers to think about popcorn?
This photo carries a subliminal message, explained in the text.

• The brain does not sense the external world directly. The sense
organs transduce stimulation and deliver stimulus information
to the brain in the form of neural impulses. Our sensory
experiences are, therefore, what the brain creates from the
information delivered in these neural impulses.
CHAPTER PROBLEM: Is there any way to tell whether the
world we “see” in our minds is the same as the external world—and
whether we see things as most others do?
• Different people probably have similar sensations in response
to a stimulus because their sense organs and parts of the brain
they use in sensation are similar.
• People differ, however, in their perceptions, because they draw
on different experiences to interpret their sensations.
CHAPTER SUMMARY
3.1 How Does Stimulation Become
Sensation?
Core Concept 3.1 The brain senses the world indirectly
because the sense organs convert stimulation into the
language of the nervous system: neural messages.
The most fundamental step in sensation involves the trans-
duction by the sense organs of physical stimuli into neural
messages, which are sent onward in the sensory pathways
to the appropriate part of the brain for further process-
ing. Not all stimuli become sensations, because some fall
below the absolute threshold. Further, changes in stimula-
tion are noticed only if they exceed the difference threshold.
Classical psychophysics focused on identifying thresholds
for sensations and for just-noticeable differences, but a
newer approach, called signal detection theory, explains sen-
sation as a process involving context, physical sensitivity,
and judgment. We should consider our senses to be change
detectors. But because they accommodate to unchanging
stimulation, we become less and less aware of constant
stimulation.
absolute threshold (p. 91)
difference threshold (p. 92)
perception (p. 89)
sensation (p. 88)
sensory adaptation (p. 93)
signal detection theory (p. 93)
transduction (p. 90)
Weber’s law (p. 92)
3.2 How Are the Senses Alike?
How Are They Different?
Core Concept 3.2 The senses all operate in much the
same way, but each extracts different information and sends it
to its own specialized sensory processing region in the brain.
All the senses involve transduction of physical stimuli into
nerve impulses. Thus, our sensations are not properties of
the original stimulus, but rather are creations of the brain.
In vision, photoreceptors in the retina transduce light waves
into neural codes, which retain frequency and amplitude
information. This visual information is then transmitted by
the optic nerve to the brain’s occipital lobe, which converts
the neural signals into sensations of color and brightness.
Both the trichromatic theory and the opponent process theory
are required to explain how visual sensations are extracted.
Vision makes use of only a tiny “window” in the electromag-
netic spectrum.
In the ear, sound waves in the air are transduced into neural
energy in the cochlea and then sent on to the brain’s temporal
lobes, where frequency and amplitude information are con-
verted to sensations of pitch, loudness, and timbre.
Other senses include position and movement (the
vestibular and kinesthetic senses), smell, taste, the skin senses
(touch, pressure, and temperature), and pain. Like vision
and hearing, these other senses are especially attuned to
detect changes in stimulation. Further, all sensations are
carried to the brain by neural impulses, but we experience
different sensations because the impulses are processed
by different sensory regions of the brain. In some people,
sensations cross sensory domains. Studies suggest that
synesthesia involves communication between sensory areas
of the brain that lie close together. This seems to occur more
often in highly creative people.
The experience of pain can be the result of intense stimu-
lation in any of several sensory pathways. While we don’t
completely understand pain, the gate-control theory explains
how pain can be suppressed by competing sensations or
other mental processes. Similarly, the ideal analgesic—one
without unwanted side effects—has not been discovered, al-
though the placebo effect works exceptionally well for some
people.
Listen at MyPsychLabto an audio file of your chapter
128 C H A P T E R 3 Sensation and Perception

Chapter Summary 129
afterimages (p. 99)
amplitude (p. 101)
basilar membrane (p. 102)
blind spot (p. 96)
brightness (p. 98)
cochlea (p. 102)
color (p. 98)
color blindness (p. 100)
cones (p. 96)
electromagnetic spectrum (p. 98)
fovea (p. 96)
frequency (p. 101)
gate-control theory (p. 109)
gustation (p. 106)
kinesthetic sense (p. 105)
loudness (p. 103)
olfaction (p. 105)
opponent-process theory (p. 99)
optic nerve (p. 96)
percept (p. 112)
pheromones (p. 105)
photoreceptors (p. 95)
pitch (p. 102)
placebo (p. 110)
placebo effect (p. 110)
retina (p. 95)
rods (p. 95)
skin senses (p. 108)
synesthesia (p. 108)
timbre (p. 103)
trichromatic theory (p. 99)
tympanic membrane (p. 101)
vestibular sense (p. 105)
visible spectrum (p. 98)
3.3 What Is the Relationship between
Sensation and Perception?
Core Concept 3.3 Perception brings meaning to
sensation, so perception produces an interpretation of the
world, not a perfect representation of it.
Psychologists define perception as the stage at which mean-
ing is attached to sensation. Visual identification of objects
involves feature detectors in the what pathway that projects to
the temporal lobe. The where pathway, projecting to the parietal
lobe, involves the location of objects in space. The disorder
known as blindsight occurs because the where pathway can
operate outside of consciousness. We also derive meaning from
bottom-up stimulus cues picked up by feature detectors and
from top-down processes, especially those involving expecta-
tions. What remains unclear is how the brain manages to com-
bine the output of many sensory circuits into a single percept:
This is called the binding problem. By studying such perceptual
phenomena as illusions, perceptual constancies, change blindness,
and inattentional blindness, researchers can learn about the fac-
tors that influence and distort the construction of perceptions.
Illusions demonstrate that perception does not necessarily
form an accurate representation of the outside world.
Perception has been explained by theories that differ in their
emphasis on the role of innate brain processes versus learning—
nature versus nurture. Gestalt psychology emphasizes innate fac-
tors that help us organize stimulation into meaningful patterns.
In particular, the Gestaltists have described the processes that
help us distinguish figure from ground, to identify contours and
apply closure, and to group stimuli according to similarity, prox-
imity, continuity, and common fate. Some aspects of depth percep-
tion, such as retinal disparity and convergence, may be innate
as well. The theory of learning-based inference also correctly
points out that perception is influenced by experience, such as
context, perceptual set, and culture. Many aspects of depth per-
ception, such as relative motion, linear perspective, and atmo-
spheric perspective, seem to be learned.
Despite all we know about sensation and perception,
many people uncritically accept the evidence of their senses
(and perceptions) at face value. This allows magicians, politi-
cians, and marketers an opening through which they can ma-
nipulate our perceptions and, ultimately, our behavior.
ambiguous figures (p. 115)
binding problem (p. 113)
binocular cues (p. 123)
blindsight (p. 112)
bottom-up processing (p. 113)
change blindness (p. 114)
closure (p. 119)
feature detectors (p. 112)
figure (p. 118)
Gestalt psychology (p. 118)
ground (p. 118)
illusion (p. 114)
inattentional blindness (p. 114)
law of common fate (p. 121)
law of continuity (p. 121)
law of Prägnanz (p. 121)
law of proximity (p. 120)
law of similarity (p. 120)
laws of perceptual grouping (p. 120)
learning-based inference (p. 121)
monocular cues (p. 124)
percept (p. 112)
perceptual constancy (p. 113)
perceptual set (p. 121)
top-down processing (p. 113)
what pathway (p. 112)
where pathway (p. 112)
CRITICAL THINKING APPLIED
claims to the contrary, there is no evidence that techniques of
subliminal persuasion are effective in persuading a mass audi-
ence to change their attitudes or behaviors.
Subliminal Perception and Subliminal Persuasion
Subliminal messages, in the form of priming, have been
shown to affect an individual’s responses on simple tasks un-
der carefully controlled conditions. Yet, despite advertising

130 C H A P T E R 3 Sensation and Perception
DISCOVERING PSYCHOLOGY VIEWING GUIDE
Watch the following video by logging into MyPsychLab (www.mypsychlab.com).
After you have watched the video, answer the questions that follow.
PROGRAM 7: SENSATION AND PERCEPTION
Program Review
c. He will accurately perceive the ball’s position.
d. It is impossible to predict an individual’s reaction in this
situation.
8. Imagine that a small dog is walking toward you. As the dog gets
closer, the image it casts on your retina
a. gets larger. c. gets smaller.
b. gets darker. d. stays exactly the same size.
9. Imagine the same small dog walking toward you. You know that
the dog’s size is unchanged as it draws nearer. A psychologist
would attribute this to
a. perceptual constancy. c. contrast effects.
b. visual paradoxes. d. threshold differences.
10. Which of the following best illustrates that perception is an active
process?
a. bottom-up processing c. top-down processing
b. motion parallax d. parietal senses
11. The program shows a drawing that can be seen as a rat or as a
man. People were more likely to identify the drawing as a man
if they
a. were men themselves.
b. had just seen pictures of people.
c. were afraid of rats.
d. looked at the picture holistically rather than analytically.
12. Where is the proximal stimulus found?
a. in the outside world c. in the occipital lobe
b. on the retina d. in the thalamus
13. How is visual information processed by the brain?
a. It’s processed by the parietal lobe, which relays the informa-
tion to the temporal lobe.
b. It’s processed entirely within the frontal lobe.
c. It’s processed by the occipital lobe, which projects to the
thalamus, which projects to a succession of areas in the
cortex.
d. If the information is abstract, it’s processed by the cortex; if
it’s concrete, it’s processed by the thalamus.
1. Imagine that a teaspoon of sugar is dissolved in 2 gallons of water.
Rita can detect this level of sweetness at least half the time. This
level is called the
a. distal stimulus. c. response bias.
b. perceptual constant. d. absolute threshold.
2. What is the job of a receptor?
a. to transmit a neural impulse
b. to connect new information with old information
c. to detect a type of physical energy
d. to receive an impulse from the brain
3. In what area of the brain is the visual cortex located?
a. in the front c. in the back
b. in the middle d. under the brain stem
4. What is the function of the thalamus in visual processing?
a. It relays information to the cortex.
b. It rotates the retinal image.
c. It converts light energy to a neural impulse.
d. It makes sense of the proximal stimulus.
5. David Hubel discusses the visual pathway and the response to a
line. The program shows an experiment in which the response to a
moving line changed dramatically with changes in the line’s
a. thickness. c. speed.
b. color. d. orientation.
6. Misha Pavel used computer graphics to study how
a. we process visual information.
b. rods differ from cones in function.
c. we combine information from different senses.
d. physical energy is transduced in the visual system.
7. Imagine that a baseball player puts on special glasses that shift
his visual field up 10 degrees. When he wears these glasses,
the player sees everything higher than it actually is. After some
practice, the player can hit with the glasses on. What will happen
when the player first tries to hit with the glasses off?
a. He will think that the ball is lower than it is.
b. He will think that the ball is higher than it is.

www.mypsychlab.com

Discovering Psychology Viewing Guide 131
14. Which of the following is true about the proximal stimulus in
visual perception?
a. It’s identical to the distal stimulus because the retina pro-
duces a faithful reproduction of the perceptual world.
b. It’s upside-down, flat, distorted, and obscured by blood vessels.
c. It’s black and white and consists of very sparse information
about horizontal and vertical edges.
d. It contains information about the degree of convergence of the
two eyes.
15. Which of the following is an example of pure top-down processing
(i.e., requires no bottom-up processing)?
a. hallucinating
b. understanding someone else’s speech when honking horns are
obscuring individual sounds
c. perceiving a circular color patch that has been painted onto a
canvas
d. enjoying a melody
16. Which sensory information is not paired with the cortical lobe that
is primarily responsible for processing it?
a. visual information, occipital lobe
b. speech, frontal lobe
c. body senses, parietal lobe
d. hearing, central sulcus lobe
17. When your eyes are shut, you cannot
a. hallucinate.
b. use contextual information from other senses to make infer-
ences about what’s there.
c. transform a distal visual stimulus into a proximal stimulus.
d. experience perceptual constancy.
18. The researcher David Hubel is best known for
a. mapping visual receptor cells.
b. discovering subjective contours.
c. identifying the neural pathways by which body sensations occur.
d. realizing that hearing and smell originate from the same brain
area.
19. The primary reason why psychologists study illusions is because
a. they help in identifying areas of the cortex that have been
damaged.
b. they serve as good “public relations” material for curious novices.
c. they help in categorizing people into good and bad perceivers.
d. they help in understanding how perception normally works.
20. The shrinking-square illusion demonstrated by Misha Pavel relies
on processing of which kinds of feature?
a. edges and corners
b. color and texture
c. torque and angular momentum
d. density gradients and motion

Learning and Human Nurture4
Psychology MattersCore ConceptsKey Questions/Chapter Outline
4.1 What Sort of Learning Does
Classical Conditioning Explain?
The Essentials of Classical Conditioning
Applications of Classical Conditioning
Classical conditioning is a basic form
of learning in which a stimulus that
produces an innate reflex becomes
associated with a previously neutral
stimulus, which then acquires the power
to elicit essentially the same response.
Taste Aversions and
Chemotherapy
Your friend risks developing a food
aversion when medicine makes her
feel sick.
4.2 How Do We Learn New Behaviors
by Operant Conditioning?
Skinner’s Radical Behaviorism
The Power of Reinforcement
The Problem of Punishment
A Checklist for Modifying Operant
Behavior
Operant and Classical Conditioning
Compared
In operant conditioning, the
consequences of behavior, such as
rewards and punishments, influence
the probability that the behavior will
occur again.
Using Psychology to Learn
Psychology
If the Premack Principle doesn’t
work for you, try using behavioral
principles to make studying itself more
reinforcing.
According to cognitive psychology,
some forms of learning must be
explained as changes in mental
processes rather than as changes
in behavior alone.
Fear of Flying Revisited
A combination of classical
conditioning, operant conditioning,
and cognitive techniques makes fear
manageable.
CHAPTER PROBLEM Assuming Sabra’s fear of flying was a response she had learned, could it
also be treated by learning? If so, how?
CRITICAL THINKING APPLIED Do Different People Have Different “Learning Styles”?
4.3 How Does Cognitive Psychology
Explain Learning?
Insight Learning: Köhler in the Canaries
with Chimps
Cognitive Maps: Tolman Finds Out What’s
on a Rat’s Mind
Observational Learning: Bandura’s
Challenge to Behaviorism
Brain Mechanisms and Learning
“Higher” Cognitive Learning

133
I N 1924, JOHN WATSON BOASTED, “GIVE ME A DOZEN HEALTHY INFANTS, well-formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select—doctor, lawyer, artist, merchant-chief, and, yes, even beggar-man and thief, regardless of his tal-
ents, penchants, tendencies, abilities, vocations, and race of his ancestors.” Decades later, the
assumption behind Watson’s lofty claim became the bedrock on which the community called
Walden Two was built: Nurture trumps nature. Or, to put it another way: Environment carries far
more weight than heredity in determining our behavior.
At Walden Two, residents can enter any sort of profession that interests them. In their
leisure time, they can do whatever they like: attend concerts, lie on the grass, read, or perhaps
drink coffee with friends. They have no crime, no drug problems, and no greedy politicians. In
exchange for this happy lifestyle, community members must earn four “labor credits” each day,
doing work needed by the community. (That’s about 4 hours’ work—fewer hours for unpleasant
tasks, such as cleaning sewers, but more for the easiest work, perhaps pruning the roses.) Fol-
lowing Watson’s vision, the founder of Walden Two, a psychologist named Frasier, believed peo-
ple could have happy, fulfilling lives in an environment psychologically engineered to reward
people for making socially beneficial choices. To reap these benefits, all a community must do
is change the way it deals out rewards.
Where was this community built? Only in the mind of behaviorist B. F. Skinner. You see,
Walden Two is a novel written by Skinner (1948) to promote his ideas on better living through
behavioral psychology. But so alluring was the picture he painted of this mythical miniature
society that many real-world communes sprang up, using Walden Two as the blueprint.

134 C H A P T E R 4 Learning and Human Nurture
None of the real communities based on Walden Two ran so smoothly as the one in Skinner’s
mind. Yet at least one such group, Twin Oaks, located in Virginia, thrives after more than
40 years—but not without substantial modifications to Skinner’s vision (Kincade, 1973). In
fact, you can visit this group electronically through its website at www.twinoaks.org/index.html
(Twin Oaks, 2007).
Nor was behaviorism’s fate exactly as Skinner had envisioned it. Although the behaviorist
perspective dominated psychology during much of the 20th century, its fortunes fell as cog-
nitive psychology grew in prominence. But what remains is behaviorism’s substantial legacy,
including impressive theories of behavioral learning and a valuable set of therapeutic tools for
treating learned disorders—such as fears and phobias. To illustrate what behaviorism has given
us, consider the problem that confronted Sabra.
A newly minted college graduate, Sabra landed a dream job at an advertising firm in
San Francisco. The work was interesting and challenging, and she enjoyed her new colleagues.
The only problem was that her supervisor had asked her to attend an upcoming conference in
Hawaii—and take an extra few days of vacation there at the company’s expense. Why was that
a problem? Sabra had a fear of flying.
PROBLEM: Assuming Sabra’s fear of flying was a response she had learned, could it also
be treated by learning? If so, how?
A common stereotype of psychological treatment involves “reliving” traumatic experi-
ences that supposedly caused fear or some other symptom. Behavioral learning therapy,
however, works differently. It focuses on the here and now instead of the past: The
therapist acts like a coach, teaching the client new responses to replace old problem
behaviors. So, as you consider how Sabra’s fear might be treated, you might think along
the following lines:
• What problematic behaviors would we expect to see in people like Sabra who are
afraid of flying?
• What behaviors could Sabra learn to replace her fearful behavior?
• How could these new behaviors be taught?
While the solution to Sabra’s problem involves learning, it’s not the sort of hit-the-
books learning that usually comes to mind for college students. Psychologists define
the concept of learning broadly, as a process through which experience produces a last-
ing change in behavior or mental processes. According to this definition, then, Sabra’s
“flight training” would be learning—just as taking golf lessons or reading this text is a
learning experience.
To avoid confusion, two parts of our definition need elaboration. First, we underscore
the idea that learning involves a lasting change. Suppose you go to your doctor’s office
and get a particularly painful injection, during which the sight of the needle becomes as-
sociated with pain. The result: The next time you need a shot, and every time thereafter,
you wince when you first see the needle. This persistent change in responding involves
learning. In contrast, a simple, reflexive reaction, such as jumping when you hear an un-
expected loud noise, does not qualify as learning because it produces no lasting change—
nothing more than a fleeting reaction, even though it does entail a change in behavior.
Second, learning affects behavior or mental processes. In the doctor’s office exam-
ple above, it is easy to see how learning affects behavior. But mental processes are more
difficult to observe. How could you tell, for example, whether a laboratory rat had
simply learned the behaviors required to negotiate a maze (turn right, then left, then
right . . .) or whether it was following some sort of mental image of the maze, much as
you would follow a road map? (And why should we care what, if anything, was on a
rat’s mind?) Let’s venture a little deeper into our definition of learning by considering
the controversy surrounding mental processes.
learning A lasting change in behavior or mental
processes that results from experience.

www.twinoaks.org/index.html

C H A P T E R 4 Learning and Human Nurture 135
Behavioral Learning versus Cognitive Learning The problem of observing mental
events, whether in rats or in people, underlies a long-running controversy between
behaviorists and cognitive psychologists that threads through this entire chapter. For
more than 100 years, behaviorists maintained that psychology could be a true sci-
ence only if it disregarded subjective mental processes and focused solely on observ-
able stimuli and responses. On the other side of the issue, cognitive psychologists
contend that the behavioral view is far too limiting and that understanding learning
requires us to make inferences about hidden mental processes. In the following pages,
we will see that both sides in this dispute have made important contributions to our
knowledge.
Learning versus Instincts So, what does learning—either behavioral or cognitive—
do for us? Nearly all human activity, from working to playing to interacting with fam-
ily and friends, involves some form of learning. Without learning, we would have no
human language. We wouldn’t know who our family or friends were. We would have
no memory of our past or goals for our future. And without learning, we would be
forced to rely on simple reflexes and a limited repertoire of innate behaviors, sometimes
known as “instincts.”
In contrast with learning, instinctive behavior is heavily influenced by genetic pro-
gramming, as we see in bird migrations or animal mating rituals. In humans, however,
behavior is much more influenced by learning than by instincts. For us, learning pro-
vides greater flexibility to adapt quickly to changing situations and new environments.
In this sense, then, learning represents an evolutionary advance over instincts.
Simple and Complex Forms of Learning Some forms of learning are quite simple.
For example, if you live near a busy street, you may learn to ignore the sound of the
traffic. This sort of learning, known as habituation, involves learning not to respond to
stimulation. Habituation occurs in all animals that have nervous systems, from insects
and worms to people. It helps you focus on important stimuli while ignoring stimuli
that need no attention, such as the feel of the chair you are sitting on or the sound of
the air conditioning in the background.
Another relatively simple form of learning is our general preference for familiar
stimuli as contrasted with novel stimuli. This mere exposure effxect occurs regardless
of whether the stimulus was associated with something pleasurable, or we were even
aware of the stimulus. The mere exposure effect probably accounts for the effective-
ness of much advertising (Zajonc, 1968, 2001). It also helps explain our attraction to
people we see often at work or school and for songs we have heard at least a few times.
Other kinds of learning can be more complex. One type involves learning a con-
nection between two stimuli—as when you associate a certain scent with a particular
person who wears that fragrance. Another occurs when we associate our actions with
rewarding or punishing consequences, such as a reprimand from the boss or an A
from a professor. The initial sections of the chapter will emphasize these two especially
important forms of behavioral learning, which we will call classical conditioning and
operant conditioning.
In the third section of the chapter, we shift our focus from external behavior to
internal mental processes. There, our look at cognitive learning will consider how
sudden “flashes of insight” and imitative behavior require theories that go beyond
behavioral learning to explain how we solve problems or why children imitate behav-
ior for which they see other people being rewarded. We will also discuss acquisition of
concepts, the most complex form of learning and, notably, the sort of learning you do
in your college classes. We will close the chapter on a practical note by considering how
to use the psychology of learning to help you study more effectively—and enjoy it.
Now, let’s begin—with a form of behavioral learning that accounts for many of
your own likes and dislikes: classical conditioning.
C O N N E C T I O N CHAPTER 9
Instinct refers to motivated
behaviors that have a strong
innate basis (p. 369).
habituation Learning not to respond to the
repeated presentation of a stimulus.
mere exposure effect A learned preference for
stimuli to which we have been previously exposed.
behavioral learning Forms of learning, such as
classical conditioning and operant conditioning, that
can be described in terms of stimuli and responses.
This giant leatherback turtle “instinc-
tively” returns to its birthplace each year
to nest. Although this behavior is heavily
influenced by genetics, environmental
cues such as tidal patterns play a role
as well. Thus, scientists usually shun
the term instinct, preferring the term
species-typical behavior.
The behavioral perspective says that
many abnormal behaviors are learned.

136 C H A P T E R 4 Learning and Human Nurture
4.1 KEY QUESTION
What Sort of Learning Does Classical Conditioning Explain?
Ivan Pavlov (1849–1936) would have been insulted had you called him a psychologist.
In fact, this Russian physiologist had only contempt for the structuralist and function-
alist psychology of his time, which he saw as hopelessly mired in speculation about
subjective mental life (Todes, 1997). Pavlov and the hundreds of student researchers
who passed through his research “factory” were famous for their work on the digestive
system—for which Pavlov eventually snared a Nobel prize (Fancher, 1979; Kimble,
1991).
Unexpectedly, however, their experiments on salivation (the first step in digestion)
went awry, sending Pavlov and his crew on a detour into the psychology of learning—
a detour that occupied Pavlov for the rest of his life. The problem they encountered
was that their experimental animals began salivating even before food was put in their
mouths (Dewsbury, 1997), which—from a biological perspective—was inexplicable, as
salivation normally occurs only after food enters the mouth. Yet, in Pavlov’s animals,
saliva would start flowing when they merely saw the food or they heard the footsteps
of the lab assistant bringing the food.
This response was a puzzle. What could be the biological function of salivating
before receiving food? When Pavlov and his associates turned their attention to under-
standing these “psychic secretions,” they made a series of discoveries that would for-
ever change the course of psychology (Pavlov, 1928; Todes, 1997). Quite by accident,
they had stumbled upon an objective model of learning that could be manipulated in
the laboratory to tease out the connections among stimuli and responses. This discov-
ery, now known as classical conditioning, forms the Core Concept of this section:
Core Concept 4.1
Classical conditioning is a basic form of learning in which a stimulus
that produces an innate reflex becomes associated with a previously
neutral stimulus, which then acquires the power to elicit essentially
the same response.
In the following pages, we will see that classical conditioning accounts for some
important behavior patterns found not only in animals but also in people. By means of
classical conditioning, organisms learn about cues that help them anticipate and avoid
danger, as well as cues alerting them to food, sexual opportunity, and other conditions
that promote survival. First, however, let’s examine the fundamental features Pavlov
identified in classical conditioning.
C O N N E C T I O N CHAPTER 1
Structuralism and functionalism
were two of the early “schools” of
psychology (p. 14).
classical conditioning A form of behavioral
learning in which a previously neutral stimulus
acquires the power to elicit the same innate reflex
produced by another stimulus.
To study classical conditioning, Pavlov (in
the center of the photo) placed his dogs
in a restraining apparatus. The dogs were
then presented with a neutral stimulus,
such as a tone. Through its association
with food, the neutral stimulus became a
conditioned stimulus eliciting salivation.

What Sort of Learning Does Classical Conditioning Explain? 137
The Essentials of Classical Conditioning
Pavlov’s work on learning focused on manipulating simple, automatic responses
known as reflexes (Windholz, 1997). Salivation and eye blinks are examples of such
reflexes, which commonly result from stimuli that have biological significance: The
blinking reflex, for example, protects the eyes; the salivation reflex aids digestion.
Pavlov’s great discovery was that his dogs could associate these reflexive responses
with new stimuli—neutral stimuli that had previously produced no response (such as
the sound of the lab assistant’s footsteps). Thus, they could learn the connection be-
tween a reflex and a new stimulus. For example, Pavlov found he could teach a dog to
salivate upon hearing a certain sound, such as the tone produced by striking a tuning
fork or a bell. You have experienced the same sort of learning if your mouth waters
when you read the menu in a restaurant.
To understand how these “conditioned reflexes” worked, Pavlov’s team employed
a simple experimental strategy. They first placed an untrained dog in a harness and set
up a vial to capture the animal’s saliva. Then, at intervals, they sounded a tone, after
which they gave the dog a bit of food. At first, the dog salivated only after receiving
the food—demonstrating a normal, biological reflex. But gradually, over a number of
trials pairing the tone with the food, the dog began to salivate in response to the tone
alone. Pavlov and his students had discovered that a neutral stimulus (one without any
reflex-provoking power, such as a tone or a light), when paired with a natural reflex-
producing stimulus (such as food), will by itself begin to elicit a learned response (sali-
vation) similar to the original reflex. In humans, classical conditioning is the learning
process that makes us associate romance with flowers or chocolate.
Figure 4.1 illustrates the main features of Pavlov’s classical conditioning proce-
dure. At first glance, the terms may seem a bit overwhelming. Nevertheless, you will
find it immensely helpful to study them carefully now so they will come to mind easily
later—when we analyze complicated, real-life learning situations, as in the acquisition
and treatment of fears, phobias, and food aversions.
Acquisition Classical conditioning always involves an unconditioned stimulus (UCS), a
stimulus that automatically—that is, without conditioning—provokes a reflexive re-
sponse. Pavlov used food as the UCS because it reliably produced the salivation reflex.
neutral stimulus Any stimulus that produces
no conditioned response prior to learning. When it is
brought into a conditioning experiment, the researcher
will call it a conditioned stimulus (CS). The assumption
is that some conditioning occurs after even one pairing
of the CS and UCS.
unconditioned stimulus (UCS) In classical
conditioning, UCS is the stimulus that elicits an
unconditioned response.
Unconditioned response (UCR)
Automatically
elicits
Before conditioning
During conditioning (acquisition)
Food
Unconditioned stimulus (UCS)
Neutral stimulus (NS)
Neutral stimulus (NS)
Tone
Unconditioned response (UCR)Unconditioned stimulus (UCS)
Conditioned response (CR)
No response or irrevelant response
Salivation
Salivation
Salivation
No salivation
Food
Followed by Elicits
Elicits
Tone
After conditioning
Conditioned stimulus (CS)
Tone
FIGURE 4.1
Basic Features of Classical
Conditioning
Before conditioning, the food (UCS) natu-
rally elicits salivation (UCR). A tone from
a tuning fork is a neutral stimulus (NS)
and has no effect. During conditioning
(the acquisition phase), the tone (NS)
is paired with the food (UCS), which
continues to elicit the salivation response
(UCR). Through its association with the
food, the previously neutral tone becomes
a conditioned stimulus (CS), gradually
producing a stronger and stronger
salivation response (CR).
Source: Zimbardo, P.G., & Gerrig, R. J.. (1999).
Psychology and Life, 15th ed. Boston, MA: Allyn and
Bacon. Copyright © 1999 by Pearson Education.
Reprinted by permission of the publisher.

138 C H A P T E R 4 Learning and Human Nurture
In the language of classical conditioning, then, this is called an unconditioned reflex
or, more commonly, an unconditioned response (UCR). It is important to realize that the
UCS–UCR connection is “wired in” and so involves no learning. His dogs didn’t have
to learn to salivate when they received food, just as you don’t have to learn to cry out
when you feel pain: Both are unconditioned responses.
Acquisition, the initial learning stage in classical conditioning, pairs a new stimulus—a
neutral stimulus (NS)—with the unconditioned stimulus. Typically, after several trials, the
neutral stimulus (the tone produced by a tuning fork, for example) will elicit essentially the
same response as does the UCS. So, in Pavlov’s experiments, when the sound alone began
to produce salivation, this formerly neutral stimulus became a conditioned stimulus (CS).
Although this response to the conditioned stimulus is essentially the same as the response
originally produced by the unconditioned stimulus, we now refer to it as the conditioned
response (CR)—because it is occurring as a result of conditioning, or learning. The same
thing may have happened to you in grade school, when your mouth watered (a condi-
tioned response) at the sound of the lunch bell (a conditioned stimulus).
In conditioning, as in telling a joke, timing is critical. In most cases, the CS and
UCS must occur contiguously (close together in time) so the organism can make the
appropriate connection during acquisition. The range of time intervals between the CS
and UCS that produces the best conditioning depends on the type of response being
conditioned. For motor responses, such as eye blinks, a short interval of one second or
less is best. For visceral responses, such as heart rate and salivation, longer intervals of
five to 15 seconds work best. Conditioned fear optimally requires even longer intervals
of many seconds or even minutes between the CS and the UCS. Taste aversions, we will
see, can develop even after several hours’ delay. (These time differentials probably have
survival value. For example, in the case of taste aversions, rats seem to be genetically
programmed to eat small amounts of an unfamiliar food and, if they don’t get sick,
return to the food after a few hours.)
These, then, are the building blocks of classical conditioning: the UCS, UCR, NS
(which becomes the CS), CR, and the timing that connects them. Why did it take Pavlov
three decades and 532 experiments to study such a simple phenomenon? There was
more to classical conditioning than first met Pavlov’s eyes. Along with acquisition, he
also discovered extinction, spontaneous recovery, generalization, and discrimination—
which we will now explore.
Extinction and Spontaneous Recovery As a result of your grade-school experience
with lunch bells, would your mouth still water at the sound of a school bell in your
neighborhood today? In other words, do conditioned responses remain permanently in
your behavioral repertoire? The good news, based on experiments by Pavlov’s group,
suggests they do not. Conditioned salivation responses in Pavlov’s dogs were easily
eliminated by withholding the UCS (food) over several trials in which the CS (the tone)
was presented alone. In the language of classical conditioning, we call this extinction (in
classical conditioning). It occurs when a conditioned response disappears after repeated
presentations of the CS without the UCS. Figure 4.2 shows how the conditioned re-
sponse (salivation) becomes weaker and weaker during extinction trials. So, after years
of hearing bells that were not immediately followed by food, we would not expect your
mouth-watering response upon hearing a bell today. Extinction, then, is of considerable
importance in behavioral therapies for fears and phobias, such as Sabra’s fear of flying.
Now for the bad news: Imagine that, after many years, you are visiting your old
grade school to give a presentation to the first graders. While you are there, the lunch
bell rings—and, to your surprise, your mouth waters. Why? The conditioned response
has made a spontaneous recovery. Much the same thing happened with Pavlov’s dogs:
Some time after undergoing extinction training, they would salivate again when they
heard the tone. In technical terms, this spontaneous recovery occurs when the CR reap-
pears after extinction and after a period without exposure to the CS. Happily, when
spontaneous recovery happens, the conditioned response nearly always reappears at a
lower intensity, as you can see in Figure 4.2. In practice, then, the CR can gradually be
eliminated, although this may require several extinction sessions.
unconditioned response (UCR) In classical
conditioning, the response elicited by an unconditioned
stimulus without prior learning.
acquisition The initial learning stage in classical
conditioning, during which the conditioned response
comes to be elicited by the conditioned stimulus.
conditioned stimulus (CS) In classical
conditioning, a previously neutral stimulus that comes
to elicit the conditioned response. Customarily, in a
conditioning experiment, the neutral stimulus is called
a conditioned stimulus when it is first paired with an
unconditioned stimulus (UCS).
conditioned response (CR) In classical
conditioning, a response elicited by a previously
neutral stimulus that has become associated with
the unconditioned stimulus.
extinction (in classical conditioning) The
weakening of a conditioned response in the absence
of an unconditioned stimulus.
C O N N E C T I O N CHAPTER 13
Behavioral therapies are based
on classical conditioning and
operant conditioning (p. 568).
spontaneous recovery The unexpected
reappearance of an extinguished conditioned response
after a time delay.

What Sort of Learning Does Classical Conditioning Explain? 139
Generalization Now, switching to a visual CS, suppose you have developed a fear of
spiders. Most likely, you will probably respond the same way to spiders of all sizes and
markings. We call this stimulus generalization: giving a conditioned response to stimuli
that are similar to the CS. Pavlov demonstrated stimulus generalization in his labo-
ratory by showing that a well-trained dog would salivate in response to a tone of a
slightly different pitch from the one used during conditioning. As you would expect,
the closer the new sound was to the original, the stronger the response.
In everyday life, we see stimulus generalization when people acquire fears as a
result of traumatic events. So a person who was bitten by a dog may develop a fear of
all dogs rather than fearing only the specific dog responsible for the attack. Likewise,
stimulus generalization accounts for an allergy sufferer’s sneeze upon seeing a paper
flower. In short, by means of stimulus generalization, we learn to give old responses in
new situations.
Discrimination Learning As a child, you may have learned to salivate at the sound
of the lunch bell, but—thanks to stimulus discrimination—your mouth probably didn’t
water when the doorbell rang. Much the opposite of stimulus generalization, stimulus
discrimination occurs when an organism learns to respond to one stimulus but not to
stimuli that are similar. Pavlov and his students demonstrated this when they taught
dogs to distinguish between two tones of different frequencies. Once again, their pro-
cedure was simple: One tone was followed by food while another was not. Over a
series of trials, the dogs gradually learned to discriminate between the tones, evidenced
in salivation elicited by one tone and not the other. Beyond the laboratory, stimulus
discrimination is the concept that underlies advertising campaigns aimed at condition-
ing us to discriminate between particular brands, as in the perennial battle between
Pepsi and Coke.
Applications of Classical Conditioning
The beauty of classical conditioning is that it offers a simple explanation for many
behaviors, from cravings to aversions. Moreover, it gives us the tools for eliminating
unwanted human behaviors—although Pavlov himself never attempted any therapeu-
tic applications. Instead, it fell to the American behaviorist, John Watson, to apply
classical conditioning techniques to human problems.
The Notorious Case of Little Albert More than 90 years ago, John Watson and
Rosalie Rayner first demonstrated conditioned fear in a human (Brewer, 1991;
Fancher, 1979). In an experiment that would be considered unethical today, Watson
and Rayner (1920/2000) conditioned an infant named Albert to react fearfully to
stimulus generalization The extension of a
learned response to stimuli that are similar to the
conditioned stimulus.
stimulus discrimination Learning to respond
to a particular stimulus but not to stimuli that are
similar.
Trials
St
re
n
g
th
o
f
th
e
C
R
(W
ea
k)
(S
tr
o
n
g
) (1)
Acquisition
(NS + UCS)
(2)
Extinction
(CS alone)
(3)
Spontaneous
recovery and
re-extinction
(CS alone)
N
o
e
xp
o
su
re
t
o
C
S
(Time )
FIGURE 4.2
Acquisition, Extinction, and
Spontaneous Recovery
(1) During acquisition (NS + UCS), the
strength of the CR increases rapidly,
after which the NS becomes the CS.
(2) During extinction, when the UCS no
longer follows the CS, the strength of the
CR drops to zero. (3) After extinction, the
CR may occasionally reappear, even when
the UCS is still not presented; only the
CS alone occurs. This reappearance of
the CR is called “spontaneous recovery.”
Source: Zimbardo, P.G., & Gerrig, R. J. (1999).
Psychology and Life, 15th ed. Boston, MA: Allyn and
Bacon. Copyright © 1999 by Pearson Education.
Reprinted by permission of the publisher.
Stimulus
Generalization and Stimulus Discrimination
Explore the Concept
at MyPsychLab

140 C H A P T E R 4 Learning and Human Nurture
a white laboratory rat. They created the fear response by repeatedly presenting the
rat, paired with the loud sound of a steel bar struck with a mallet, which acted as an
aversive UCS. It took only seven trials for “Little Albert” to react with distress at the
appearance of the rat (CS) alone. After Albert’s response to the rat had become well
established, Watson and Rayner showed that his aversion readily generalized from the
rat to other furry objects, such as a Santa Claus mask and a fur coat worn by Watson
(Harris, 1979).
Most likely, the experiment caused Albert only temporary distress, because his
fear response extinguished rapidly, making it necessary for Watson and Raynor to
renew the fear conditioning periodically. In fact, the need to recondition Albert
nearly ended the whole experiment when Watson and Rayner were attempting to
generalize the child’s fear to a dog, a rabbit, and a sealskin coat. Watson decided to
“freshen the reaction to the rat” by again striking the steel bar. The noise startled the
dog, which began to bark, frightening not only Little Albert but both experimenters
(Harris, 1979).
Unlike Little Albert’s short-lived aversion to furry objects, some fears learned under
highly stressful conditions can persist for years (LeDoux, 1996). During World War
II, the Navy used a gong sounding at the rate of 100 rings a minute as a call to battle
stations. For combat personnel aboard ship, this sound became strongly associated
with danger—a CS for emotional arousal. The persistent effect of this association was
shown in a study conducted 15 years after the war, when Navy combat veterans still
gave a strong autonomic reaction to the old “call to battle stations” (Edwards & Acker,
1962).
Like those veterans, any of us can retain a readiness to respond to old emotional
cues. Fortunately, however, classical conditioning also provides tools for eliminating
troublesome conditioned fears (Wolpe & Plaud, 1997). One strategy combines extinc-
tion of the conditioned fear response with counterconditioning, a therapy that teaches
a relaxation response to the CS. This approach has been particularly effective in deal-
ing with phobias. As you may be thinking, we ought to consider counterconditioning
as part of the treatment plan to help Sabra conquer her fear of flying.
Conditioned Food Aversions All three of your authors have had bad experiences
with specific foods. Phil got sick after eating pork and beans in the grade school lunch-
room, Bob became ill after a childhood overdose of olives, and Vivian became queasy
after eating chicken salad (formerly one of her favorite meals). In all three cases, we
associated our distress with the distinctive sight, smell, and taste of the food—which,
for years afterward, was enough to cause feelings of nausea.
Unpleasant as it is, learning to avoid a food associated with illness has survival
value. That’s why humans and other animals readily form an association between ill-
ness and food—much more readily than between illness and a nonfood stimulus, such
as a light or a tone. For example, nothing else present in your authors’ environments
during their bad food experiences became associated with nausea. Phil didn’t become
wary of the trays his school lunches were served on, Bob didn’t develop a reaction to
the highchair in which he developed his olive antipathy, and Vivian didn’t avoid the
friends who were dining with her when she ate the treacherous meal. It was solely the
foods that became effective conditioned stimuli.
John Garcia and Robert Koelling (1966) first recognized this highly selective
CS–UCS connection when they noticed rats wouldn’t drink from water bottles in the
chambers where they had previously been made nauseous by radiation. Could the rats
be associating the taste of the water in those bottles with being sick? Subsequent ex-
periments confirmed their suspicions and led to yet another important discovery. Rats
readily learned an association between flavored water and illness, yet the rats could
not be conditioned to associate flavored water with the pain of an electric shock de-
livered through a grid on the floor of the test chamber. This makes good sense from
an evolutionary perspective, because illness can easily result from drinking (or eat-
ing) poisonous substances but rarely occurs following a sharp pain to the feet. Simi-
larly, rats easily learned to fear bright lights and noise when they preceded an electric
C O N N E C T I O N CHAPTER 2
The autonomic nervous system
regulates the internal organs
(p. 57).
John Watson and Rosalie Rayner
conditioned Little Albert to fear
furry objects like this Santa Claus
mask (Discovering Psychology,
1990). For years, no one knew
what had become of Little Albert
after the research. Archival records
recently revealed that, sadly,
Douglass Merritte—the boy known
as Little Albert—died just a few
years later from acquired hydro-
cephalus (Beck, et al., 2009).

What Sort of Learning Does Classical Conditioning Explain? 141
shock—but could not learn to connect those light and sound cues with subsequent
illness. Such observations suggest that organisms have an inborn preparedness to
associate certain stimuli with certain consequences, while other CS–UCS combinations
are highly resistant to learning.
Biological Predispositions: A Challenge to Pavlov A major insight resulting from
the Garcia and Koelling experiments is that conditioned aversions involve both nature
and nurture. That is, the tendency to develop taste aversions appears to be “wired in”
as part of our biological nature rather than purely learned. It is this biological basis for
taste aversions that prompts psychologists to question some aspects of Pavlov’s origi-
nal theory of classical conditioning (Rescorla & Wagner, 1972).
Biological predispositions may also impact the timing involved in acquiring a
conditioned aversion. For example, food aversions can develop even when the time
interval between eating and illness extends over several hours—as compared with
just a few seconds in Pavlov’s experiments. Again, this suggests that in food aversions,
we are not dealing with a simple classically conditioned response as Pavlov under-
stood it but, instead, with a response based as much in nature (biology) as in nurture
(learning).
And such biological predispositions go far beyond taste and food aversions.
Psychologists now believe that many common fears and phobias arise from genetic
preparedness, built into us from our ancestral past, disposing us to learn fears of harm-
ful objects: snakes, spiders, blood, lightning, heights, and closed spaces. Likewise, anxi-
ety about mutilation or other bodily harm can contribute to fears of seemingly modern
objects or situations, such as injections, dentistry, or flying.
Real-World Applications of Classical Conditioning Examples of the impact of
classical conditioning on human and on animal behavior abound. One clever experi-
ment by John Garcia and his colleagues demonstrated how aversive conditioning can
dissuade wild coyotes from attacking sheep. They did so by wrapping toxic lamb burg-
ers in sheepskins and stashing them on sheep ranches: When roaming coyotes found
and ate these meaty morsels, they became sick and—as predicted—developed a dis-
taste for lamb meat. The result was a whopping 30 to 50 percent reduction in sheep
attacks! So powerful was this aversion that, when captured and placed in a cage with a
sheep, the coyotes would not get close to it. Some even vomited at the sight of a sheep
(Garcia, 1990). Unfortunately, this type of conditioning does not appear to extend to
sheep ranchers’ behavior: Despite the success of these experiments in natural predator
control, scientists have been unable to get the ranchers to use this method. Apparently,
sheep ranchers have a strong aversion to feeding lamb to coyotes!
Need help getting to sleep, studying, or getting yourself to the gym? A little clas-
sical conditioning might help: Try finding positive stimuli to associate with each of
those activities. For example, experts recommend keeping your sleeping area quiet
and peaceful at all times of the day and night so you learn to associate it with relax-
ation. Similarly, creating for yourself a specific study space that offers a comfortable
chair, pleasant aromas or tastes, or other sensations that positively stimulate you
will help you associate those positive stimuli with studying—especially if you allow
yourself exposure to these particular stimuli only when you study. And the same
principles apply to your efforts to exercise more: If you listen to your favorite music
only while working out, chances are you’ll start getting that pumped-up, “feels good
to exercise” feeling when you hear it—and then you can use it as a stimulus to get
yourself to the gym!
What is the big lesson coming out of all this work on classical conditioning? Con-
ditioning involves both nature and nurture. That is, conditioning depends not only on
the learned relationship among stimuli and responses but also on the way an organ-
ism is genetically attuned to certain stimuli in its environment (Barker et al., 1978;
Dickinson, 2001). What any organism can—and cannot—learn in a given setting is
to some extent a product of its evolutionary history (Garcia, 1993). And that is a
concept that Pavlov never understood.
A conditioned taste aversion can make
a coyote stop killing sheep.

142 C H A P T E R 4 Learning and Human Nurture
4.2 KEY QUESTION
How Do We Learn New Behaviors By Operant Conditioning?
With classical conditioning, you can teach a dog to salivate, but you can’t teach it to
sit up or roll over. Why? Salivation is a passive, involuntary reflex, while sitting up
and rolling over are much more complex responses that we usually think of as vol-
untary. To a behavioral psychologist, however, such “voluntary” behaviors are really
controlled by rewards and punishments. And because rewards and punishments play
PSYCHOLOGY MATTERS
Taste Aversions and Chemotherapy
Imagine that your friend Jena is about to undergo her first round of chemotherapy, just
to make sure any stray cells from the tumor found in her breast will be destroyed. To her
surprise, the nurse enters the lab, not with the expected syringe, but with a dish of licorice-
flavored ice cream. “Is this a new kind of therapy?” she asks. The nurse replies that it
is, indeed, explaining that most patients who undergo chemotherapy experience nausea,
which can make them “go off their feed” and quit eating, just when their body needs
nourishment to fight the disease. “But,” says the nurse, “We have found a way around the
problem. If we give patients an unusual food before their chemotherapy, they usually de-
velop an aversion only to that food.” She continues, “Did you ever hear of Pavlov’s dogs?”
Conditioned food aversions make evolutionary sense, as we have seen, because
they helped our ancestors avoid poisonous foods. As is the case with some of our other
evolutionary baggage, such ancient aversions can cause modern problems. People un-
dergoing chemotherapy often develop aversions to normal foods in their diets to such
an extent that they become malnourished. The aversions are nothing more than con-
ditioned responses in which food (the CS) becomes associated with nausea. Chemo-
therapy personnel trained in classical conditioning use their knowledge to prevent the
development of aversions to nutritive foods by arranging for meals to be withheld just
before chemotherapy. And, as in Jena’s case, they also present a “scapegoat” stimulus.
By consuming candies or ice cream with unusual flavors before treatment, patients
develop taste aversions only to those special flavors. For some patients, this practical
solution to problems with chemotherapy may make the difference between life and
death (Bernstein, 1988, 1991).
4. UNDERSTANDING THE CORE CONCEPT: Which one of the
following could be an unconditioned stimulus (UCS) involved in
classical conditioning?
a. food
b. a flashing light
c. music
d. money
Check Your Understanding
1. APPLICATION: Give an example of classical conditioning from
your everyday life and identify the UCS, UCR, NS (which becomes
the CS), and CR.
2. RECALL: Before a response, such as salivation, becomes a
conditioned response, it is a(n) .
3. APPLICATION: If you learned to fear electrical outlets after
getting a painful shock, what would be the CS?
Answers 1. Everyday examples of classical conditioning involve learning taste aversions (such as a dislike for olives) or fears (such as a fear of going to
the dentist), as well as responses developed through association with positive stimuli. For example, if you develop feelings of contentment from the
smell of your grandmother’s house, the UCS is your grandmother’s house, the UCR the contentment you feel when you are with her, the NS the smell
of her house, which becomes the CS when you learn to associate it with her (after visiting her at her house several times). 2. innate reflex or UCR 3.
The electrical outlet 4. a—because it is the only one that produces an innate reflexive response (UCR).
Study and Review at MyPsychLab

How Do We Learn New Behaviors By Operant Conditioning? 143
no role in classical conditioning, another important form of learning must be at work.
Psychologists call it operant conditioning. (An operant, incidentally, is an observable
behavior that an organism uses to “operate” in, or have an effect on, the environment.
Thus, if you are reading this book to get a good grade on the next test, reading is
an operant behavior.) You might also think of operant conditioning as a form of learning
in which the consequences of behavior can encourage behavior change. The Core Concept
of this section puts the idea this way:
Core Concept 4.2
In operant conditioning, the consequences of behavior, such as
rewards and punishments, influence the probability that the behavior
will occur again.
Common rewarding consequences include money, praise, food, or high grades—all
of which can encourage the behavior they follow. By contrast, punishments such as
pain, loss of privileges, or low grades can discourage the behavior they follow.
As you will see, the theory of operant conditioning is an important one for at
least two reasons. First, operant conditioning accounts for a much wider spectrum of
behavior than does classical conditioning. And second, it explains new and voluntary
behaviors—not just reflexive behaviors.
Skinner’s Radical Behaviorism
The founding father of operant conditioning, American psychologist
B. F. Skinner (1904–1990), based his whole career on the idea that
the most powerful influences on behavior are its consequences: what
happens immediately after the behavior. Actually, it wasn’t Skinner’s
idea originally. He borrowed the notion of behavior being controlled
by rewards and punishments from another American psychologist,
Edward Thorndike, who demonstrated how hungry animals would
work diligently to solve a problem by trial and error to obtain a food
reward. Gradually, on succeeding trials, erroneous responses were
eliminated and effective responses were “stamped in.” Thorndike
called this the law of effect (see Figure 4.3). The idea was that an ani-
mal’s behavior leads to pleasant or unpleasant results that influence
whether the animal will try those behaviors again.
The first thing Skinner did with Thorndike’s psychology, however,
was to rid it of subjective and unscientific speculation about the or-
ganism’s feelings, intentions, or goals. What an animal “wanted” or
the “pleasure” it felt was not important for an objective understand-
ing of the animal’s behavior. As a radical behaviorist, Skinner refused
to consider what happens in an organism’s mind, because such specu-
lation cannot be verified by observation—and studying anything not
directly observable threatened the scientific credibility of the fledgling
field of psychology. For example, eating can be observed, but we can-
not observe the inner experiences of hunger, the desire for food, or
pleasure at eating.
The Power of Reinforcement
Skinner’s passionate commitment to the establishment of behaviorism
as a legitimate science permeated his work. For example, while we
often speak of “reward” in casual conversation, Skinner preferred the
more objective term reinforcer. Why so concerned over terminology?
Skinner objected to the term reward on the grounds that rewards
operant conditioning A form of behavioral
learning in which the probability of a response is
changed by its consequences—that is, by the stimuli
that follow the response.
reinforcer A condition (involving either the
presentation or removal of a stimulus) that occurs
after a response and strengthens that response.
law of effect The idea that responses that pro-
duced desirable results would be learned or “stamped”
into the organism.
FIGURE 4.3
A Thorndike Puzzle Box
Unlike Pavlov’s dogs, Thorndike’s cats faced a problem requir-
ing some kind of voluntary action on their part: how to open the
door in the puzzle box to get a food reward lying just outside.
To solve this problem, the animals used trial-and-error learning,
rather than simple reflexive responses. At first, their responses
seemed random, but gradually they eliminated ineffective be-
haviors. And when the effects of their behavior were desirable
(that is, when the door finally opened and the animals got the
food), they used this strategy on subsequent trials. This change
in behavior based on consequences of previous trials is called
the law of effect. Much the same trial-and-error learning occurs
when you learn a skill, such as shooting a basketball.

144 C H A P T E R 4 Learning and Human Nurture
imply pleasure on the part of the recipient, which in turn assumes knowledge of the
organism’s inner experience—which was forbidden territory. Reinforcers, on the other
hand, act on the behavior (rather than the organism’s mind), which is directly observ-
able (Winn, 2001). So Skinner defined a reinforcer as any stimulus that follows and
strengthens a response. Food, money, and sex serve this function for most peoples; so
do attention, praise, or a smile. All these are examples of positive reinforcement, which
strengthens a response by occurring after the response and making the behavior more
likely to occur again.
Most people know about positive reinforcement, of course, but fewer people under-
stand the other main way to strengthen operant responses: the reinforcement of behav-
ior by the removal of an unpleasant or aversive stimulus. Psychologists call this negative
reinforcement. (The word negative here is used in the mathematical sense of subtract or
remove, while positive means add or apply. Please be careful not to make the common
mistake of confusing negative reinforcement with punishment: Instead, remember that
reinforcement always strengthens behavior, whereas punishment—which we’ll discuss
shortly—weakens it.) So using an umbrella to avoid getting wet during a downpour
is a behavior learned and maintained by negative reinforcement. That is, you use the
umbrella to avoid or remove an unpleasant stimulus (getting wet). Likewise, when you
buckle your seat belt to stop the annoying sound of the seat-belt buzzer in your car, you
are receiving negative reinforcement. And taking a few minutes right now to highlight
the distinction between negative reinforcement and punishment in your notes will help
you avoid the unpleasant consequence of missing that question on the exam—providing
yet another example of the power of negative reinforcement to strengthen behavior!
Reinforcing Technology: The “Skinner Box” One of B. F. Skinner’s (1956) innova-
tions was a simple device for studying the effects of reinforcers on laboratory animals:
a box with a lever an animal could press to obtain food. He called this device an
operant chamber. (Nearly everyone else called it a “Skinner box,” a term he detested.)
Over the years, thousands of psychologists have used the apparatus to study operant
conditioning.
The virtue of the operant chamber lay in its capacity to control the timing and
frequency of reinforcement, factors that exert important influences on behavior, as you
will soon see. Moreover, the Skinner box could be programmed to conduct experi-
ments at any time of day—even when the researcher was home in bed.
Contingencies of Reinforcement The timing and frequency of reinforcement deter-
mines its effect on behavior. So while grade reports delivered two or three times a year
may reinforce college and university students for their studying, such a schedule has
little effect on their day-to-day study habits. Many professors realize this, of course,
positive reinforcement A stimulus presented
after a response and increasing the probability of that
response happening again.
negative reinforcement The removal of an
unpleasant or aversive stimulus, contingent on a
particular behavior. Contrast with punishment.
operant chamber A boxlike apparatus that
can be programmed to deliver reinforcers and
punishers contingent on an animal’s behavior. The
operant chamber is often called a “Skinner box.”
In this cartoon, the child was positively reinforced for crying by being allowed to sleep with mom and dad. Ironically, this is
negative reinforcement for the parents, as they are letting the child sleep in their bed in order to avoid being disturbed by a
crying baby.
Source: Hi & Lois © King Features Syndicate.

How Do We Learn New Behaviors By Operant Conditioning? 145
and schedule exams and assignments to award grades periodically throughout their
courses. In this way, they encourage continual studying rather than one big push at the
end of the semester. But that’s not always enough.
Whether we’re talking about college students, Fortune 500 CEOs, or laboratory
rats, any plan to influence operant learning requires careful consideration of the tim-
ing and frequency of rewards. How often will they receive reinforcement? How much
work must they do to earn a reinforcer? Will they be reinforced for every response or
only after a certain number of responses? We will consider these questions below in
our discussion of reinforcement contingencies, involving the many possible ways of as-
sociating responses and reinforcers. And stay alert for the Psychology Matters at the
end of this section, where we will give you some tips for applying these principles to
your own studying.
Continuous versus Intermittent Reinforcement Suppose you want to teach your
dog a trick—say, sitting on command. It would be a good idea to begin the training
program with a reward for every correct response. Psychologists call this continuous
reinforcement. It’s a useful tactic early in the learning process, because rewarding ev-
ery correct response and ignoring the incorrect ones provide quick and clear feedback
about which responses are desired. In addition, continuous reinforcement is useful for
shaping complex new behaviors. Shaping, often used in animal training, involves the
deliberate use of rewards (and sometimes punishments) to encourage better and better
approximations of the desired behavior. (You have experienced shaping in school, as
a teacher taught you to read, write, or play a musical instrument by gradually setting
reinforcement contingencies Relationships
between a response and the changes in stimulation
that follow the response.
continuous reinforcement A type of rein-
forcement schedule by which all correct responses are
reinforced.
shaping An operant learning technique in which a
new behavior is produced by reinforcing responses that
are similar to the desired response.
B. F. Skinner is shown reinforcing the
animal’s behavior in an operant chamber
or “Skinner box.” The apparatus allows the
experimenter to control all the stimuli in the
animal’s environment.
Just to set the record straight, we’d like to mention a bit of trivia about the “baby tender” crib that
Skinner devised for his daughter, Deborah (Benjamin & Nielsen-Gammon, 1999). It consisted of an
enclosed, temperature-controlled box that unfortunately bore a superficial resemblance to the oper-
ant chambers used in his experiments. The public learned about the “baby tender” from an article
by Skinner in the magazine Ladies’ Home Journal. The story took on a life of its own, and, years
later, stories arose about Deborah Skinner’s supposed psychotic breakdown, lawsuits against
her father, and eventual suicide—none of which were true. In fact, Deborah grew up to be a
well-adjusted individual who loved her parents.

146 C H A P T E R 4 Learning and Human Nurture
higher standards.) By means of shaping, the teacher can continually
“raise the bar” or increase the performance level required for earn-
ing a reward. This tells the learner when performance has improved.
In general, then, we can say that continuous reinforcement is a good
strategy for shaping new behaviors.
Continuous reinforcement does have some drawbacks. For one
thing, failure to reward a correct response on one trial could easily
be misinterpreted as a signal that the response was not correct. Con-
sistency, then, is key to its success. Another drawback of continuous
reinforcement occurs after the reinforcer has been earned many times:
once the learner becomes satiated, the reinforcer loses its power to
motivate. For example, if someone were training you to shoot free
throws by rewarding you with a big candy bar after each successful
attempt, the first candy bar might be highly rewarding, but after you
have had several, the reward value dissipates.
Happily, once the desired behavior becomes well established (for
example, when your dog has learned to sit), the demands of the situ-
ation change. The learner no longer needs rewards to discriminate a correct response
from an incorrect one. It’s time to shift to intermittent reinforcement (also called partial
reinforcement), the rewarding of some, but not all, correct responses. A less frequent
schedule of reinforcement—perhaps, after every third correct response—still serves as
an incentive for your dog to sit on command, while helping to avoid satiation. In gen-
eral, whether we’re dealing with people or animals, intermittent reinforcement is the
most efficient way to maintain behaviors that have already been learned (Robbins,
1971; Terry, 2000). As a practical matter, the transition to intermittent reinforcement
can be made easier by mixing in social reinforcement (“Good dog!”) with more tan-
gible rewards (food, for example).
A big advantage of intermittent reinforcement is its resistance to extinction. The
operant version of extinction (in operant conditioning) occurs when reinforcement is with-
held, as when a gambler stops playing a slot machine that never pays off. Why do
responses strengthened by intermittent reinforcement resist extinction better than do
continuously rewarded responses? Imagine two gamblers and two slot machines. One
machine inexplicably pays off on every trial, and another, more typical, machine pays
on an unpredictable, intermittent schedule. Now, suppose both devices suddenly stop
paying. Which gambler will catch on first? The one who has been rewarded for each
push of the button (continuous reinforcement) will quickly notice the change, while
the gambler who has won only occasionally (on partial reinforcement) may continue
playing unrewarded for a long while.
Schedules of Reinforcement Now that we have convinced you of the power of
intermittent reinforcement, you should know it occurs in two main forms or schedules
of reinforcement. One, the ratio schedule, rewards after a certain number of responses.
The other, known as an interval schedule, reinforces after a certain time interval. Let’s
look at the advantages and disadvantages of each. As you read this section, refer fre-
quently to Figure 4.4, which provides a visual summary of the results of each type of
reinforcement.
Ratio Schedules Suppose you own a business and pay your employees based on the
amount of work they perform: You are maintaining them on a ratio schedule of rein-
forcement. That is, ratio schedules occur when rewards depend on the number of cor-
rect responses (see Figure 4.4). Psychologists make a further distinction between two
subtypes of ratio schedules, fixed ratio and variable ratio schedules.
Fixed ratio (FR) schedules commonly occur in industry, when workers are paid on
a piecework basis—a certain amount of pay for a certain amount of production. So
if you own a tire factory and pay each worker a dollar for every five tires produced,
you are using a fixed ratio schedule. Under this scheme, the amount of work (the num-
ber of responses) needed for a reward remains constant, but the faster people work,
the more money they get. Not surprisingly, management likes FR schedules because
intermittent reinforcement A type of
reinforcement schedule by which some, but not all,
correct responses are reinforced; also called partial
reinforcement.
extinction (in operant conditioning) A
process by which a response that has been learned is
weakened by the absence or removal of reinforcement.
(Compare with extinction in classical conditioning.)
schedule of reinforcement A program speci-
fying the frequency and timing of reinforcements.
ratio schedule A program by which reinforce-
ment depends on the number of correct responses.
interval schedule A program by which reinforce-
ment depends on the time interval elapsed since the
last reinforcement.
fixed ratio (FR) schedule A program by which
reinforcement is contingent on a certain, unvarying
number of responses.
Shaping was undoubtedly used to get the
dolphins to jump this high: They were
likely reinforced gradually for higher and
higher jumps until they eventually only
received reinforcement for the highest
jump.

How Do We Learn New Behaviors By Operant Conditioning? 147
the rate of responding is usually high (Terry, 2000; Whyte, 1972), or, in other words,
it keeps people working quickly. Retail establishments also use fixed ratio schedules
when, for example, you receive a free pizza after buying ten pizzas from your local
pizza shop—which keeps you coming back to the same place for your next pizza.
Variable ratio (VR) schedules are less predictable. Telemarketers work on a VR sched-
ule, because they never know how many calls they must make before they get the next
sale, which acts as a reinforcer for the caller. Slot machine players also respond on a
variable ratio schedule, never knowing when the machine will pay off. In both cases,
continually changing the requirements for reinforcement keeps responses coming at
a high rate—so high, in fact, that the VR schedule usually produces more responding
than any other reinforcement schedule. In a demonstration of just how powerful a VR
schedule could be, Skinner showed that a hungry pigeon would peck a disk 12,000
times an hour for rewards given, on the average, for every 110 pecks (Skinner, 1953)!
Interval Schedules Time is of the essence on an interval schedule. That is, with
an interval schedule, reinforcement depends on responses made within a certain
time period (rather than on the total number of responses given) (see Figure 4.4).
Psychologists distinguish the same two kinds of interval schedules as ratio schedules:
fixed interval and variable interval schedules.
Fixed interval (FI) schedules commonly occur in the work world, where they may
appear as a periodic paycheck or praise from the boss at a monthly staff meeting. A
student who studies for a weekly quiz is also on a fixed interval schedule. In all such cases,
the interval does not vary, so the time period between rewards remains constant. You may
have already guessed that fixed interval reinforcement usually results in a comparatively
low response rate. Ironically, this is the schedule most widely adopted by business. Even a
rat in a Skinner box programmed for a fixed interval schedule soon learns it must produce
only a limited amount of work during the interval to get its reward. Pressing the lever
more often than required to get the food reward is just wasted energy. Thus, both rats and
humans on fixed interval schedules may display only modest productivity until near the
end of the interval, when the response rate increases rapidly. (Think of college students
facing a term paper deadline.) Graphically, in Figure 4.4, you can see the “scalloped” pat-
tern of behavior that results from this flurry of activity near the end of each interval.
Variable interval (VI) schedules are, perhaps, the most unpredictable of all. On a VI sched-
ule, the time interval between rewards (or punishments) varies. The resulting rate of re-
sponding can be high, although not usually as high as for the VR schedule. (Think about
it this way: You control the frequency of reward on the ratio schedule, because the faster
you work, the sooner you reach the magic number required for the reward. On interval
schedules, though, no matter how slowly or quickly you work, you cannot make time
pass any faster: Until the specified amount of time has passed, you will not receive your
reward.) For a pigeon or a rat in a Skinner box, the variable interval schedule may be a
30-second interval now, three minutes next, and a one-minute wait later. In the classroom,
pop quizzes exemplify a VI schedule, as do random visits by the boss or drug tests on the
job. And watch for responses typical of a VI schedule while waiting for an elevator: Be-
cause the delay between pressing the call button and the arrival of the elevator varies each
time, some of your companions will press the button multiple times—much like pigeons in
a Skinner box—as if more responses within an unpredictable time interval could control
the elevator’s arrival.
Primary and Secondary Reinforcers You can easily see why stimuli that fulfill basic
biological needs or desires provide reinforcement: Food reinforces a hungry animal, and
water reinforces a thirsty one. Similarly, the opportunity for sex becomes a reinforcer
for a sexually aroused organism. Psychologists call such stimuli primary reinforcers.
But money or grades provide a different sort of reinforcement: You can’t eat them
or drink them. Nor do they directly satisfy any physical need. So why do such things
reinforce behavior so powerfully? Neutral stimuli, such as money or grades, acquire a
reinforcing effect by association with primary reinforcers and so become conditioned
reinforcers or secondary reinforcers for operant responses. The same thing happens with
praise, smiles of approval, gold stars, “reward cards” used by merchants, and various
variable ratio (VR) schedule A reinforcement
program by which the number of responses required for
a reinforcement varies from trial to trial.
fixed interval (FI) schedule A program by
which reinforcement is contingent upon a certain, fixed
time period.
variable interval (VI) schedule A program
by which the time period between reinforcements varies
from trial to trial.
primary reinforcer A reinforcer, such as food or
sex, that has an innate basis because of its biological
value to an organism.
conditioned reinforcer or secondary
reinforcer A stimulus, such as money or tokens,
that acquires its reinforcing power by a learned
association with primary reinforcers.
C
u
m
u
la
ti
ve
f
re
q
u
en
cy
o
f
re
sp
o
n
d
in
g
FR
Brief pauses
after each
reinforcer is
delivered.
VI
Responding
occurs at
a fairly
constant
rate.
FI
Few
responses
immediately
after each
reinforcer is
delivered.
VR
No pauses
after each
reinforcer is
delivered.
Fixed ratio
Variable ratio
Fixed interval
Variable interval
R
es
p
o
n
se
s
Time
FIGURE 4.4
Reinforcement Schedules
The graphs show typical patterns of
responding produced by four different
schedules of reinforcement. (The hash
marks indicate when reinforcement is
delivered.) Notice that the steeper angle
of the top two graphs shows how the ratio
schedules usually produce more
responses over a given period of time
than do the interval schedules.

148 C H A P T E R 4 Learning and Human Nurture
kinds of status symbols. In fact, virtually any stimulus can become a secondary or
conditioned reinforcer by being associated with a primary reinforcer. With strong con-
ditioning, secondary reinforcers such as money, status, or awards can even become
ends in themselves.
Piggy Banks and Token Economies The distinction between primary and second-
ary reinforcers brings up a more subtle point: Just as we saw in classical conditioning,
operant conditioning is not pure learning, but it is built on a biological base; hence our
“wired-in” preferences for certain reinforcers—to which “junk” food manufacturers
pander with their sweet and fatty treats.
To illustrate the power of biology in operant conditioning, we offer the story of
Keller and Marian Breland, two students of Skinner’s who went into the animal train-
ing business, but encountered some unexpected trouble with their trained pigs. As you
may know, pigs are very smart animals. Thus, the Brelands had no difficulty teaching
them to pick up round wooden tokens and deposit them in a “piggy bank.” The prob-
lem was that, over a period of weeks, these porcine subjects reverted to piggish behav-
ior: They would repeatedly drop the token, root at it, pick it up and toss it in the air,
and root it some more. This happened in pig after trained pig. Why? Because rooting is
instinctive behavior for pigs. The Brelands (1961) found similar patterns in critters as
diverse as raccoons, chickens, whales, and cows, and coined the term instinctive drift to
describe this tendency for innate response tendencies to interfere with learned behavior.
No wonder, then, people can’t make their cats stop scratching the furniture—or can’t
altogether avoid the temptation of junk food.
Happily, psychologists have had better luck using tokens with people than with
pigs. Mental institutions, for example, have tapped the power of conditioned reinforc-
ers by setting up so-called token economies to encourage desirable and healthy patient
behaviors. Under a token economy, staff may reinforce grooming or taking medication
with plastic tokens. Patients soon learn they can exchange the tokens for highly desired
rewards and privileges (Ayllon & Azrin, 1965; Holden, 1978). Alongside other forms
of therapy, token economies help mental patients learn strategies for acting effectively
in the world (Kazdin, 1994).
Preferred Activities as Reinforcers: The Premack Principle The opportunity to
perform desirable activities can reinforce behavior just as effectively as food or drink
or other primary reinforcers. For example, people who exercise regularly might use a
daily run or fitness class as a reward for getting other tasks done. Likewise, teachers
have found that young children will learn to sit still if such behavior is reinforced with
the opportunity to run around and make noise later (Homme et al., 1963).
The principle at work here says the opportunity to engage in a preferred activity
(active, noisy play) can be used to reinforce a less-preferred behavior (sitting still and
listening to the teacher). Psychologists call this the Premack principle, after its discoverer.
David Premack (1965) first demonstrated this concept in thirsty rats, which would spend
more time running in an exercise wheel if the running were followed by an opportunity
to drink. Conversely, another group of rats that were exercise deprived, but not thirsty,
would increase the amount they drank if drinking were followed by a chance to run in
the wheel. In exactly the same way, then, parents can use the Premack principle to get
children to make the bed or do the dishes if the task is followed by the opportunity to
play with friends. What preferred activity can you use to reinforce yourself for studying?
Reinforcement Across Cultures The laws of operant learning apply to all creatures
with a brain. The biological mechanism underlying reinforcement is, apparently, much
the same across species. On the other hand, exactly what serves as a reinforcer varies
widely. Experience suggests that food for a hungry organism and water for a thirsty
one will act as reinforcers because they satisfy basic needs related to survival. But what
any particular individual will choose to satisfy those needs may depend as much on
learning as on survival instincts—especially in humans, where secondary reinforcement
is so important. For us, culture plays an especially powerful role in determining what
C O N N E C T I O N CHAPTER 9
The brain’s reward system
provides greater rewards for sweet
and fatty foods, a preference that
evolved from our ancestors’ need
for calorie-dense food to sustain
them through times when food
was scarce (p. 377).
instinctive drift The tendency of an organism’s
innate (instinctive) responses to interfere with learned
behavior.
token economy A therapeutic method, based
on operant conditioning, by which individuals are
rewarded with tokens, which act as secondary rein-
forcers. The tokens can be redeemed for a variety of
rewards and privileges.
Premack principle The concept, developed by
David Premack, that a more-preferred activity can be
used to reinforce a less-preferred activity.

How Do We Learn New Behaviors By Operant Conditioning? 149
will act as reinforcers. So while people in some cultures would find eating a cricket
reinforcing, most people of Euro-American ancestry would not. Similarly, disposing of
a noisy cricket might seem both sensible and rewarding to a Baptist, yet aversive to a
Buddhist. And, just to underscore our point, we note that watching a game of cricket
would most likely be rewarding to a British cricket fan—although punishingly dull to
most Americans.
So culture shapes preferences in reinforcement, but reinforcement also shapes cul-
ture. When you first walk down a street in a foreign city, all the differences that catch
your eye are merely different ways people have found to seek reinforcement or avoid
punishment. A temple houses cultural attempts to seek rewards from a deity. Clothing
may reflect attempts to seek a reinforcing mate or to feel comfortable in the climate.
And a culture’s cuisine evolves from learning to survive on the native plant and animal
resources. In this sense, then, culture is a set of behaviors originally learned by operant
conditioning and shared by a group of people.
The Problem of Punishment
Punishment as a means of influencing behavior poses several difficulties, as
schoolteachers and prison wardens will attest. Ideally, we might think of punishment
as the opposite of reinforcement: an aversive consequence used to weaken the behavior
it follows. And like reinforcement, punishment comes in two main forms. Positive
punishment requires application of an aversive stimulus—as, when you touch a hot
plate, the painful consequence reduces the likelihood of you repeating that behavior.
The other main form of punishment, negative punishment, results from the removal
of a reinforcer—as when parents take away a misbehaving teen’s car keys. (You can
see, then, that the terms positive and negative, when applied to punishment, operate
the same way they do when applied to reinforcement: Positive punishment adds
something, and negative punishment takes something away.) Technically, however—
and this is one of the problems of punishment—an aversive stimulus is punishing only
if it actually weakens the behavior it follows. In this sense, then, spankings or speeding
tickets may or may not be punishment, depending on the results.
Punishment versus Negative Reinforcement You have probably noted that
punishment and negative reinforcement both involve unpleasant stimuli. How can
you distinguish between the two? Let’s see how punishment and negative reinforce-
ment differ, using the following examples (see Figure 4.5). Suppose an animal in a
punishment An aversive consequence which,
occurring after a response, diminishes the strength of
that response. (Contrast with negative reinforcement.)
positive punishment The application of an
aversive stimulus after a response.
negative punishment The removal of an
attractive stimulus after a response.
loud noise
no noise
press lever
Consequence
loud noise removed
(negative reinforcement)
loud noise applied
(punishment)press lever
Response
FIGURE 4.5
Negative Reinforcement and Punishment Compared
Entomophagy is the practice of eating
insects as food, which people in some
cultures find reinforcing.

150 C H A P T E R 4 Learning and Human Nurture
Skinner box can turn off a loud, unpleasant noise by pressing a lever. This response pro-
duces negative reinforcement. Now compare that with the other animal in Figure 4.5
for which the loud noise serves as a punishment for pressing the lever.
The main point is this: Punishment and negative reinforcement lead to opposite effects
on behavior (Baum, 1994). Punishment decreases a behavior or reduces its probability
of recurring. In contrast, negative reinforcement—like positive reinforcement—always
increases a response’s probability of occurring again. And don’t forget the descriptors
positive and negative mean “add” and “remove.” Thus, both positive reinforcement and
positive punishment involve administering or “adding” a stimulus. On the other hand,
negative reinforcement and negative punishment always involve withholding or remov-
ing a stimulus. For a concise summary of the distinctions between positive and negative
reinforcement and punishment, please see Table 4.1.
Uses and Abuses of Punishment Many societies rely heavily on punishment and the
threat of punishment to keep people “in line.” We fine people, spank them, and give them
bad grades, parking tickets, and disapproving looks. Around the world and throughout
history, cultures have ritually engaged in shunning, stoning, flogging, imprisonment, and
a veritable smorgasbord of creative methods of execution in attempts to deter unaccept-
able behavior. Currently, American jails and prisons contain more than 2 million people,
while the United States currently maintains one in every 32 of its citizens in jail or prison
or on probation or parole (Bureau of Justice Statistics, 2009).
Why do we use punishment so often? For one, it can sometimes produce an
immediate change in behavior—which, incidentally, reinforces the punisher. For another,
punishers may feel satisfaction by delivering the punishment, sensing they are “settling
a score,” “getting even,” or making the other person “pay.” This is why we speak of
revenge as being “sweet,” a sentiment that seems to underlie public attitudes toward the
punishment of lawbreakers (Carlsmith, 2006).
But punishment—especially the sort of punishment involving pain, humiliation, or
imprisonment—usually doesn’t work as well in the long run (American Psychological
Association, 2002b). Punished children may continue to misbehave; reprimanded em-
ployees may sabotage efforts to meet production goals. And people still commit crimes
around the world, despite a variety of harsh punishment tactics. So why is punishment
so difficult to use effectively? There are several reasons.
First, punishment—unlike reinforcement—must be administered consistently. Driv-
ers will observe the speed limit when they know the highway patrol is watching; Andre
will refrain from hitting his little brother when a parent is within earshot; and you will
probably give up your wallet to a mugger who points a gun at you. But the power of
punishment to suppress behavior usually disappears when the threat of punishment is
removed (Skinner, 1953). If punishment is unlikely, it does not act as a deterrent—and in
most cases, it is impossible to administer punishment consistently. Intermittent punishment
is far less effective than punishment delivered after every undesired response: In fact, not
Apply (add) Stimulus (positive) Remove (subtract) Stimulus (negative)
What is the effect
of the stimulus
(consequence) on
behavior?
The probability of the
behavior increases.
Positive reinforcement
Example: An employee gets a bonus for good
work (and continues to work hard).
Negative reinforcement
Example: You take aspirin for your headache, and
the headache vanishes (so you take aspirin the
next time you have a headache).
The probability of the
behavior decreases.
Positive punishment
Example: A speeder gets a traffic ticket (and
drives away more slowly).
Negative punishment
Example: A child who has stayed out late misses
dinner (and comes home early next time).
Three important points to keep in mind as you study this table:
1. “Positive” and “negative” mean that a stimulus (consequence) has been added (presented) or subtracted (removed). These terms have nothing to do with “good”
or “bad, pleasurable or painful.”
2. We can often predict what effect a particular consequence will have, but the only way to know for sure whether it will be a reinforcer or a punisher is to observe its effect on
behavior. For example, although we might guess that a spanking would punish a child, the attention might actually serve as a reinforcer to strengthen the unwanted behavior.
3. From a cognitive viewpoint, we can see that reinforcement consists of the presentation of a pleasant stimulus or the removal of an unpleasant one. Similarly,
punishment entails the presentation of an unpleasant stimulus or the removal of a pleasant one.
TABLE 4.1 Four Kinds of Consequences
�

How Do We Learn New Behaviors By Operant Conditioning? 151
punishing an occurrence of unwanted behavior can have
the effect of rewarding it—as when a supervisor over-
looks the late arrival of an employee. In general, you can
be certain of controlling someone’s behavior through
punishment or threat of punishment only if you can
control the environment all the time. Such total control
is rarely feasible.
Second, the lure of rewards may make the possi-
bility of punishment seem worth the price. This may
be one factor impacting drug dealing—when the pos-
sibility of making a large amount of money outweighs
the possibility of prison time (Levitt & Dubner, 2005).
And, in a different way, the push-pull of punishment
and rewards also affects dieters, when the short-term
attraction of food may overpower the unwanted long-
term consequences of weight gain. So if you attempt to
control someone’s behavior through punishment, you
may fail if you do not control the rewards as well.
Third, punishment triggers escape or aggression. When punished, an organism’s
survival instinct prompts it to flee from or otherwise avoid further punishment. And
if escape is blocked, aggression can result. Corner a wounded animal, and it may sav-
agely attack you. Put two rats in a Skinner box with an electrified floor grid, and the
rats will attack each other (Ulrich & Azrin, 1962). Put humans in a harsh prison envi-
ronment, and they may riot—or, if they are prison guards, they may abuse the prisoners
(Zimbardo, 2004b, 2007).
Further, in a punitive environment, whether it be a prison, a school, or a home,
people learn that punishment and aggression are legitimate means of influencing oth-
ers. The punishment–aggression link also explains why abusing parents so often come
from abusive families, and why aggressive delinquents frequently come from homes
where aggressive behavior is commonplace (Golden, 2000). Unfortunately, the well-
documented relationship between punishment and aggression remains widely unknown
to the general public.
Here’s a fourth reason why punishment is so often ineffective: Punishment makes
the learner fearful or apprehensive, which inhibits learning new and more desirable
responses. Unable to escape punishment, an organism may eventually give up its
attempts at flight or fight and surrender to an overwhelming feeling of hopelessness.
This passive acceptance of a punitive fate produces a behavior pattern called learned
helplessness (Overmier & Seligman, 1967). In people, this reaction can produce the
mental disorder known as depression (Terry, 2000).
If you want to produce a constructive change in attitudes and behavior, learned
helplessness and depression are undesirable outcomes. The same goes for aggression
and escape. And, perhaps most importantly, punishment fails to teach learners what
to do differently, because it focuses attention on what not to do. All of these outcomes
interfere with new learning. By contrast, individuals who have not been punished feel
much freer to experiment with new behaviors.
Yet a fifth reason why punitive measures may fail: Punishment is often applied
unequally, even though that violates our standards of fair and equal treatment. For
example, parents and teachers punish boys more often than girls (Lytton & Romney,
1991). Then, too, children (especially grade school children) receive more physical pun-
ishment than do adults. And, to give one more example, our schools—and probably
our society at large—more often punish members of minority groups than members of
the majority (Hyman, 1996).
Does Punishment Ever Work? In limited circumstances, punishment can work
remarkably well. For example, punishment can halt the self-destructive behavior of
children with autism, who may injure themselves severely in some cases by banging
their heads or chewing the flesh off their fingers. A mild electric shock or a splash of
cold water in the face can quickly stop such unwanted behavior, although effects may be
C O N N E C T I O N CHAPTER 11
In the Stanford Prison
Experiment, the behavior of
normal, healthy college men
changed drastically after just a
few days in a simulated prison
environment (p. 500).
C O N N E C T I O N CHAPTER 14
Learned helplessness was
originally found in dogs that,
when repeatedly unable to escape
shocks in their cages, eventually
gave up and stopped trying.
Learned helplessness has been
documented widely in humans,
including abused and discouraged
children, battered wives, and
prisoners of war (p. 624).
Prison riots and other aggressive
behavior may result from highly punitive
conditions.

152 C H A P T E R 4 Learning and Human Nurture
temporary (Holmes, 2001). It can also be combined effectively with reinforcement—as when
students receive good grades for studying and failing grades for neglecting their work.
Punishment is also more likely to be successful if it involves a logical consequence:
a consequence closely related to the undesirable behavior—as contrasted with an
unrelated punishment, such as spanking or grounding. So, if a child leaves a toy truck
on the stairs, a logical consequence might be to lose the toy for a week. To give another
example, a logical consequence of coming home late for dinner is getting a cold dinner.
Rather than a purely punitive approach to misbehavior, research supports the com-
bination of logical consequences, extinction, and the rewarding of desirable alternative
responses. When you do decide to use punishment, it should meet the following conditions:
• Punishment should be swift—that is, immediate. Any delay will impair its effec-
tiveness, so “You’ll get spanked when your father gets home” is a poor punish-
ment strategy.
• Punishment should be consistent—administered every time the unwanted response
occurs. When bad behavior goes unpunished, the effect can actually be rewarding.
• Punishment should be limited in duration and intensity—meaningful enough to
stop the behavior but appropriate enough to “make the punishment fit the crime.”
• Punishment should clearly target the behavior and be a logical consequence of the
behavior rather than an attack on character of the person (humiliation, sarcasm,
or verbal abuse) or physical pain.
• Punishment should be limited to the situation in which the response occurred.
• Punishment should not give mixed messages to the punished person (such as, “You
are not permitted to hit others, but I am allowed to hit you”).
• The most effective punishment is usually negative punishment, such as loss of
privileges, rather than the application of unpleasant stimuli such as a spanking.
A Checklist for Modifying Operant Behavior
Think of someone whose behavior you would like to change. For the sake of illustra-
tion, let’s consider your niece Maddy’s temper tantrums, which seem to be occurring
with greater frequency—sometimes even when you take her out in public. Operant
conditioning offers a selection of tools that can help: positive reinforcement on a vari-
ety of schedules, plus negative reinforcement, extinction, and punishment.
• Since positive reinforcement is always good bet, identify and encourage a desir-
able behavior in place of the unwanted behavior. The most effective parents and
teachers often do this by shifting the child’s attention to some other reinforcing
activity. When taking her to the grocery store, for example, involve her in simple
choices between, say, the green apples or the red ones. This keeps her interested,
which will help prevent a temper tantrum, and also gives you an opportunity to
provide positive reinforcement for her help (“Good idea, Maddy—I like the red
ones, too!”) And don’t overlook the Premack principle, which lets Maddy do
something she enjoys if she behaves for a certain period of time. (Incidentally, this
is where shaping comes into play: To be effective, you must set goals for Maddy
that are within her reach, so she can achieve them and reap the benefits of posi-
tive reinforcement. So, you might aim for just 20 minutes of good behavior at first,
then—after she has achieved it and been rewarded—gradually work up to longer
and longer periods of time.) Use continuous reinforcement at first, then scale back
to a combination of intermittent reinforcement schedules to keep her tantrum free.
• Negative reinforcement can be useful too. If, for example, one of Maddy’s house-
hold chores is taking out the trash, tell her you’ll do it for her if she can play nicely
with her sister (with no temper tantrums) that afternoon. That way, she avoids
something she’d rather not do, which reinforces her for good behavior. You may
have enjoyed negative reinforcement yourself if you’ve had a professor who let
you opt out of the final exam if your other exam scores were high enough or skip
a homework assignment if you’d achieved some other important goal in the class.

How Do We Learn New Behaviors By Operant Conditioning? 153
There are less effective applications of negative reinforcement, however. For
example, parents commonly use nagging to try to get their children to, say, clean
their rooms. In this scenario, parents nag until the room gets cleaned—thus, the
child cleans the room to stop or to avoid the nagging. While this may get the job
done, it’s generally not pleasant for anyone. Instead, behaviorists recommend
parents create positive reinforcers to provide incentives for the kids to clean their
rooms. By offering meaningful rewards or using the Premack principle to encour-
age desired behaviors, you accomplish the same behavioral change without the
tension that typically accompanies nagging or other aversive stimuli.
• Extinction guarantees a solution, but only if you control all the reinforcers. In
Maddy’s case, extinction comes from not giving in to the temper tantrum and not
giving her what she wants. Instead, you simply allow the tantrum to burn itself
out. This can be a challenge, since it means you must suffer through the tantrum,
maybe even feeling embarrassed if she’s throwing the tantrum in public. (Have you
ever wondered why children seem intuitively to pick the most public places for
such displays? Perhaps because they quickly learn they will be “rewarded” with
candy or attention from an exasperated parent who just wants them to stop—
which is another misuse of negative reinforcement!) Another problem with extinc-
tion, however, is that it may take a while, so extinction is not a good option if the
subject is engaging in dangerous behavior, such as playing in a busy street.
• Punishment may be tempting, but we have seen that it usually produces unwanted
effects, such as aggression or escape. In addition, punishment often damages the
relationship between the punisher and the person being punished and is difficult
to employ with unfailing consistency. If you do decide to punish Maddy for her
tantrums, make it a logical consequence, such as a “time out” in her room if she is
acting up at home—and doing so swiftly, but without undue harshness.
The best approach—often recommended by child psychologists—combines several tactics.
In Maddy’s case, this might involve both reinforcing her desirable behaviors and using
extinction or logical consequences on her undesirable ones. We encourage you to try these
strategies for yourself the next time you are dealing with someone whose behavior is
undesirable. And remember: The behavior you may want to change could be your own!
Operant and Classical Conditioning Compared
Now that we have examined the main features of operant and classical condition-
ing, let’s compare them side by side. As you can see in Table 4.2, the consequences
of behavior—especially rewards and punishments—distinguish operant conditioning
different from classical conditioning. But note this point of potential confusion: As the
example in Figure 4.6 shows, food acts as a reward in operant conditioning, but in
TABLE 4.2 Classical and Operant Conditioning Compared
Classical Conditioning Operant Conditioning
Behavior is controlled by stimuli that precede
the response (by the CS and UCS).
Behavior is controlled by consequences
(rewards, punishments, and the like) that
follow the response.
No reward or punishment is involved (although
pleasant and aversive stimuli may be used).
Often involves reward (reinforcement)
or punishment.
Through conditioning, a new stimulus (the CS)
comes to produce “old” (reflexive) behavior.
Through conditioning, a new stimulus
(a reinforcer) produces new behavior.
Extinction is produced by withholding the UCS. Extinction is produced by withholding
reinforcement.
Learner is passive (responds reflexively):
Responses are involuntary. That is, behavior is
elicited by stimulation.
Learner is active (operant behavior): Responses
are voluntary. That is, behavior is emitted by the
organism.

154 C H A P T E R 4 Learning and Human Nurture
classical conditioning, food is an unconditioned stimulus. The important thing to note
is that in classical conditioning the food comes before the response—and therefore it
cannot serve as a reward.
Because classical conditioning and operant conditioning differ in the order in which
the stimulus and response occur, classically conditioned behavior is largely a response
to past stimulation. (Think of Pavlov’s dogs salivating after hearing a bell.) Operant
behavior aims to attain some future reinforcement or avoid a punishment. (Think of a
dog sitting to get a food reward.) To say it another way, operant conditioning requires
a stimulus that follows the response, whereas classical conditioning ends with the
response (see Figure 4.7).
Unconditioned stimulus
(food)
Unconditioned response
(salivation to food)
Conditioned response
(salivation to tone previously paired
with food)
Classical Conditioning
Operant behavior
(sitting up)
Reinforcing stimulus
(food)
Operant Conditioning
Conditioned stimulus
(tone)
FIGURE 4.6
The Same Stimulus Plays Different
Roles in Classical Conditioning and
Operant Conditioning
The same stimulus (food) can play vastly
different roles, depending on which type
of conditioning is involved. In classical
conditioning, it can be the UCS, while
in operant conditioning it can serve as
a reinforcer for operant behavior. Note
also that classical conditioning involves
the association of two stimuli that occur
before the response. Operant condition-
ing involves a reinforcing (rewarding) or
punishing stimulus that occurs after the
response.
Classical Conditioning Operant Conditioning
UCS
“Look out!”
CS
snake
UCR
fear
behavior
CR
Consequence:
attentionFIGURE 4.7
Classical and Operant Conditioning
Can Work Together
A response originally learned through
classical conditioning can be main-
tained and strengthened by operant
reinforcement.

How Do We Learn New Behaviors By Operant Conditioning? 155
Another difference between the two types of conditioning is the kinds of behaviors
they target. Operant conditioning encourages new behaviors—whether they be making
beds, going to work, developing healthy eating habits, or studying for an exam. Classi-
cal conditioning, on the other hand, emphasizes eliciting old responses to new stimuli—
such as salivating at the sound of a bell or flinching at the sound of a dentist’s drill.
You may have also noticed that extinction works in slightly different ways in the
two forms of learning. In classical conditioning, extinction requires withholding the
unconditioned stimulus. In operant conditioning, extinction results from withholding
the reinforcer.
Operant conditioning and classical conditioning differ in several other important
ways, as you saw in Table 4.2 (page 153). For one, operant behavior is not based on an
automatic reflex action, as was the dog’s salivation or Little Albert’s crying. Accordingly,
operant behavior seems more “voluntary”—more under the control of the responder.
To paraphrase a proverb: You can stimulate a dog to salivation (a reflex), but you can’t
make it eat (an operant behavior).
But don’t make the mistake of thinking that classical and operant conditioning are
competing explanations for learning. They can be complementary. In fact, responses
originally learned by classical conditioning will often be maintained later by operant
conditioning. How? Consider a snake phobia. Suppose the fear of snakes was origi-
nally learned by classical conditioning when a snake (CS) was paired with a frighten-
ing UCS (someone yelling, “Look out!”). Once the phobic response is established, it
could be maintained and strengthened by operant conditioning, as when bystanders
give attention (positive reinforcement) to the fearful person (see Figure 4.7).
PSYCHOLOGY MATTERS
Using Psychology to Learn Psychology
You may have tried the Premack principle to encourage yourself to study more, per-
haps by saving TV time or a trip to the refrigerator until your homework was done. It
works for some people, but if it doesn’t work for you, try making the studying itself
more enjoyable and more reinforcing.
For most of us, getting together with people we like is reinforcing, regardless of the
activity. So, make some (not all) of your studying a social activity. That is, schedule a
time when you and another classmate or two can get together to identify and discuss
important concepts, and try to predict what will be on the next test.
In this cartoon, Pavlov’s dog is illustrating
voluntary behavior (operant conditioning)
by drooling in order to make Pavlov write
in his little book.

156 C H A P T E R 4 Learning and Human Nurture
And don’t focus just on vocabulary. Rather, try to discover the big picture—the
overall meaning of each section of the chapter. The Core Concepts are a good place to
start. Then you can discuss with your friends how the details fit in with the Core Con-
cepts. You will most likely find that the social pressure of an upcoming study group
(serving as an intermittent reinforcer) will help motivate you to get your reading done
and identify murky points. When you get together for your group study session, you
will discover that explaining what you have learned strengthens your own understand-
ing. In this way, you reap the benefits of a series of reinforcements: time with friends,
enhanced learning, and better performance on the exam.
4.3 KEY QUESTION
How Does Cognitive Psychology Explain Learning?
According to biologist J. D. Watson’s (1968) account in The Double Helix, he and
Francis Crick cracked the genetic code one day in a flash of insight following months
of trial and error. You may have had a similarly sudden, if less famous, insight when
solving a problem of your own. Such events present difficulties for strict behaviorists,
because they obviously involve learning but are hard to explain in terms of Pavlovian
or Skinnerian conditioning.
Many psychologists believe that an entirely different process, called cognitive learn-
ing, is responsible for such flashes of insight. From a cognitive perspective, learning
does not always show itself immediately in behavior. Instead, learning can be reflected
in mental activity alone—as the Core Concept for this section says:
Core Concept 4.3
According to cognitive psychology, some forms of learning must be
explained as changes in mental processes rather than as changes in
behavior alone.
The cognitive perspective says that our
cognitions can affect our mental health—
or our mental disorders.
4. RECALL: Give an example of something that serves as a
conditioned reinforcer for most people.
5. APPLICATION & ANALYSIS: Suppose you are trying to
teach Stevie not to hit his sister. What operant techniques
would you use? Also, explain why extinction would not be wise
in this case.
6. UNDERSTANDING THE CORE CONCEPT: What is a feature
of operant conditioning that distinguishes it from classical
conditioning?
Check Your Understanding
1. APPLICATION: Give an example of a response a pet dog or cat
might learn that could be explained by Thorndike’s law of effect.
2. APPLICATION: Give an example of negative reinforcement from
your own life.
3. APPLICATION: Suppose you have taught your dog to roll over for
the reward of a dog biscuit. Which schedule of reinforcement would
keep your dog responding the longest time?
a. continuous reinforcement
b. intermittent reinforcement
c. negative reinforcement
d. noncontingent reinforcement
Answers 1. Any response that was learned by being rewarded—such as sitting up for a food reward or scratching at the door to be let into the house—
involves Thorndike’s law of effect. 2. Negative reinforcement occurs any time your behavior causes an unpleasant stimulus to stop bothering you.
Examples include taking aspirin to stop a pain, going to the dentist for a toothache, or doing your chores to stop a roommate from nagging you. 3. b
4. Money is probably the most common example. 5. The best approach is probably some combination of reinforcing alternative responses and “time
out” for hitting behavior. Under extinction alone, Stevie would still continue to hit his sister for a period of time until the behavior is extinguished,
which might inflict hardship on the sister. 6. In operant conditioning, learning depends on stimuli that occur after the response. These stimuli
include rewards and punishments. By contrast, classical conditioning focuses on stimuli that occur before the response.
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How Does Cognitive Psychology Explain Learning? 157
Let’s see how cognitive psychologists have approached this
task of examining the covert mental processes behind learning.
To do so, we first take you on a trip to the Canary Islands, off the
coast of northern Africa.
Insight Learning: Köhler in the Canaries with Chimps
Isolated on the island of Tenerife during World War I, Gestalt psy-
chologist Wolfgang Köhler (KER-ler) had time to think long and
hard about learning. Disenchanted with the behaviorists’ explana-
tion for learning, Köhler sought to develop his own theories. To
his way of thinking, psychology had to recognize mental processes
as an essential component of learning, even though mental events
had been spurned as subjective speculation by the behaviorists. To
press his point, Köhler took advantage of a primate research fa-
cility constructed by the German government on Tenerife. There,
he contrived experiments designed to reveal cognitive learning in
observable behavior (Sharps & Wertheimer, 2000; Sherrill, 1991).
In a series of famous studies, Köhler showed that chimps could learn to solve com-
plex problems, not just by trial and error (an explanation favored by behaviorists) but
by “flashes of insight” that combined simpler responses learned previously. One such
experiment involved Sultan, a chimp that had learned to pile up boxes and scramble on
top of them to reach fruit suspended high in his cage, and to use sticks to obtain fruit
that was just out of reach. When Köhler presented Sultan with a novel situation that
combined the two problems—with fruit suspended even higher in the air—the chimp
first attacked it unsuccessfully with sticks in trial-and-error fashion. Then, in apparent
frustration, Sultan threw the sticks away, kicked the wall, and sat down. According to
Köhler’s report, the animal then scratched his head and began to stare at some boxes
nearby. After a time of apparent “thinking,” he suddenly jumped up and dragged a box
and a stick underneath the fruit, climbed on the box, and knocked down his prize with
the stick.
Remarkably, Sultan had never before seen or used such a combination of responses.
This behavior, Köhler argued, was evidence that animals were not just mindlessly using
conditioned responses but were learning by insight: by reorganizing their perceptions
C O N N E C T I O N CHAPTER 3
Gestalt psychology is best
known for its work on
perception (p. 118).
The ruins of Köhler’s old laboratory,
known as La Casa Amarilla (the Yellow
House), can still be seen near the town
of Puerto de La Cruz. You can see a
satellite view of it using the following
coordinates in Google Earth: latitude
28° 24952.230 N and longitude
16° 31947.930 W. If you enjoy historical
mysteries, you might read A Whisper of
Expionage, a book exploring the
possibility that Köhler was not only
studying chimpanzee behavior but also
spying on Allied shipping from his
laboratory’s vantage point on the coast of
Tenerife during World War I (Ley, 1990).
The sort of learning displayed by Köhler’s chimps defied explanation by the behaviorists—in terms of classical conditioning and operant condition-
ing. Here, you see Sultan, Köhler’s smartest animal, solving the problem of getting the bananas suspended out of reach by stacking the boxes and
climbing on top of them. Köhler claimed that Sultan’s behavior demonstrated insight learning.

158 C H A P T E R 4 Learning and Human Nurture
of problems. He ventured that such behavior shows how apes, like humans, learn to
solve problems by suddenly perceiving familiar objects in new forms or relationships—
a decidedly mental process rather than a merely behavioral one. He called this insight
learning (Köhler, 1925). Insight learning, said Köhler, results from an abrupt reorgani-
zation of the way a situation is perceived.
Behaviorism had no convincing explanation for Köhler’s demonstration. Neither
classical nor operant conditioning could account for Sultan’s behavior in stimulus–
response terms. Thus, the feats of Köhler’s chimps demanded the cognitive explanation
of perceptual reorganization.
Cognitive Maps: Tolman Finds Out What’s on a Rat’s Mind
Not long after Köhler’s experiments with chimpanzees, the rats in Edward Tolman’s
lab at Berkeley also began behaving in ways that flew in the face of accepted behavioral
doctrine. They would run through laboratory mazes as if following a mental “map” of
the maze, rather than mindlessly executing a series of learned behaviors. Let’s see how
Tolman managed to demonstrate these “mindful” responses.
Mental Images—Not Behaviors If you have ever walked through your house in
the dark, you have some idea what Tolman meant by “cognitive map.” Technically, a
cognitive map is a mental image an organism uses to navigate through a familiar en-
vironment. But could a simple-minded creature like a rat have such complex mental
imagery? And, if so, how could the existence of these cognitive maps be demonstrated?
A cognitive map, Tolman argued, was the only way to account for a rat quickly select-
ing an alternative route in a maze when the preferred path to the goal is blocked. In
fact, rats will often select the shortest detour around a barrier, even though taking that
particular route was never previously reinforced. Rather than blindly exploring dif-
ferent parts of the maze through trial and error (as behavioral theory would predict),
Tolman’s rats behaved as if they had a mental representation of the maze. (Figure 4.8
shows the arrangement of such a maze.)
In further support of his claim that learning was mental, not purely behavioral,
Tolman offered another experiment: After his rats had learned to run a maze, he
flooded it with water and showed that the rats were quite capable of swimming through
insight learning A form of cognitive learning,
originally described by the Gestalt psychologists, in
which problem solving occurs by means of a sudden
reorganization of perceptions.
cognitive map In Tolman’s work, a cognitive map
was a mental representation of a maze or other physi-
cal space. Psychologists often use the term cognitive
map more broadly to include an understanding of con-
nections among concepts. Thus, a cognitive map can
represent either a physical or a mental “space.”
Path 2
A
Path 3
Path 1
Food
boxStart
B
FIGURE 4.8
Using Cognitive Maps in Maze
Learning
Rats used in this experiment preferred
the direct path (Path 1) when it was
open. When it was blocked at A, they pre-
ferred Path 2. When Path 2 was blocked
at B, the rats usually chose Path 3. Their
behavior indicated that they had a cogni-
tive map of the best route to the food box.
Source: Tolman, E. C. & Honzik, C. H. (December
1930). Degrees of hunger, reward and nonreward,
and maze learning in rats. University of California
Publication of Psychology, 4(16).

How Does Cognitive Psychology Explain Learning? 159
the maze. Again, this demonstrated what the animals had learned was a concept, not
just behaviors. Instead of learning merely a sequence of right and left turns, Tolman
argued, they had acquired a more abstract mental representation of the maze’s spatial
layout (Tolman & Honzik, 1930; Tolman et al., 1946).
Learning without Reinforcement In yet another study that attacked the very foun-
dations of behaviorism, Tolman (1948) allowed his rats to wander freely about a maze
for several hours. During this time, the rats received no rewards at all—they simply ex-
plored the maze. Yet, despite the lack of reinforcement, which behaviorists supposed to
be essential for maze learning, the rats later learned to run the maze for a food reward
more quickly than did other rats that had never seen the maze. Obviously, they had
learned the maze during the exploratory period, even though no hint of learning could
be seen in their behavior at the time. Tolman called this latent learning.
The Significance of Tolman’s Work As with Köhler’s experiments, what made
Tolman’s work both significant and provocative was its challenge to the prevailing
views of Pavlov, Watson, and other behaviorists. While Tolman accepted the idea that
psychologists must study observable behavior, he showed that simple associations
between stimuli and responses could not explain the behavior observed in his experi-
ments. Tolman’s cognitive explanations, therefore, presented a provocative challenge
to behaviorism (Gleitman, 1991).
Subsequent experiments on cognitive maps in rats, chimpanzees, and humans have
broadly supported Tolman’s work (Olton, 1992). More recently, brain imaging has pointed
to the hippocampus as a structure involved in “drawing” the cognitive map in the brain
(Jacobs & Schenk, 2003). So it seems clear that Tolman was on target: Organisms learn
the spatial layout of their environments by exploration and do so even if they are not rein-
forced for exploring. From an evolutionary perspective, the ability to make cognitive maps
would be highly adaptive in animals that must forage for food (Kamil et al., 1987).
In the following section, we shall see that Albert Bandura followed in Tolman’s
footsteps by toppling yet another pillar of behaviorism: the idea that rewards and pun-
ishments act only on the individual receiving them. Bandura proposed that rewards
and punishments can be effective even if we merely see someone else get them. (This
is why casinos make such a fuss over jackpot winners.) Bandura’s work, then, sug-
gests the consequences of behavior can operate indirectly, through observation. Let’s
see how he demonstrated this idea.
Observational Learning: Bandura’s Challenge to Behaviorism
Does observing violent behavior make viewers more likely to become violent? A clas-
sic study by Albert Bandura suggests that it does—at least in the children he invited to
his lab for a simple experiment. All it took to bring out aggressive behavior in these
children was watching adults appearing to enjoy punching, hitting, and kicking an
inflated plastic clown (a BoBo doll). When later given the opportunity, children who
had seen the adult models showed far more aggressive behavior toward the doll than
did children in a control condition who had not observed the aggressive models
(Bandura et al., 1963). Subsequent studies have shown similar results: Children will
imitate aggressive behaviors they have seen on television or in video games, exhibiting
up to seven times more aggressive acts than children in a control condition—even when
the models are merely cartoon characters (Anderson et al., 2007; Boyatzis et al., 1995).
Learning by Observation and Imitation An important implication of Bandura’s
BoBo doll study is that learning by observation and imitation can affect our behavior
in new situations—when we have no personal experience. Thus, learning can occur
not only by direct experience but also by watching the behavior of another person or
model. If the model’s actions appear successful—that is, if the model seems to find it
reinforcing—we may behave in the same way. In this way, learning by observation and
imitation is an extension of operant conditioning, by which we observe someone else
getting rewards but act as though we had also received a reward.
C O N N E C T I O N CHAPTER 6
A concept is a mental category
we use to organize our thinking.
In Tolman’s experiments, his rats
demonstrated learning of the
concept of a maze (p. 216).
In the BoBo doll experiment, a boy and
girl imitate the aggressive behavior that
they have seen from an adult.
Bandura’s BoBo Doll
Experiment
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160 C H A P T E R 4 Learning and Human Nurture
Psychologists call this social learning or observational learning. It accounts for
children learning aggressive behavior by imitating aggressive role models who are
perceived as successful or admirable or who seem to be enjoying themselves. Obser-
vational learning also explains how people learn athletic skills, how to drive a car, and
how to behave with friends and then shift roles in a job interview. And it illuminates
changes in clothing fashions and the rapid spread of slang expressions.
Observational learning occurs in nonhuman species, too, as when a mother cat
teaches her kittens how to hunt. One study demonstrated that even a creature as
simple-brained as the octopus can learn from watching the behavior of other octopi
(Fiorito & Scotto, 1992). Not to be outdone, a clever bowerbird in an Australian na-
tional park achieved notoriety through observational learning by fooling tourists with
its imitation of a cell phone ringing (Winters, 2002).
Effects of Media Violence As you might have guessed, much of the research on
observational learning has focused on the impact of violence in film and video (Huesmann
et al., 2003). Predictably, the issue is a controversial one, because much of the evidence is
correlational (Anderson & Bushman, 2002). That evidence makes a credible case,
based on more than 50 studies showing that observing violence is associated with vio-
lent behavior. But does observing violence cause violent behavior? Or is it the other way
around: Could it be that violent people are drawn to violent films and videos?
Thanks to more than 100 experimental studies, experts now know that observing
violence truly does increase the likelihood of violent behavior (Huesmann & Moise,
1996; Primavera & Heron, 1996). In fact, the link between viewing violent media
and subsequent behavior aggression is stronger than the link between lead-based paint
and children’s IQ, and is nearly as strong as the link between cigarette smoking and
cancer (Bushman & Anderson, 2001). Viewers of media violence also show less emo-
tional arousal and distress when they subsequently observe violent acts—a habituation-
like condition known as psychic numbing (Murray & Kippax, 1979). Psychologist Elliot
Aronson argues that extensive media violence is one factor contributing to violent trag-
edies, such as the Columbine High School shootings (Aronson, 2000).
Not all imitation is harmful, of course. Thanks to imitation, we also learn about
charitable behavior, comforting others in distress, and driving on the legal side of the
road. In general, people learn much—both prosocial (helping) and antisocial (hurt-
ing) behaviors—through observation of others. This capacity to learn from watching
enables us to acquire behaviors efficiently, without going through tedious trial and er-
ror. So while observational learning is a factor in violent behavior, it also enables us to
learn socially useful behaviors by profiting from the mistakes and successes of others.
Observational Learning Applied to Social Problems Around the Globe Television is
one of the most powerful sources of observational learning—and not only of the undesir-
able sort we have just noted. Here at home, the long-running children’s program, Sesame
Street, uses such well-loved characters as Big Bird and Cookie Monster to teach language,
arithmetic, and courtesy through observational learning. And in Mexico, TV executive
Miguel Sabido has deliberately drawn on Bandura’s work in creating the popular soap
opera Ven Conmigo (Come with Me), which focuses on a group of people who connect
through a literacy class. After the initial season, enrollment in adult literacy classes in the
broadcast area shot up to nine times the level in the previous year (Smith, 2002b).
The idea was taken up by a nonprofit group, Populations Communications Interna-
tional, which has promoted it worldwide. As a result, television dramas are now aimed
not only at literacy but at promoting women’s rights, safe sex, and preventing HIV and
unwanted pregnancies. Such programs are wildly popular, reaching large numbers of de-
voted fans in dozens of countries and regions around the world, including Latin American,
Africa, South and East Asia, the Middle East, the Caribbean, and the Philippines. In China,
observers learn about the value of girls; in Tanzania, they learn that AIDS is transmitted by
people, not by mosquitoes; and in India, the programs question the practice of child mar-
riages. In the Caribbean, soap operas now promote responsible environmental practices.
Does it work? Very well, say professors Arvind Singhal and Everett Rogers (2002),
who are currently gathering data on such projects. Because of a soap opera broadcast in
observational learning A form of cognitive
learning in which new responses are acquired after
watching others’ behavior and the consequences of
their behavior.
C O N N E C T I O N CHAPTER 1
Only an experimental study can
determine cause and effect
(p. 27).

How Does Cognitive Psychology Explain Learning? 161
India, a whole village signed a letter promising to stop the practice of child marriages.
Similarly, Tanzanians now increasingly approve of family planning. And in rural villages
in India, the enrollment of girls in school has risen between ten and 38 percent. Overall,
it appears that television can be a means of producing positive social change and act as
a conduit for psychological research to make a significant difference in people’s lives.
Brain Mechanisms and Learning
What do we know about the biology behind learning? On the level of neurons, learning
apparently involves physical changes that strengthen the synapses in groups of nerve
cells—a process called long-term potentiation (Antonova et al., 2001; Kandel, 2000).
Initially, neurons in various brain areas involved in a learning task work very hard—
for example, as a person learns the location of various objects, cells in the visual and
parietal cortex may fire rapidly. But as learning progresses, the connections among the
different cortical regions become stronger and the firing pattern becomes less intense
(Büchel et al., 1999).
In operant conditioning, the brain’s reward circuitry comes into play, especially
in parts of the frontal cortex and the limbic system, rich in dopamine receptors
(O’Doherty et al., 2004; Roesch & Olson, 2004). Many experts now believe the brain
uses this circuitry to identify the rewards that are the essence of positive reinforcement
(Fiorillo et al., 2003; Shizgal & Avanitogiannis, 2003). The limbic system also helps us
remember strong emotions, such as fear, so often associated with classical conditioning
(Miller, 2004). And in the next chapter, when we talk about memory, you will learn
about other parts of the brain involved in learning.
The Brain on Extinction While it is important for our survival to remember
emotion-laden events, it’s also important to forget associations that turn out to be
irrelevant. So just as wild animals need to forget about a water hole that has run dry,
you must learn to deal with changes in school schedules or traffic laws. These examples
involve extinction of responses learned previously. Neuroscientists have found that
extinction occurs when certain neurotransmitters, including glutamate and norepi-
nephrine, block memories (Miller, 2004; Travis, 2004).
Discoveries such as these have stimulated the search for drugs that could accom-
plish something previously only seen in futuristic movies: blocking the emotional
trauma associated with certain events, such as combat experiences, violent crimes, and
horrific accidents. And recent research boasts early success (Brunet et al., 2007; Kindt
et al., 2009). In both animals and humans, experimenters have successfully eliminated
the emotional arousal associated with typical memories of such traumatic events. And
while this remarkable discovery holds great potential for survivors of violent crime,
war, accidents, and natural disasters, ethical questions remain about future directions
in this rapidly advancing field.
Linking Behavioral Learning with Cognitive Learning Neuroscience has found
evidence in the brain to support both the behaviorist and the cognitive explanations
for learning. Specifically, there may be two separate brain circuits for learning: one
for simple stimulus–response learning and one for more complex tasks (Kandel &
Hawkins, 1992). The simpler circuit seems responsible for the sort of “mindless” learn-
ing that occurs when a dog drools at the sound of a bell or when a person acquires a
motor skill, such as riding a bike or kicking a soccer ball. This kind of learning occurs
relatively slowly and improves with repetition over many trials. Significantly, classical
conditioning and much of operant learning fit this description. By contrast, the second
type of learning circuit seems responsible for more complex forms of learning requir-
ing conscious processing: concept formation, insight learning, observational learning,
and memory for specific events. If further research verifies that this division reflects a
fundamental distinction in the nervous system, we will be able to say that those on the
behavioral and cognitive extremes were both (partly) right. They were talking about
fundamentally different ways the brain learns (see Figure 4.3) (Clark & Squire, 1998;
Jog et al., 1999).
long-term potentiation A biological process
involving physical changes that strengthen the syn-
apses in groups of nerve cells that is believed to be the
neural basis of learning.
Although scientists have discovered
experimental methods of blocking the
emotional trauma associated with memo-
ries of a traumatic event, the notion of a
machine that can selectively delete mem-
ories (as in the film Eternal Sunshine
of the Spotless Mind) will likely remain
farfetched.
Billboards, television programs, and other
media campaigns can be effective tools
for promoting social change.

162 C H A P T E R 4 Learning and Human Nurture
Observational Learning and Mirror Neurons People obviously learn from their
observations of others, as we saw in Bandura’s BoBo doll studies. Similarly, if you see
someone at the dinner table take a bite and grimace with disgust, you will be reluctant
to taste the same dish. But the mystery has always been to understand how our brains
respond to somebody else’s rewards or punishments. The recent discovery of mirror
neurons suggests a neurological basis for observational learning. It may be that the
“mirror cells” in our brains are finely tuned to help us mirror other people’s sense of
being rewarded or punished by activating the same circuits in our own brains (Jaffe,
2007). Watch the news for further developments.
“Higher” Cognitive Learning
It now seems clear that much of the complex and abstract learning required in college
classes is fundamentally different from the learning that Pavlov, Watson, and Skinner
studied. Acquiring knowledge about the field of psychology, for example, involves
building mental images, assimilating concepts, and pondering ways they can be related.
It’s not that behavioral conditioning isn’t involved in human learning—after all,
students do work for grades and salivate when they see a pizza—but principles of be-
havioral learning don’t tell the whole story of “higher” cognitive learning.
The following chapters will take us deeper into this realm of cognitive learning,
where we will discuss memory, thinking, concept formation, problem solving, and intel-
ligence. There, you will learn more about mental structures that underlie cognition. The
challenge we will face is exactly the one behaviorists were hoping to avoid: In studying
cognition, we must make inferences about processes we cannot measure directly. We will
find, however, that cognitive psychologists have developed very clever methods for ob-
taining objective data on which to base their inferences. The newest of these—coming
fully online in the last decade or so—is brain imaging, which, as we will see, has brought
psychologists very close to an objective glimpse at private mental processes.
But before we move on to these topics in the next chapter, let’s return to the prob-
lem with which we began the chapter: Sabra’s fear of flying.
PSYCHOLOGY MATTERS
Fear of Flying Revisited
Which kind of learning—operant conditioning or classical conditioning—do you
suppose lay behind Sabra’s aversion to flying? Although we may never know exactly
what caused her fear in the first place, we can guess that both forms of conditioning
C O N N E C T I O N CHAPTER 2
Mirror neurons help us imitate
other people’s behavior (p. 70).
TABLE 4.3 Behavioral Learning and Cognitive Learning Compared
Behavioral Learning Cognitive Learning
Focus is on observable events (stimuli and
responses) only.
Inferences are made about mental processes that
are not directly observable.
Learning consists of associations among
stimuli and responses.
Learning as information processing: The learner
seeks useful information from stimuli.
Main forms of learning are habituation, classical
conditioning, and operant (instrumental)
conditioning.
Learning also involves insight, observational
learning, cognitive maps, and other more
complex forms of learning.
Developed as a rebellion against the subjective
methods of structuralism and functionalism:
Behaviorism became the dominant perspective
for much of the 20th century.
Developed as a rebellion against the narrow
perspective of behaviorism: Cognitive psychology
became the dominant perspective at the end of
the 20th century.
Big names include Pavlov, Thorndike, Watson,
and Skinner.
Big names include Köhler, Tolman, and Bandura.

How Does Cognitive Psychology Explain Learning? 163
were involved. Fears commonly arise through direct experience involving classical
conditioning. Alternatively, fears can be learned through observational learning,
perhaps from a fearful parent or peer. And once the fear has been learned, operant
conditioning can maintain it, because people are rewarded by avoiding the feared
object.
These assumptions have led some airlines to experiment with a hybrid treatment
known as cognitive-behavioral therapy, aimed at helping people overcome their fear of
flying. Happily, Sabra located one of these programs a few weeks before the conference
started. She contacted the airline and signed up for three weekend sessions to be held
at a nearby airport.
She arrived at the appointed time, full of expectations and apprehensions. Would
the therapist probe her childhood experiences and fantasies? Would she have to take
tranquilizers? Or would she have to undergo some sort of terrifying treatment, such as
flying upside down in a small airplane?
Her worst expectations turned out to be unfounded. The treatment sessions were
organized by a behavioral psychologist who gathered the nine participants in a small
conference room. He began by saying that such fears are learned—much as you might
learn to cringe when you hear a dentist’s drill. But because it is not important how
such fears originated, this fear-of-flying program would focus on the present, not the
past, he said. Sabra began to feel more relaxed.
The conditioning-based therapy program combined several learning strategies.
A classical conditioning component would involve extinction of her fear through
gradual exposure to the experience of flying. Operant conditioning would play a role
through social reinforcement from the therapist and other members of the group. In
addition, a cognitive component would involve learning more about how airplanes
work.
After a brief overview of the process they would experience over the next three
weeks, the group took a tour of the airport, including the cabin of a passenger jet
parked on the Tarmac. Then they went back to the conference room to learn about
how a pilot controls an airplane and about the physical forces that keep it in the air.
The group also watched some videos involving routine flights in a commercial jet. All
in all, this first session went smoothly, and everyone seemed much more at ease than
when they started.
The second weekend began with more classroom discussion. Then, the class
went back into the airliner, where they took seats and went through a series of re-
laxation exercises designed to extinguish the participants’ fears and to learn a new
and more relaxed response to the experience of being in an airplane. This training
included deep breathing and progressive relaxation of specific muscle groups all
over the body. When everyone in the group reported feeling relaxed, they again
watched videos of flight on the plane’s TV monitors. This was followed by more
relaxation exercises. The final activity for the second weekend involved starting the
engines and going through the preflight routine—all the way up to takeoff . . . and
more relaxation exercises.
The final weekend session was almost identical to the previous one. The only
difference was that “graduation” involved an actual flight—a 20-minute trip out
over the local countryside and back to the airport. It was, of course, voluntary, but
only one of the nine people in the class chose not to go. Sabra went, but not without
some anxiety. The therapist, however, encouraged the group to focus on the relax-
ation exercises they had learned rather than on their feelings of fear. To the amaze-
ment of all who participated, these learning-based techniques helped them through
the flight exercise without losing control of their emotional responses. Although no
one’s fear had vanished completely, everyone on board was able to bring it under
control.
The happiest result was that Sabra was able to go to her meeting in Hawaii—
where, by the way, she had a productive conference and a wonderful time. For our
purposes we should also note that she has flown several times since then. Each trip gets
a little easier, she says—just as the psychology of learning would predict.
Through cognitive-behavioral therapy,
Sabra learned new ways of thinking about
the experience of flying. Gradual exposure
to flying, called desensitization (a form
of extinction), also helped to banish her
fearful responses.

164 C H A P T E R 4 Learning and Human Nurture
CRITICAL THINKING APPLIED
Do Different People Have Different “Learning Styles”?
Without a doubt, people differ in the ways they approach learning. As you can see by observing your classmates, ev-
eryone brings a different set of interests, abilities, temperamental
factors, developmental levels, social experiences, and emotions
to bear on learning tasks. But can we say these differences con-
stitute distinct “learning styles”? For example, are some people
“visual learners” who need to see the material rather than hear-
ing it, as, perhaps, an “auditory learner” must do?
Educators have been drawn to the concept of learning
styles in the hope of encouraging learning by tailoring in-
struction to a student’s learning style. The excitement about
learning styles has, in turn, led to a proliferation of learning-
style inventories, each aiming to diagnose how a student
learns best, with implications for how to tailor a teaching
environment to fit each learner. Perhaps you have taken one
such test. But is all this buzz based on fact or fantasy?
What Are the Critical Issues?
From a critical perspective, the principal issue centers on the
meaning of “learning styles.” The term may seem intuitively
clear—but does it mean the same thing to everyone? And
are learning styles really requirements or mere preferences
for learning? In other words, if you are a “visual learner,” to
what extent does this truly impact your ability to learn when
visuals are not available? And are learning styles unchange-
able (like eye color), or can people adjust their approach to
learning to fit the demands of the subject matter (say, litera-
ture, psychology, dentistry, or music)?
What Is the Source? Unfortunately, most of the publications
on learning styles come from sources that have not performed the
controlled studies needed to support their claims (Stahl, 1999).
Rather, the “research” they say supports their claims is largely
unpublished and thus has not be scrutinized by other scientists.
As we learned in Chapter 1, publishing and critiquing studies
and their results is a key step in the scientific method. Avoiding
this requirement may be a warning sign that the claimant has
fallen prey to one or more types of bias and thus lacks credibility.
What Is the Evidence? One problem we encounter in ex-
amining the evidence for learning styles is that, even among
learning-style enthusiasts, we find no agreed-upon list of distinct
learning styles. Although educators commonly talk about “verbal
learners,” “visual learners,” and “kinesthetic (movement) learn-
ers,” some inventories also claim to assess some combination of
the following styles: tactile (touch), logical, social, solitary, active/
reflective, sensing/intuitive, thinking/feeling, judging/perceiving,
c. have children punch a BoBo doll to “get the aggression out of
their system.”
d. punish children for aggressive acts performed at school.
4. APPLICATION: Mirror neurons seem to explain how observational
learning works. So, looking at your answer to the previous question:
What would the observers’ mirror neurons be responding to?
5. UNDERSTANDING THE CORE CONCEPT: Pick one
experiment described in this section of the chapter, and discuss
why it is difficult to explain in purely behavioral terms.
Check Your Understanding
1. ANALYSIS: Why was insight rather than trial and error the best
explanation for Sultan’s solution to the problem of reaching the
food reward?
2. RECALL: What evidence did Tolman have that his rats had
developed cognitive maps of a maze?
3. APPLICATION: If you were going to use Bandura’s findings in
developing a program to prevent violence among middle school
children, you might
a. have children watch videos of children who are responding
constructively to aggressive acts on the playground.
b. punish children who are aggressive and reward those who are
not aggressive.
Answers 1. Sultan had apparently given up on active trial-and-error attempts to solve the problem. Yet, after a period of inactivity, he abruptly found
the solution, which involved piling the boxes so he could climb on them and reach the fruit. Köhler argued that Sultan had achieved the solution
mentally, through insight. 2. When their usual path was blocked, Tolman’s rats would usually take the shortest alternative path to the goal. 3. a 4. The
mirror neurons in the observers would be responding to the behavior of the children who are responding constructively to aggressive acts. 5. All of the
following are difficult to explain behaviorally because each challenges a basic principle of operant or classical conditioning: Köhler’s experiments on
insight learning (learning = a reorganization of perceptions), Tolman’s “cognitive map” experiments (evidence that animals learn concepts rather than
specific behaviors), and Bandura’s studies of observational learning (children learn behaviors for which other people are rewarded).
Study and Review at MyPsychLab

How Does Cognitive Psychology Explain Learning? 165
sequential/global. This widespread disagreement regarding even
the basic categories of “learning styles” should be a clue to the
critical thinker that claims may be based on mere speculation
and common sense rather than true scientific findings.
A second red flag we see when we examine the evidence
is the scarcity of findings to support any relationship between
a person’s learning style and his or her actual learning. In
fact, most advocates of learning styles have little support-
ing data for their claim that people with different scores learn
the same material in different ways. In fact, the research we
have shows that matching a teaching environment to a per-
son’s purported learning style has little to no effect on his
or her achievement. Thus, a more accurate interpretation
of learning styles may be that they reflect preferences in
learning rather than requirements for learning (Krätzig &
Arbuthnott, 2006).
There is, however, one scientific study that does show
evidence for impact of certain learning styles on achievement.
An ambitious program developed by cognitive psychologists
Robert Sternberg and Elena Grigorenko first measured stu-
dents’ abilities for logical, creative, and practical thinking—
arguably, three distinct forms of “intelligence” (Sternberg,
1994; Sternberg & Grigorenko, 1997). Then students in an
introductory psychology course were divided into groups that
received instruction emphasizing the form of intelligence on
which they had scored highest. (A control group of students
was deliberately mismatched.) Tests at the end of the course
indicated that students did best when the teaching emphasis
matched their intellectual style.
What was different about the Sternberg and Grigorenko
study? In addition to the fact that their results did show bet-
ter student achievement when the teaching style matched
their intellectual profile—in terms of logical, creative, and
practical thinking—they used a randomized, double-blind
experimental method to test their hypothesis. Notably, most
other “learning style assessments” fail to employ such rigor-
ous and reliable scientific procedures.
Does the Issue Require Multiple Perspectives? If learning
styles do exist, could a cross-cultural perspective help us under-
stand them (Winerman, 2006b)? Studies by Nisbett et al. (2003)
have shown that Asians and Americans often perceive the world
quite differently, with Americans focusing on central objects and
Asians taking in a scene more globally. (The difference is cul-
tural, not physiological: Americans of Asian ancestry perceive in
essentially the same way as do other Americans.) To illustrate the
difference in these two styles of “seeing,” look at the image of the
tiger against a jungle background on this page. Nisbett’s group
found that the typical American spends more mental energy on
putting prominent elements of the scene—the tiger—into logi-
cal categories, while Asians usually pay more attention to the
context and background—the jungle.
Culture can also influence the way people approach class-
room learning. For example, Americans generally believe that
academic success is the result of innate intelligence, while
East Asians emphasize discipline and hard work (Li, 2005).
Which belief system would you guess might encourage most
children to do well in school?
Other cultural differences can play a role in academic
achievement as well, says Korean-born psychologist Heejung
Kim. After struggling with classes that required group
discussion, which was rare in her Korean educational expe-
rience, Kim (2002) decided to look for differences between
the ways Asians and Americans approach academic tasks.
As she predicted, when Asian and American college students
were given problems to solve, the Americans usually bene-
fited from talking over the problems with each other, while
such discussion often inhibited problem solving by Asian
students.
We note, however, that these cultural differences are not
part of the current debate regarding “learning styles” and
thus have not been included in any of the learning styles in-
ventories marketed by a variety of organizations. We men-
tion them here, however, to show that ideas currently based
on popular opinion (such as the impact of learning styles on
performance) stand to gain credibility by accepting criticism
from the scientific community and using it to seek improve-
ments in their theories. In this case, advocates of learning
styles might do well to conduct controlled tests to investigate
whether some of these cultural differences might result in ac-
tual performance differences and, if so, create categories of
learning styles that truly reflect empirical differences.
What Conclusions Can We Draw?
In general, while we best be cautious about most claims
regarding learning styles, we should remain open to new
developments that may emerge from cross-cultural research
and from work on Sternberg’s three-intelligences theory.
Beyond that, we should acknowledge that interest in learn-
ing styles has encouraged teachers and professors to pres-
ent material in a variety of ways in their classes—including
media, demonstrations, and various “active learning” tech-
niques. Further, available research suggests everyone learns
better when the same material can be approached in more
than one way—both visual and verbal, as well as through
hands-on learning (McKeachie, 1990, 1997, 1999).
The lines on this image, used by Nisbett’s team, show one individual’s
eye movements when scanning the scene. Americans spent more time
looking at the tiger and other prominent objects in the picture, whereas
Asians spent more time scanning details of the context and background.

166 C H A P T E R 4 Learning and Human Nurture
the way we learn to the type of material to be learned: You
wouldn’t learn about music in exactly the same way you would
learn about math. Learning involves an interaction of many fac-
tors: the learner, the material, the medium in which the material
is presented, the organization of the presentation, the person-
alities of the teacher and learner, and the environment in which
learning takes place, to name a few. And your college experience
presents a wonderful opportunity to learn to think in new and
unaccustomed ways.
ADAPTING YOURSELF TO BETTER LEARNING
Most students would like to improve their
performance in one or more classes. Rather
than wasting time with the pseudoscience
of learning styles, try applying the bona fide
principles of classical and operant condition-
ing to a plan designed specifically to help
you achieve your goal. Using the various prin-
ciples you have learned so far in this chapter,
design your own behavior change program.
First, identify a specific behavior.
Instead of setting a broad goal, such as
getting a better grade, make your goal
specific—reading eight textbook pages per
day, completing the “As You Read Practice
Activities” in MyPsychLab, or reviewing your
class notes each day. Then identify at least
five ways you can encourage the new behav-
ior based on the principles of classical and
operant conditioning. For starters, you might
identify one feeling or biological stimulus
you want to associate with the desired be-
havior and figure out a way to achieve that
with classical conditioning. Then, you’ll def-
initely want to identify one or two reinforcers
you can use—continuously at first. Next,
decide what schedules of reinforcement
you will implement once you have begun
to shape the behavior successfully, and—
based on that—write down how often you
will receive a reinforcer and what it will be.
For best results, use a variety of reinforcers
on a variety of schedules to keep yourself re-
sponding well. Then get started! Keep track
of your progress, and make adjustments as
needed.
CHAPTER SUMMARY
CHAPTER PROBLEM: Assuming Sabra’s fear of flying was a
response she had learned, could it also be treated by learning? If
so, how?
• Classical conditioning played one role in Sabra overcoming
her fear of flying. By creating positive associations with the
experience of flying, Sabra underwent a combination of
extinction and counter-conditioning.
• Operant conditioning helped Sabra overcome her fear of flying
through shaping—providing positive reinforcement for each
successive step toward flying in an airplane. The effectiveness
of the treatment provided negative reinforcement by removing
the anxiety and fear she had previously associated with flying.
• Cognitive learning added instruction about some of the
aeronautical aspects of flying, thus helping Sabra develop
a mental understanding of how airplanes work, as well as
observational learning during which Sabra observed calm
passengers takng a flight.
But back to our main point: We recommend caution when
interpreting results of tests that purport to identify your learn-
ing style. Beware of people who tell you that you are a visual
learner, a reflective learner, or some other type: Just because you
prefer images to words, for example, does not mean that you
should avoid reading and just look at the pictures. This sort of
thinking erroneously suggests that each person learns in only
one way. It also erroneously suggests that the way we learn is
fixed and unchanging. Instead, we need to learn how to adapt
4.1 What Sort of Learning Does Classical
Conditioning Explain?
Core Concept 4.1 Classical conditioning is a basic form
of learning in which a stimulus that produces an innate reflex
becomes associated with a previously neutral stimulus, which
then acquires the power to elicit essentially the same response.
Learning produces lasting changes in behavior or mental pro-
cesses, giving us an advantage over organisms that rely more
heavily on reflexes and instincts. Some forms of learning, such
as habituation, are quite simple, while others, such as classical
conditioning, operant conditioning, and cognitive learning,
are more complex.
The earliest learning research focused on classical condi-
tioning, beginning with Ivan Pavlov’s discovery that condi-
tioned stimuli (after being paired with unconditioned stimuli)
could elicit reflexive responses. His experiments on dogs
showed how conditioned responses could be acquired and
extinguished and undergo spontaneous recovery in laboratory
animals. He also demonstrated stimulus generalization and dis-
crimination learning. John Watson extended Pavlov’s work to
people, notably in his famous experiment on the conditioning
Listen at MyPsychLabto an audio file of your chapter

of fear in Little Albert. More recent work, particularly studies
of taste aversions, suggests, however, that classical condition-
ing is not a simple stimulus–response learning process but also
has a biological component. In general, classical conditioning
affects basic, survival-oriented responses. Therapeutic applica-
tions of Pavlovian learning include the prevention of harmful
food aversions in chemotherapy patients.
acquisition (p. 138)
behavioral learning (p. 135)
classical conditioning (p. 136)
conditioned response (CR) (p. 138)
conditioned stimulus (CS) (p. 138)
extinction (in classical conditioning) (p. 138)
habituation (p. 135)
learning (p. 134)
mere exposure effect (p. 135)
neutral stimulus (p. 137)
spontaneous recovery (p. 138)
stimulus discrimination (p. 139)
stimulus generalization (p. 139)
unconditioned response (UCR) (p. 138)
unconditioned stimulus (UCS) (p. 137)
4.2 How Do We Learn New Behaviors
By Operant Conditioning?
Core Concept 4.2 In operant conditioning, the
consequences of behavior, such as rewards and punishments,
influence the probability that the behavior will occur again.
A more active form of learning, called instrumental condition-
ing, was first explored by Edward Thorndike, who established
the law of effect based on his study of trial-and-error learning.
B. F. Skinner expanded Thorndike’s work, now called operant
conditioning, to explain how responses are influenced by
their environmental consequences. His work identified and
assessed various consequences, including positive and nega-
tive reinforcement, punishment, and an operant form of extinc-
tion. The power of operant conditioning involves producing
new responses. To learn how this works, Skinner and others
examined continuous reinforcement as well as several kinds of
intermittent reinforcement contingencies, including FR, VR, FI,
and VI schedules. As for punishment, research has shown it is
more difficult to use than reinforcement because it has sev-
eral undesirable side effects. There are, however, alternatives,
including operant extinction and rewarding of alternative
responses, application of the Premack principle, and prompt-
ing and shaping new behaviors. These techniques have found
practical use in controlling behavior in schools and other
institutions, as well as in behavioral therapy for controlling
fears and phobias.
conditioned reinforcer or secondary
reinforcer (p. 147)
continuous reinforcement (p. 145)
extinction (in operant conditioning)
(p. 146)
fixed interval (FI) schedules (p. 147)
fixed ratio (FR) schedules (p. 146)
instinctive drift (p. 148)
intermittent reinforcement (p. 146)
interval schedule (p. 146)
law of effect (p. 143)
negative punishment (p. 149)
negative reinforcement (p. 144)
operant chamber (p. 144)
operant conditioning (p. 143)
positive punishment (p. 149)
positive reinforcement (p. 144)
Premack principle (p. 148)
primary reinforcer (p. 147)
punishment (p. 149)
ratio schedule (p. 146)
reinforcement contingencies
(p. 145)
reinforcer (p. 143)
schedule of reinforcement (p. 146)
shaping (p. 145)
token economy (p. 148)
variable interval (VI) schedule
(p. 147)
variable ratio (VR) schedule
(p. 147)
4.3 How Does Cognitive Psychology
Explain Learning?
Core Concept 4.3 According to cognitive psychology,
some forms of learning must be explained as changes in
mental processes rather than as changes in behavior alone.
Much research now suggests that learning is not just a process
that links stimuli and responses: Learning is also cognitive. This
was shown in Köhler’s work on insight learning in chimpanzees,
in Tolman’s studies of cognitive maps in rats, and in Bandura’s
research on observational learning and imitation in humans—
particularly the effect of observing aggressive models, which
spawned many studies on media violence and, recently, applica-
tions dealing with social problems, such as the spread of AIDS.
All this cognitive research demonstrates that learning does not
necessarily involve changes in behavior, nor does it require re-
inforcement. In the past three decades, cognitive scientists have
reinterpreted behavioral learning, especially operant and classi-
cal conditioning, in cognitive terms, as well as searched for the
neural basis of learning.
cognitive map (p. 158)
insight learning (p. 158)
long-term potentiation (p. 161)
observational learning (p. 160)
Chapter Summary 167

168 C H A P T E R 4 Learning and Human Nurture
CRITICAL THINKING APPLIED
however, is sparse. Nor is there general agreement on a specific
set of learning styles. A critical thinking approach suggests
that people have learning preferences, but they can learn to
adapt their approach to different kinds of material.
Do Different People Have Different “Learning Styles”?
Media attention on so-called learning styles continues to
encourage learners to focus on learning in ways that match
their learning style. Empirical evidence to support this notion,
DISCOVERING PSYCHOLOGY VIEWING GUIDE
Watch the following video by logging into MyPsychLab (www.mypsychlab.com).
After you have watched the video, answer the questions that follow.
PROGRAM 8: LEARNING
Program Review
6. What point is Professor Zimbardo making when he says “Relax”
while firing a pistol?
a. There are fixed reactions to verbal stimuli.
b. The acquisition process is reversed during extinction.
c. Any stimulus can come to elicit any reaction.
d. Unconditioned stimuli are frequently negative.
7. What point does Ader and Cohen’s research on taste aversion in
rats make about classical conditioning?
a. It can be extinguished easily.
b. It takes many conditioning trials to be effective.
c. It is powerful enough to suppress the immune system.
d. It tends to be more effective than instrumental conditioning.
8. What is Thorndike’s law of effect?
a. Learning is controlled by its consequences.
b. Every action has an equal and opposite reaction.
c. Effects are more easily changed than causes.
d. A conditioned stimulus comes to have the same effect as an
unconditioned stimulus.
9. According to John B. Watson, any behavior, even strong emotion,
could be explained by the power of
a. instinct.
b. inherited traits.
1. Which of the following is an example of a fixed-action
pattern?
a. a fish leaping at bait that looks like a fly
b. a flock of birds migrating in winter
c. a person blinking when something gets in her eye
d. a chimpanzee solving a problem using insight
2. What is the basic purpose of learning?
a. to improve one’s genes
b. to understand the world one lives in
c. to find food more successfully
d. to adapt to changing circumstances
3. How have psychologists traditionally studied learning?
a. in classrooms with children as participants
b. in classrooms with college students as participants
c. in laboratories with humans as participants
d. in laboratories with nonhuman animals as participants
4. In his work, Pavlov found that a metronome could produce
salivation in dogs because
a. it signaled that food would arrive.
b. it was the dogs’ normal reaction to a metronome.
c. it was on while the dogs ate.
d. it extinguished the dogs’ original response.
5. What is learned in classical conditioning?
a. a relationship between an action and its consequence
b. a relationship between two stimulus events
c. a relationship between two response events
d. classical conditioning does not involve learning
c. innate ideas.
d. conditioning.
10. In Watson’s work with Little Albert, why was Albert afraid of the
Santa Claus mask?
a. He had been classically conditioned with the mask.
b. The mask was an unconditioned stimulus creating fear.
c. He generalized his learned fear of the rat.
d. Instrumental conditioning created a fear of strangers.

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Discovering Psychology Viewing Guide 169
11. What was the point of the Skinner box?
a. It kept animals safe.
b. It provided a simple, highly controlled environment.
c. It set up a classical conditioning situation.
d. It allowed psychologists to use computers for research.
12. Skinner found that the rate at which a pigeon pecked at a target
varied directly with
a. the conditioned stimulus.
b. the conditioned response.
c. the operant antecedents.
d. the reinforcing consequences.
13. Imagine a behavior therapist is treating a person who fears going
out into public places. What would the therapist be likely to
focus on?
a. the conditioning experience that created the fear
b. the deeper problems that the fear is a symptom of
c. providing positive consequences for going out
d. reinforcing the patient’s desire to overcome the fear
14. When should the conditioned stimulus be presented in order to
optimally produce classical conditioning?
a. just before the unconditioned stimulus
b. simultaneously with the unconditioned response
c. just after the unconditioned stimulus
d. just after the conditioned response
15. Operant conditioning can be used to achieve all of the following,
except
a. teaching dogs to assist the handicapped.
b. teaching English grammar to infants.
c. teaching self-control to someone who is trying to quit
smoking.
d. increasing productivity among factory workers.
16. Which psychologist has argued that in order to understand and
control behavior, one has to consider both the reinforcements act-
ing on the selected behavior and the reinforcements acting on the
alternatives?
a. E. Thorndike
b. J. Watson
c. B. F. Skinner
d. H. Rachlin
17. If given a choice between an immediate small reinforcer and a
delayed larger reinforcer, an untrained pigeon will
a. select the immediate small one.
b. select the delayed larger one.
c. experiment and alternate across trials.
d. not show any signs of perceiving the difference.
18. In order to produce extinction of a classically conditioned behav-
ior, an experimenter would
a. reward the behavior.
b. pair the behavior with negative reinforcement.
c. present the conditioned stimulus in the absence of the uncon-
ditioned stimulus.
d. model the behavior for the organism.
19. In Pavlov’s early work, bell is to food as
a. unconditioned response is to conditioned response.
b. conditioned stimulus is to unconditioned stimulus.
c. unconditioned response is to conditioned stimulus.
d. conditioned stimulus is to conditioned response.
20. Howard Rachlin has discovered that animals can be taught
self-control through
a. reinforcement.
b. operant conditioning.
c. instrumental conditioning.
d. all of the above.

Memory5
Psychology MattersCore ConceptsKey Questions/Chapter Outline
5.1 What Is Memory?
Metaphors for Memory
Memory’s Three Basic Tasks
Human memory is an information
processing system that works
constructively to encode, store, and
retrieve information.
Would You Want a
“Photographic” Memory?
This ability is rare, and those who
have it say that the images sometimes
interfere with their thinking.
5.2 How Do We Form Memories?
The First Stage: Sensory Memory
The Second Stage: Working Memory
The Third Stage: Long-Term Memory
Each of the three memory stages encodes
and stores memories in a different way,
but they work together to transform
sensory experience into a lasting record
that has a pattern or meaning.
“Flashbulb” Memories: Where
Were You When . . . ?
These especially vivid memories usually
involve emotionally charged events.
Surprisingly, they aren’t always accurate.
Whether memories are implicit or
explicit, successful retrieval depends
on how they were encoded and how
they are cued.
On the Tip of Your Tongue
It is frustrating when you know the
word but can’t quite find it. But you’re
not alone. Most people experience this
about once a week.
CHAPTER PROBLEM How can our knowledge about memory help us
evaluate claims of recovered memories?
CRITICAL THINKING APPLIED The Recovered Memory Controversy
5.3 How Do We Retrieve Memories?
Implicit and Explicit Memory
Retrieval Cues
Other Factors Affecting Retrieval
5.4 Why Does Memory Sometimes
Fail Us?
Transience: Fading Memories Cause
Forgetting
Absent-Mindedness: Lapses of Attention
Cause Forgetting
Blocking: Access Problems
Misattribution: Memories in the Wrong
Context
Suggestibility: External Cues Distort or
Create Memories
Bias: Beliefs, Attitudes, and Opinions
Distort Memories
Persistence: When We Can’t Forget
The Advantages of the “Seven Sins” of
Memory
Improving Your Memory with Mnemonics
Most of our memory problems arise
from memory’s “seven sins”—which
are really by-products of otherwise
adaptive features of human memory.
Using Psychology to Learn
Psychology
In studying psychology, there isn’t
much you need to memorize. Instead,
elaborative rehearsal and distributed
learning will help you learn and
remember concepts.

171
DOES MEMORY MAKE AN ACCURATE AND INDELIBLE RECORD OF OUR PAST? OR IS it like a footprint in the sand, shifting with time and circumstance? In fact, the truth about memory encompasses both of those extremes. Memory can be highly malleable—yet many of our memories are quite accurate. The challenge lies in
knowing when to rely on memory and when to question it, as the following cases will illustrate.
CASE 1 Twelve-year-old Donna began to suffer severe migraine headaches that left her
sleepless and depressed. Concerned, her parents, Judee and Dan, sought help for her. Over
the next year, Donna was passed from one therapist to another, ending up with a psychiatric
social worker who specialized in treatment of child abuse. It was to that therapist that Donna
disclosed—for the first time—having been sexually molested at the age of 3 by a neighbor. The
therapist concluded that memories of the assault, buried in her mind for so long, were probably
responsible for some of Donna’s current problems, so she continued to probe for details and
other possible instances of sexual abuse.
Eventually, the therapist asked her to bring in a family photo album, which included a photo
of Donna, taken at age 2 or 3, wearing only underpants. The therapist suggested this might be
evidence that Donna’s father had a sexual interest in her and, possibly, had molested her. More-
over, the therapist contacted the authorities, who began an investigation (ABC News, 1995).
For two years, Donna felt intense pressure to blame her father, but consistently denied he
had molested her. Finally, amid increasing confusion about her childhood memories, she began
to believe she suffered from “repressed memory syndrome” and that her father had abused her
repeatedly during her childhood. Eventually, Donna was hospitalized. While in the hospital,
she was placed on medication, hypnotized repeatedly, and diagnosed with multiple personality
disorder (now called dissociative identity disorder).

172 C H A P T E R 5 Memory
As for her father, Dan was arrested and tried on charges of abuse based solely on his daugh-
ter’s recovered memory. When his two-week trial ended in a hung jury, Dan went free. Shortly
after the trial, Donna moved to another state with a foster family. In new surroundings and far
away from the system that had supported her story, she began to believe her memories were
false. Eventually, her doctor recommended she be sent back to her family, where they began
the slow process of rebuilding broken relationships and trust.
CASE 2 Ross is a college professor who entered therapy because he was unhappy with his
life. Describing his condition, he said, “I felt somehow adrift, as if some anchor in my life had
been raised. I had doubts about my marriage, my job, everything” (Schacter, 1996, p. 249).
Then, some months after entering therapy, he had a dream that left him with a strong sense of
unease about a certain camp counselor he had known as a youth. Over the next few hours, that
sense of unease gradually became a vivid recollection of the counselor molesting him. From
that point on, Ross became obsessed with the memory, finally hiring a private detective, who
helped him track down the counselor in a small Oregon town. After numerous attempts to talk
with the counselor by telephone, Ross at last made contact and taped the phone conversation.
The counselor admitted molesting Ross, as well as several other boys at the camp. Strangely,
Ross claimed he had simply not thought about the abuse for years—until he entered therapy.
PROBLEM: How can our knowledge about memory help us evaluate claims of
recovered memories?
Keep in mind there is no sure way to “prove a negative.” That is, without some independent
evidence, no one could ever prove conclusively that abuse or some other apparently long-
forgotten event did not occur. Instead, we must weigh claims against our understanding of
memory. In particular, we need answers to the following questions:
• Does memory make an accurate record of everything we experience?
• Are traumatic experiences, such as those of sexual abuse, likely to be repressed (blocked
from consciousness), as Sigmund Freud taught? Or are we more likely to remember our
most emotional experiences, both good and bad?
• How reliable are memories of experiences from early childhood?
• How easily can memories be changed by suggestion, as when a therapist or police officer
might suggest that sexual abuse occurred?
• Are vivid memories more accurate than ordinary, less-distinct memories?
You will find answers to these questions, and many more, in this chapter. Let’s begin with
the most fundamental question of all.
5.1 KEY QUESTION
What Is Memory?
Undoubtedly, memory does play tricks on us. Our best defense against those tricks
is an understanding of how memory works. So let’s begin building that understand-
ing with a definition: Cognitive psychologists view memory as a system that encodes,
stores, and retrieves information—a definition, by the way, that applies equally to
an organism or a computer. Unlike a computer’s memory, however, we humans have
a cognitive memory system that selectively takes information from the senses and
converts it into meaningful patterns that we store and access later as needed. These
memory patterns, then, form the raw material for thought and behavior, which
in turn enables you to recognize a friend’s face, ride a bicycle, recollect a trip to
memory Any system—human, animal, or machine—
that encodes, stores, and retrieves information.

What Is Memory? 173
Disneyland, and (if all goes well) recall the concepts you need during a test. More
generally, our Core Concept characterizes memory this way:
Core Concept 5.1
Human memory is an information processing system that works
constructively to encode, store, and retrieve information.
And how is memory related to learning, the topic of the last chapter? Learning
and memory are different sides of the same coin. You might think of memory as the
cognitive system that processes, encodes, and stores the information we learn, then
later allows us to retrieve it. In other words, memory enables learning. So this chapter
is really an extension of our discussion of cognitive learning in the last section of
Chapter 4. The focus here, however, will be on more complex human learning and
memory, as contrasted with the simpler forms of animal learning and conditioning we
emphasized earlier.
Metaphors for Memory
We often use metaphors to help us understand complicated things. One such
metaphor compares human memory to a library or a storehouse, emphasizing the
ability of memory to hold large amounts of information (Haberlandt, 1999).
Another, compares memory to a computer. Some metaphors for memory, however,
are misleading. That’s certainly the case with the “video recorder” metaphor for
memory, which implies that human memory makes a complete and accurate record
of everything we experience.
Experiments clearly show this video-recorder metaphor is wrong. And, especially
in some cases of “recovered memories,” believing in the unfailing accuracy of mem-
ory can be dangerously wrong. Instead, human memory is an interpretive system that
takes in information and, much like an artist, discards certain details and organizes the
rest into meaningful patterns. As a result, our memories represent our unique percep-
tions of events rather than being accurate or objective representations of the events
themselves.
Simply put, then, we don’t technically retrieve memories—in truth, we reconstruct
them. We start with fragments of memory—like pieces of a jigsaw puzzle. Then, from
these fragments, we reconstruct the incident (or idea, emotion, or image) by filling
in the blanks as we remember it, rather than the way it actually was. Most of the
time this works well enough that you don’t realize just how much of remembrance is
actually reconstruction.
A look at Figure 5.1 should convince you of this reconstructive process. Which
image is the most accurate portrayal of a penny? Unless you are a coin collector, you
probably pay little attention to the details of these familiar objects. So, when retrieving
the image of a penny, you automatically fill in the gaps and missing details—without
realizing how much of the memory image you are actually creating.
Some memories are sketchier than others. In general, psychologists have found we
make the most complete and accurate memory records for:
• Information on which we have focused our attention, such as a friend’s words
against a background of other conversations
• Information in which we are interested, such as the plot of a favorite movie
• Information that arouses us emotionally, such as an especially enjoyable or painful
experience (unless the material also brings our biases into play, as when we are in
a heated discussion with a loved one)
• Information that connects with previous experience, such as a news item about the
musician whose concert you attended last week
• Information that we rehearse, such as material reviewed before an exam
C O N N E C T I O N CHAPTER 1
Cognitive psychology is one of
the six main perspectives in
psychology (p. 16).
The cognitive perspective says that
our cognitions can affect our mental
health—or our mental disorders.

174 C H A P T E R 5 Memory
The rest of the chapter will unfold this cognitive approach to memory, known as
the information-processing model. It emphasizes the systematic changes information un-
dergoes on its way to becoming a permanent memory—quite different from the naïve
video recorder model. The information-processing model also emphasizes that mem-
ory is functional—that is, it performs useful functions for us. The most basic of these,
we will see below, are the encoding, storage, and retrieval of information.
Memory’s Three Basic Tasks
In simplest terms, human memory takes essentially meaningless sensory information
(such as the sounds of your professor’s voice) and changes it into meaningful patterns
(words, sentences, and concepts) you can store and use later. To do so, memory must
first encode the incoming sensory information in a useful format.
Encoding first requires that you select some stimulus event from the vast array of
inputs assaulting your senses and make a preliminary classification of that stimulus. Is it a
sound, visual image, odor, taste, or pain? Next you identify the distinctive features of that
input. If it’s a sound, is it loud, soft, or harsh? Does it fit some pattern, such as a car horn,
a melody, a voice? Is it a sound you have heard before? Finally, you mentally tag, or label,
an experience to make it meaningful. (“It’s Dr. Johnson. He’s my psychology professor!”)
Often, encoding is so automatic and rapid that we have no awareness of the
process. For example, you can probably recall what you had for breakfast this morning,
even though you didn’t deliberately try to make the experience “stick” in your mind.
Emotionally charged experiences, such as an angry exchange with a colleague, are even
more likely to lodge in memory without any effort to encode them (Dolan, 2002).
On the other hand, memories for concepts, such as the basic principles of psychol-
ogy, usually require a deliberate encoding effort to establish a usable memory. In a
process called elaboration, you attempt to connect a new concept with existing infor-
mation in memory. One way to do this is to link the new material to personal, concrete
examples, as when you associated the term negative reinforcement with the removal of
pain when you take an aspirin. (As an aid to elaboration, this text deliberately provides
many such examples that, we hope, will help you connect new concepts with your own
experiences.) In fact, failure to elaborate is a common cause of memory errors: If you
didn’t know the answer to the Penny Test, for example, you probably never paid close
attention to the configuration of a penny, and thus never really encoded it to begin
with. (The correct answer, by the way, is A.)
information-processing model A cognitive
understanding of memory, emphasizing how infor-
mation is changed when it is encoded, stored, and
retrieved.
encoding The first of the three basic tasks of
memory, involving the modification of information to
fit the preferred format for the memory system.
FIGURE 5.1
The Penny Test
Which of these images is an accurate
portrayal of a penny?
Source: Nickerson, R., & Adams, M. (1979).
Long-term memory for a common object. Cognitive
Psychology, 11(1), 287–307. Copyright © 1979.
Reprinted by permission of Elsevier.
A B C D E
K L M N O
F G H I J

What Is Memory? 175
Storage, the second essential memory task, involves the retention of encoded
material over time. But it’s not a simple process. As we get deeper into the workings of
memory, you will learn that memory consists of three parts, or stages, each of which
stores memories for different lengths of time and in different forms. The trick of get-
ting difficult-to-remember material into long-term storage, then, is to recode the in-
formation in the way long-term memory “likes” it before the time clock runs out. For
example, while listening to a lecture, you may have just a few seconds to encode a
pattern or meaning in the sound of your professor’s voice before new information
comes along and the old information is lost.
Retrieval, the third basic memory task, is the payoff for your earlier efforts in
encoding and storage. When you have a properly encoded memory, it takes only a split
second for a good cue to access the information, bring it to consciousness, or, in some
cases, to influence your behavior at an unconscious level. (Let’s test the ability of your
conscious retrieval machinery: Can you remember which of the three memory tasks
occurs just before storage?)
Alas, retrieval doesn’t always go well, because the human memory system—marvelous
as it is—sometimes makes errors, distorts information, or even fails us completely. In
the last section of the chapter, we will take a close look at these problems, which memory
expert Daniel Schacter (1996) calls the “seven sins of memory.”1 The good news is you
can combat memory’s “sins” with a few simple techniques that you will also learn about
in the following pages.
PSYCHOLOGY MATTERS
Would You Want a “Photographic” Memory?
Suppose your memory were so vivid and accurate you could “read” paragraphs of
this book from memory during your next exam. Such was the power of a 23-year-old
woman tested by Charles Stromeyer and Joseph Psotka (1970). One of the amazing
things she could do was to look at the meaningless configuration of dots in the left-
hand pattern in the Do It Yourself! box and combine it mentally with the right-hand
image. The result was the combined pattern shown in Figure 5.2. (Did you see the
number “63” before you looked at the solution?) Wouldn’t it be great to have such a
“photographic” memory? Not entirely, it turns out.
The technical term for “photographic memory” is eidetic imagery. Psychologists
prefer this term because eidetic images differ in many important respects from im-
ages made by a camera (Haber, 1969, 1980; Searleman, 2007). For example, a pho-
tographic image renders everything in minute detail, while an eidetic image portrays
the most interesting and meaningful parts of the scene most accurately and is subject
to the same kind of distortions found in “normal” memories.
Eidetic memories also differ in several respects from typical human memory
images. For one thing, eidetikers describe their memory images as having the viv-
idness of the original experience (Neisser, 1967). For another, eidetic images are
visualized as being “outside the head” rather than inside—in the “mind’s eye.” (Yet,
unlike a person who is hallucinating, eidetikers recognize these images as mental
images.) Further, an eidetic image can last for several minutes—even for days, in
some cases. For example, the woman tested by Stromeyer and Psotka could pass
the dot-combining test even when she saw the two patterns 24 hours apart. But,
remarkable as this is, the persistence of eidetic images can be a curse. Eidetikers
report that their vivid imagery sometimes clutters their minds and interferes with
other things they want to think about (Hunter, 1964).
storage The second of the three basic tasks of
memory, involving the retention of encoded material
over time.
retrieval The third basic task of memory, involving
the location and recovery of information from memory.
eidetic imagery An especially clear and per-
sistent form of memory that is quite rare; sometimes
known as “photographic memory.”
1 Schacter’s “seven sins” of memory are a pun on the famous seven sins of medieval times. You can remember them
by the acronym WASPLEG, which refers to Wrath, Avarice, Sloth, Pride, Lust, Envy, and Gluttony.

176 C H A P T E R 5 Memory
Eidetic imagery appears most commonly in children and only rarely in adults.
One estimate suggests that up to five percent of children show some eidetic
ability—although in most instances it’s not good enough to pass the dot-combining
test (Gray & Gummerman, 1975). And, in case you were wondering, there are no
gender differences in eidetic memory: Boys and girls alike seem to have similar
likelihoods of possessing the ability (Searleman, 2007). While no one knows why
eidetic imagery tends to disappear in adults, it may follow some sort of develop-
mental sequence—like losing one’s baby teeth. Possibly its disappearance is related
to the emphasis placed on logical thought that typically comes with the beginning
of formal education, and dovetails with a change in children’s thinking styles.
Case studies also suggest a connection between the decline of eidetic imagery
and the development of language skills: Eidetikers report that eidetic images are
strongest when they remain mere images; describing an eidetic image in words
makes it fade from memory, and eidetikers learn to exploit this fact to control
their intrusive imagery (Haber, 1969, 1970). Research in forensic psychology has
found that, for ordinary people (noneidetikers) as well, giving verbal descriptions
of suspects’ faces interferes with later memories for those faces. Likewise, trying
to describe other hard-to-verbalize perceptions, such as a voice or the taste of a
wine, impairs most people’s abilities to recall those perceptions later (Bower, 2003;
Dodson et al., 1997).
A study from Nigeria further supports the idea that loss of eidetic ability may result
from conflict between language skills and visual imagery: Eidetic imagery was found to
be common not only among Ibo children but also among illiterate adults of the tribe
who were living in rural villages. Although many of these adults could correctly draw
details of images seen earlier, members of the same tribe who had moved to the city
and learned to read showed little eidetic ability (Doob, 1964).
Whatever eidetic memory may be, it is clearly rare—so rare, in fact, that some
psychologists have questioned its existence (Crowder, 1992). The few existing studies
of “photographic memory” have portrayed it as different from everyday memory, as
we have seen. Truthfully, however, we know relatively little about the phenomenon,
and few psychologists are currently studying it.
Eidetic imagery presents not only a practical problem for those rare individuals
who possess it but also a theoretical problem for cognitive psychologists. If eidetic
imagery exists, is a known component of memory responsible? On the other hand, if it
proves to be a unique form of memory, how does it fit with the widely accepted three-
stage model of memory—which we will discuss next?
C O N N E C T I O N CHAPTER 7
In Piaget’s theory, the concrete
operational stage, typically
beginning around age 6 to 7,
marks the transition from
magical thinking to logical
thinking (p. 285).
A TEST OF EIDETIC IMAGERY
Look at the dot pattern on the left in the
figure for a few moments and try to fix it
in your memory. With that image in mind,
look at the dot pattern on the right. Try
to put the two sets of dots together by
recalling the first pattern while looking
at the second one. If you are the rare
individual who can mentally combine the
two patterns, you will see something not
apparent in either image alone. Difficult?
No problem if you have eidetic imagery—
but impossible for the rest of us. If you
want to see the combined images, but
can’t combine them in your memory, look
at Figure 5.2.
A Test of Eidetic Imagery
People with good eidetic imagery can mentally combine these two images to see some-
thing that appears in neither one alone.

How Do We Form Memories? 177
5.2 KEY QUESTION
How Do We Form Memories?
If information in a lecture is to become part of your permanent memory, it must be
processed in three sequential stages: first in sensory memory, then in working mem-
ory, and finally in long-term memory. The three stages work like an assembly line to
convert a flow of incoming stimuli into meaningful patterns you can store and later
reconstruct. This three-stage model, originally developed by Richard Atkinson and
Richard Shiffrin (1968), is now widely accepted—with some elaborations and modi-
fications. Figure 5.3 shows how information flows through the three stages. (Caution:
Don’t get these three stages confused with the three basic tasks of memory we covered
earlier.)
Sensory memory, the most fleeting of the three stages, typically holds sights, sounds,
smells, textures, and other sensory impressions for a maximum of a few seconds.
Although sensory memory usually operates on an unconscious level, you can see its
effects in the fading luminous trail made by a moving flashlight or a twirling Fourth-
of-July sparkler. You can also hear the effects of fading sensory memories in the blend-
ing of one note into another as you listen to a melody. In general, these short-lived
images allow us to maintain incoming sensory information just long enough for it to
be screened for importance by working memory.
Working memory, the second stage of processing, selectively takes information from
the sensory registers and makes connections with items already in long-term storage.
(It is this connection we mean when we say, “That rings a bell!”) Working memory
holds information for up to 20 to 30 seconds (Nairne, 2003), making it a useful buf-
fer for temporarily holding a name you have just heard or following directions some-
one has just given you. Originally, psychologists called this stage short-term memory
(STM), reflecting the notion that this was merely a short-term, passive storage bin.
Research has discovered, however, there are multiple active mental processes working
at lightning speed to process information in this stage—hence the newer term working
memory.
Long-term memory (LTM), the final stage of processing, receives information from work-
ing memory and can store it for long periods—sometimes for a lifetime. Information in
sensory memory The first of three memory
stages, preserving brief sensory impressions of stimuli.
working memory The second of three memory
stages, and the one most limited in capacity. It
preserves recently perceived events or experiences
for less than a minute without rehearsal.
long-term memory (LTM) The third of three
memory stages, with the largest capacity and longest
duration; LTM stores material organized according to
meaning.
FIGURE 5.3
The Three Stages of Memory
(simplified)
Memory is generally thought to be divided
into three stages of processing. Every-
thing that eventually goes into long-term
storage must first be processed by
sensory memory and working memory.
Sensory
memory Long-term memory
Working
memory
FIGURE 5.2
What an Eidetiker Sees
The combined images from the Do It
Yourself! box form a number pattern.
Source: Klatzky, R. (1980). Human Memory:
Structures and Processes. San Francisco:
W. H. Freeman and Company. Copyright © 1975,
1980 by W. H. Freeman and Company. Used with
permission.
Check Your Understanding
1. ANALYSIS: What is a major objection to the “video recorder”
model of human memory?
2. RECALL: What are the three essential tasks of memory?
3. ANALYSIS: Suppose you have just adopted a new cat. You note
her unique markings so you can recognize her among other cats
in the neighborhood. What would a cognitive psychologist call this
process of identifying the distinctive features of your cat?
4. UNDERSTANDING THE CORE CONCEPT: Which of the
following memory systems reconstructs material during retrieval?
a. computer memory
b. human memory
c. video recorder memory
d. information recorded in a book
Answers 1. Unlike a video recorder, which makes an accurate and detailed record, memory stores an interpretation of experience. 2. Encoding,
storage, and retrieval 3. Encoding 4. b
Study and Review at MyPsychLab

178 C H A P T E R 5 Memory
long-term memory includes all our knowledge about the world, from an image of your
mother’s face to the lyrics to your favorite song and the year that Wilhelm Wundt estab-
lished the first psychology laboratory. (Do you remember the year from Chapter 1?)
Our Core Concept captures the three stages in brief:
Core Concept 5.2
Each of the three memory stages encodes and stores memories in a
different way, but they work together to transform sensory experience
into a lasting record that has a pattern or meaning.
Our focus in this section will be on the unique contributions each stage makes to
the final memory product (see Table 5.1). More specifically, we will look at each stage
in terms of its storage capacity, its duration (how long it retains information), its struc-
ture and function, and its biological basis.
The First Stage: Sensory Memory
Your senses take in far more information than you can possibly use. While reading
this book, they serve up all the words on the page, sounds in the room, the feel of your
clothes on your skin, the temperature of the air, the slightly hungry feeling in your
stomach. . . . How does the brain deal with this multitude of sensory input?
It’s the job of sensory memory to hold the barrage of incoming sensation just long
enough for your brain to scan it and decide which stream of information needs atten-
tion. But just how much information can sensory memory hold? Cognitive psycholo-
gist George Sperling answered this question by devising one of psychology’s simplest
and most clever experiments.
TABLE 5.1 The Three Stages of Memory Compared
Sensory Memory Working Memory Long-Term Memory
Function Briefly holds information
awaiting entry into
working memory
Involved in control of
attention
Attaches meaning to
stimulation
Makes associations
among ideas and
events
Long-term storage of
information
Encoding Sensory images: no
meaningful encoding
Encodes information
(especially by meaning)
to make it acceptable
for long-term storage
Stores information in
meaningful mental
categories
Storage capacity 12–16 items 7 ± 2 chunks Unlimited
Duration From 1/4 second to a few
seconds
About 20 seconds
unless repeatedly
rehearsed
Unlimited
Structure A separate sensory
register for each sense
Central executive
Phonological loop
Sketchpad
Episodic buffer
Procedural memory
and declarative
memory (further
subdivided into
semantic and episodic
memory)
Biological basis Sensory pathways Involves the
hippocampus and
frontal lobes
Involves various parts
of the cerebral cortex
Like the trail of light from these spar-
klers, sensory memory holds incoming
sensory information for just a brief
moment.

How Do We Form Memories? 179
The Capacity and Duration of Sensory Memory Sperling demonstrated that sen-
sory memory can hold far more information than ever reaches consciousness. He first
asked people to remember, as best they could, an array of letters flashed on a screen
for a fraction of a second. (You might try glancing briefly at the array below and then
trying to recall as many as you can.)
D J B W
X H G N
C L Y K
Not surprisingly, most people could remember only three or four items from a
fraction-of-a-second exposure.
But, Sperling wondered, could it be possible that far more information than these
three or four items entered a temporary memory buffer but vanished before it could be
reported? To test this conjecture, he modified the experimental task as follows. Imme-
diately after the array of letters flashed on the screen, an auditory cue signaled which
row of letters to report: A high-pitched tone indicated the top row, a medium tone the
middle row, and a low tone meant the bottom row. Thus, immediately after seeing the
brief image and hearing a beep, respondents were to report items from only one row,
rather than items from the whole array.
Under this partial report condition, most people achieved almost perfect accuracy—
no matter which row was signaled. That is, Sperling’s volunteers could accurately re-
port any single row, but not all rows. This result suggested that the actual storage
capacity of sensory memory can be 12 or more items—even though all but three or
four items usually disappear from sensory memory before they can enter consciousness
(Sperling, 1960, 1963).
Would it be better if our sensory memories lasted longer so we would have more
time to scan them? Probably not. With new information constantly flowing in, old in-
formation needs to disappear quickly, lest the system become overloaded. We are built
so that sensory memories last just long enough to dissolve into one another and give us
a sense of flow and continuity in our experience. Fortunately, they do not usually last
long enough to interfere with new sensory impressions.
The Structure and Function of Sensory Memory You might think of sensory
memory as a sort of mental movie screen, where images are projected fleetingly
and then disappear. In fact, this blending of images in sensory memory gives us the
impression of motion in a “motion picture”—which is really just a rapid series of still
images.
But not all sensory memory consists of visual images. We have a separate sensory
register for each sense, with each register holding a different kind of sensory informa-
tion, as shown in Figure 5.4. The register for vision, called iconic memory, stores the
encoded light patterns experienced as visual images. Similarly, the sensory memory for
hearing, known as echoic memory, holds encoded auditory stimuli.
FIGURE 5.4
Multiple Sensory Stores
We have a separate sensory memory for
each of our sensory pathways. All feed
into working memory.
Visual stimulation
Auditory stimulation
Tactile stimulation
(touch)
Olfactory stimulation
(smell)
Gustatory stimulation
(taste)
Iconic memory
Echoic memory
Working
memory
Long-term
memory
Tactile sensory memory
Olfactory sensory memory
Gustatory sensory memory

180 C H A P T E R 5 Memory
Please note that images in sensory memory have no meaning attached to them—
just as digital images have no meaning to a camera. It’s the job of sensory memory
simply to store the images briefly. It’s in the next stage, working memory, where we
add meaning to sensation.
The Biological Basis of Sensory Memory The biology of sensory memory appears
to be relatively simple. In this initial stage, memory images take the form of neural
activity in the sense organs and their pathways to the brain. Thus, sensory memory
consists of the rapidly fading trace of stimulation in our sensory systems (Bower,
2000b; Glanz, 1998). Working memory then “reads” these fading sensory traces and
decides which ones will gain admittance into the spotlight of attention and which will
be ignored and disappear.
The Second Stage: Working Memory
In the second stage of processing, working memory serves as the temporary storage
site for a new name you just heard or for the first part of this sentence while you read
the remainder. More broadly, working memory is the processor of conscious expe-
rience, including information coming from sensory memory, as well as information
being retrieved from long-term memory (Jonides et al., 2005). Everything entering
consciousness does so through working memory.
Moreover, working memory provides a mental “work space” where we sort and
encode information before adding it to more permanent storage (Shiffrin, 1993). In
doing so, it makes experiences meaningful by blending them with information from
long-term memory. To give a concrete example: Working memory is the register into
which you retrieve the information you learned in yesterday’s class as you review for
tomorrow’s test.
You might think of working memory, then, as the “central processing chip” for
the entire memory system. In this role, it typically holds information for 20–30
seconds—far longer than sensory memory. If you make a special effort to rehearse
the material, information can remain active even longer, as when you repeat a new
phone number to yourself before putting it into your phone’s contact list. It is also
the mental work space in which we consciously mull over ideas and images pulled
from long-term storage in the process we call thinking. In all these roles, then, working
memory is not only the center of mental action but also the liaison among other
components of memory.
The Capacity and Duration of Working Memory Psychologist George Miller
(1956) famously suggested that the “magic number” of this second stage of mem-
ory was 7±2. What he meant was that the storage component of working memory
holds about seven items—a fact that caused lots of distress when phone companies
began requiring callers to add an area code to the old seven-digit phone number.
Working memory’s storage capacity does vary slightly from person to person, so
you may want to assess how much yours can hold by trying the test in the Do It
Yourself! box.
When we overload working memory, earlier items usually drop away to accommo-
date more recent ones. Yet, when working memory fills up with information demand-
ing attention, we can fail to notice new information streaming into our senses. That’s
why, in the opinion of many experts, this limited capacity of working memory makes it
unsafe to use your cell phone while driving (Wickelgren, 2001). In fact, research finds
we only process about 50 percent of incoming sensory information when we are con-
currently driving and talking on a cell phone—even when the driver is using a hands-
free set. And one in four auto accidents result from driving while using a cell phone
(National Safety Council, 2010).

How Do We Form Memories? 181
Note that working memory’s meager storage capacity is
significantly smaller than that of sensory memory. In fact, working
memory has the smallest capacity of the three memory stages. This
constraint, combined with its limited duration, makes working
memory the information “bottleneck” of the memory system (see
Figure 5.5). These twin problems of limited capacity and short
duration present special obstacles for students trying to pro-
cess and remember large amounts of information from a lecture
or textbook. Fortunately, there are ways to work around these
difficulties, as we will see.
Chunks and Chunking In memory, a chunk is any pattern or meaningful unit of informa-
tion. It might be a single letter or number, a name, or even a concept. For example, the let-
ters P-H-I-L could constitute four chunks. However, you probably recognize this sequence
as a name (in fact, the name of one of your authors), so you can combine the four letters
into a single chunk. Thus, chunking helps you get more material into the seven slots of
working memory.
The phone companies capitalized on chunking years ago. When they originally
grouped the seven digits of a phone number (e.g., 6735201) into two shorter strings of
numbers (673-5201), they helped us collapse seven separate items into two chunks—
and now, with the addition of the area code conveniently chunked as well, we have
only one additional thing to remember. The government uses the same chunking prin-
ciple to help us remember our nine-digit Social Security numbers.
The Role of Rehearsal Imagine you are ordering pizza, and you ask your room-
mates what toppings they want. To keep their list in your working memory while
you call the pizza place, you might repeat it to yourself over and over. This tech-
nique is called maintenance rehearsal, and it serves us well for maintaining informa-
tion temporarily in consciousness by preventing competing inputs from crowding
it out. But repetition is not an efficient way to transfer information to long-term
memory, even though people often attempt to do so. So using this strategy to try to
learn material for a test won’t work very well.
A better strategy is elaborative rehearsal. With this method, information is not
merely repeated but is actively connected to knowledge already stored. One way to
do this is to associate a new idea with something it logically brings to mind for you.
When you read about echoic memory, for example, did you think “that makes sense,
since echoes have to do with sound?” Another way is to think of personal examples
of concepts. In the last chapter, perhaps you came up with examples of positive rein-
forcement, negative reinforcement, and classical conditioning from your own life; if
you did, we’ll bet those concepts were easier to remember when you were tested on
them.
chunking Organizing pieces of information into
a smaller number of meaningful units (or chunks)—a
process that frees up space in working memory.
maintenance rehearsal A working-memory
process in which information is merely repeated or re-
viewed to keep it from fading while in working memory.
Maintenance rehearsal involves no active elaboration.
elaborative rehearsal A working-memory
process in which information is consciously reviewed
and actively related to information already in LTM.
FINDING YOUR WORKING MEMORY CAPACITY
Look at the following list of numbers and
scan the four-digit number, the first number
on the list. Don’t try to memorize it. Just read
it quickly; then look away from the page and
try to recall the number. If you remember it
correctly, go on to the next longer number,
continuing down the list until you begin to
make mistakes. How many digits are in the
longest number that you can squeeze into
your working memory?
7 4 8 5
3 6 2 1 8
4 7 9 1 0 3
2 3 8 4 9 7 1
3 6 8 9 1 7 5 6
7 4 7 2 1 0 3 2 4
8 2 3 0 1 3 8 4 7 6
The result is your digit span, or your
working (short-term) memory capacity for
digits. Studies show that, under ideal test-
ing conditions, most people can remember
five to nine digits. If you remembered
more, you may have been using special
“chunking” techniques.
FIGURE 5.5
The Working Memory Bottleneck
Caught in the middle, with a much
smaller capacity than sensory and long-
term memories, working memory becomes
an information bottleneck in the
memory system. As a result, much
incoming information from sensory
memory is lost.
Sensory
memory
Long-term
memory
Working memory
5 to 9 ”chunks”

182 C H A P T E R 5 Memory
One caution about elaborative rehearsal: Make sure you have your facts straight
before creating a web of connections for them! If, for example, you erroneously believe
that memory is like a video recorder and think for a moment about how that makes
sense, you are reinforcing a false memory. Likewise, if the therapist treating Donna (at
the beginning of this chapter) told her to imagine situations where her Dad may have
had opportunities to molest her, merely imagining those events could help create false
memories (Loftus, 1997a; Zaragoza et al., 2011).
The Structure and Function of Working Memory When we introduced you to the
concept of working memory at the beginning of this section, we said its name reflected
the active nature of this stage of the memory process. So what are the activities work-
ing memory engages in? Currently, researchers Allen Baddeley and his colleagues be-
lieve there are four: the central executive, the phonological loop, the sketchpad, and an
episodic buffer (Baddeley, 2000; Baddeley & Hitch, 1974). Let’s take a closer look at
each one (see Figure 5.6).
The Central Executive The information clearinghouse for working memory, the central
executive, directs your attention to important input from both sensory memory and
long-term memory and interfaces with the brain’s voluntary (conscious) response sys-
tem. Even now, as you sit reading this text, the central executive in your working mem-
ory is helping you decide whether to attend to these words or to other stimuli flowing
in from your other senses, along with thoughts from long-term memory.
Acoustic Encoding: The Phonological Loop When you read words like “whirr,” “pop,”
“cuckoo,” and “splash,” you can hear in your mind the sounds they describe. This acoustic
encoding also happens with words that don’t have imitative sounds. That is, working
memory converts all the words we encounter into the sounds of our spoken language and
shuttles them into its phonological loop—whether the words come through our eyes, as
acoustic encoding The conversion of informa-
tion, especially semantic information, to sound
patterns in working memory.
FIGURE 5.6
A Model of Working Memory
Atkinson and Shiffrin’s original model divided memory into three stages. Events must first be processed by sensory memory and short-term mem-
ory (now called working memory) before they finally go into long-term memory storage—from which they can later be retrieved back into working
memory. Baddeley’s (2003) updated version of working memory includes a central executive that directs attention, a sketchpad for visual and
spatial information, a phonological loop for sounds, and an episodic buffer that can combine many kinds of information into memories of events.
This drawing includes all of these refinements to the original model of working memory.
Source: Baddeley, A. (2000). The episodic buffer: A new component of working memory? Trends in Cognitive Sciences, 4, 417–423.
Working Memory
Long-Term Memory
Central
Executive
Sensory
Memory
Episodic Buffer
(events)
Visual LTM
for words
Sketchpad
(visual image)
Episodic
LTM
LTM for sounds
(e.g. of language)
Stimulation Behavior
Phonological
Loop
(sounds)

How Do We Form Memories? 183
in reading, or our ears, as in listening to speech (Baddeley, 2001). There, working memory
maintains the verbal patterns in an acoustic (sound) form as they are processed.
Acoustic encoding can create its own brand of memory errors. When people recall lists
of letters they have just seen, their mistakes often involve confusions of letters that have
similar sounds—such as D and T—rather than letters with a similar appearance—such as
E and F (Conrad, 1964). Mistakes aside, however, acoustic encoding has its advantages,
particularly in learning and using language (Baddeley et al., 1998; Schacter, 1999).
Visual and Spatial Encoding: The Sketchpad Serving much the same function for visual
and spatial information, working memory’s sketchpad encodes visual images and men-
tal representations of objects in space. It holds the visual images you mentally rummage
through when you’re trying to remember where you left your car keys. It also holds the
mental map you follow from home to class. Neurological evidence suggests that the
sketchpad requires coordination among several brain systems, including the frontal and
occipital lobes.
Binding Information Together: The Episodic Buffer The most recent addition to Baddeley’s
model of working memory, the episodic buffer appears to bind the various pieces of
information in working memory into a coherent episode. When planning a series of er-
rands, for instance, we have to first identify all the places we need to go, then organize
them into a logical route based on location, and finally calculate about how long the
entire trip will take. So we have all the locations swimming around in our working
memory as we mentally map them out, and various amounts of time associated with
each one as we consider what we need to accomplish at each place. The episodic buffer
acts as the temporary storage facility for these various pieces of our puzzle as we work
it out. It also enables us to remember story lines of movies and other events, as it pro-
vides a place to organize the visual, spatial, phonological, and chronological aspects
into a single memorable episode (Baddeley, 2003).
Levels of Processing in Working Memory Here’s an important tip: The more
connections you can make in working memory between new information and
knowledge you already have, the more likely you are to remember it later. Obviously
this requires interaction between working memory and long-term memory. According
to the levels-of-processing theory proposed by Fergus Craik and Robert Lockhart
(1972), “deeper” processing—establishing more connections with long-term
memories—makes new information more meaningful and more memorable.
A famous experiment will illustrate this point.
Craik and Tulving (1975) had volunteers examine a list of 60 common
words presented on a screen one at a time. As each word appeared, experi-
menters asked questions designed to influence how deeply each word was
processed. For example, when BEAR appeared on the screen, the experiment-
ers would ask one of three questions: “Is it in capital letters?” “Does it rhyme
with chair?” “Is it an animal?” Craik and Tulving theorized that merely think-
ing about capital letters would not require processing the word as deeply as
would comparing its sound with that of another word. But the deepest level
of processing, they predicted, would occur when some aspect of the word’s
meaning was analyzed, as when they asked whether BEAR was an animal.
Thus, they predicted that items processed more deeply would leave more ro-
bust traces in memory. And, sure enough, when participants were later asked
to pick the original 60 words out of a larger list of 180, they remembered the
deeply processed words the best, as the graph in Figure 5.7 shows. You can
apply this strategy to your studying: Deeper processing of new information
will help you develop stronger memories of the material.
The Biological Basis of Working Memory Although some details remain
unclear, working memory probably holds information in the form of messages
flashed repeatedly in nerve circuits. Brain imaging implicates brain regions in
levels-of-processing theory The explanation
for the fact that information that is more thoroughly
connected to meaningful items in long-term memory
(more “deeply” processed) will be remembered better.
FIGURE 5.7
Results of Levels-of-Processing Experiment
In the Craik and Tulving (1975) experiment, words
that were processed more deeply (for meaning) were
remembered better than words examined for rhymes
or for target letters.
100%
80%
60%
40%
20%
letters
Co
rr
ec
t
Re
sp
on
se
s
Levels of Processing
rhymes meaning

184 C H A P T E R 5 Memory
the frontal cortex (Beardsley, 1997b; Smith, 2000), which in turn project to all sensory
parts of the brain and areas known to be involved in long-term storage. Brain imaging
also suggests the frontal lobes house some anatomically distinct “executive processes”
that focus attention on information in short-term storage (Smith & Jonides, 1999).
Together, these brain modules direct attention, set priorities, make plans, update the
contents of working memory, and monitor the time sequence of events.
The Third Stage: Long-Term Memory
Can you remember who discovered classical conditioning? Can you ride a bicycle?
How many birthdays have you had? Such information, along with everything else you
know, is stored in your long-term memory (LTM), the last of the three memory stages.
Given the vast amount of data stored in LTM, it is a marvel that we can so easily
gain access to so much of it. Remarkably, if someone asks your name, you don’t have
to rummage through a lifetime of information to find the answer. The method behind
the marvel involves a special feature of long-term memory: Words and concepts are en-
coded by their meanings. This connects them, in turn, with other items that have simi-
lar meanings. Accordingly, you might picture LTM as a huge web of interconnected
associations. As a result, good retrieval cues (stimuli that prompt the activation of a
long-term memory) can navigate though the web and help you quickly locate the item
you want amid all the data stored there.
The Capacity and Duration of Long-Term Memory How much information can
long-term memory hold? As far as we know, it has unlimited storage capacity. (No
one has yet maxed it out, so you don’t have to conserve memory by cutting back on
your studying.) LTM can store the information of a lifetime: all the experiences, events,
information, emotions, skills, words, categories, rules, and judgments that have been
transferred from working memory. Thus, your LTM contains your total knowledge
of the world and of yourself. This makes long-term memory the clear champion in
both duration and storage capacity among the three stages of memory. But how does
LTM manage to have unlimited capacity? That’s another unsolved mystery of memory.
Perhaps we might conceive of LTM as a sort of mental “scaffold,” so the more associa-
tions you make, the more information it can hold.
The Structure and Function of Long-Term Memory With a broad overview of
LTM in mind, let’s look at some of the details of its two main components. One, a
register for the things we know how to do, is called procedural memory. The other,
which stores information we can describe—facts we know and experiences we
remember—is called declarative memory. We know that procedural and declarative
memory are distinct because brain-damaged patients may lose one but not the other
(as we will see).
Procedural Memory We call on procedural memory when riding a bicycle, tying shoe-
laces, or playing a musical instrument. Indeed, we use procedural memory to store the
mental directions, or “procedures,” for all our well-practiced skills (Schacter, 1996).
Much of procedural memory operates outside of awareness: Only during the early
phases of training, when we must concentrate on every move we make, must we think
consciously about the details of our performance. Later, after the skill is thoroughly
learned, it operates largely beyond the fringes of awareness, as when a concert pia-
nist performs a piece without consciously recalling the individual notes. (Figure 5.8
should help you clarify the relationship between the two major components of long-
term memory.)
Declarative Memory We use declarative memory to store facts, impressions, and events.
Recalling the major perspectives in psychology or your most memorable vacation de-
pends on declarative memory. In contrast with procedural memory, using declarative
procedural memory A division of LTM that
stores memories for how things are done.
declarative memory A division of LTM that
stores explicit information; also known as fact memory.
Declarative memory has two subdivisions, episodic
memory and semantic memory.
Procedural memory allows experts like
Oregon quarterback Darron Thomas to per-
form complex tasks automatically, without
consciously recalling all the details.

How Do We Form Memories? 185
Semantic memory
Includes memory for:
language
facts
general knowledge
concepts
Episodic memory
Declarative memory
(knowing what)
Long-term memory
Procedural memory
(knowing how)
Includes memory for:
events
personal experiences
Includes memory for:
motor skills
operant conditioning
classical conditioning
FIGURE 5.8
Components of Long-Term Memory
Declarative memory involves knowing
specific information—knowing “what.”
It stores facts, personal experiences,
language, concepts—things about which
we might say, “I remember!” Procedural
memory involves knowing “how”—
particularly motor skills and behavioral
learning.
memory typically requires conscious mental effort, as you see when people roll their
eyes or make facial gestures while trying to recall facts or experiences.
To complicate matters, declarative memory itself has two major subdivisions,
episodic memory and semantic memory. One deals with the rich detail of personal
experiences (your first kiss), while the other simply stores information, without an
“I-remember-when” context—information like the multiplication tables or the capital
of your state.
Episodic memory stores your memories of events, or “episodes,” in your life. It
also stores temporal coding (or time tags) to identify when the event occurred and
context coding that indicates where it took place. For example, you store memories
of your recent vacation or of an unhappy love affair in episodic memory, along with
codes for where and when these episodes occurred. In this way, episodic memory
acts as your internal diary or autobiographical memory. You consult it when some-
one says, “Where were you on New Year’s Eve?” or “What did you do in class last
Tuesday?”
Semantic memory is the other division of declarative memory. (Refer to Figure 5.8 if
this is becoming confusing.) It stores the basic meanings of words and concepts. Usu-
ally, semantic memory retains no information about the time and place in which its
contents were acquired. Thus, you keep the meaning of cat in semantic memory—but
probably not a recollection of the occasion on which you first learned the meaning
of cat. In this respect, semantic memory more closely resembles an encyclopedia or a
database than an autobiography. It stores a vast quantity of facts about names, faces,
grammar, history, music, manners, scientific principles, and religious beliefs. All the
facts and concepts you know are stored there, and you consult its registry when some-
one asks you, “Who was the third president?” or “What are the two major divisions of
declarative memory?”
Schemas When you attend a class, have dinner at a restaurant, make a phone call, or
go to a birthday party, you know what to expect, because each of these events involves
familiar scenarios. Cognitive psychologists call them schemas: clusters of knowledge in
semantic memory that give us a context for understanding events (Squire, 2007). The
exact contents of our schemas depend, of course, on culture and personal experience,
but the point is that we invoke schemas to make new experiences meaningful.
episodic memory A subdivision of declarative
memory that stores personal events or “episodes.”
semantic memory A subdivision of declarative
memory that stores general knowledge, including the
meanings of words and concepts.
schema Cluster of related information that repre-
sents ideas or concepts in semantic memory. Schemas
provide a context for understanding objects and events.
On the TV show Are You Smarter Than a
5th Grader?, host Jeff Foxworthy’s
questions call for facts stored in semantic
memory.

186 C H A P T E R 5 Memory
Schemas allow us quick access to information. So if someone says “birthday party,”
you can immediately draw on information that tells you what you might expect to be
associated with a birthday party, such as eating cake and ice cream, singing “Happy
Birthday,” and opening presents. Just as important, when you invoke your “birthday
party” schema, you don’t have to sort through irrelevant knowledge in your memory—
such as information contained in your “attending class” schema or your “dinner at a
restaurant” schema. See for yourself how helpful schemas can be in the Do It Yourself
box on this page.
Schemas, then, can be an aid to declarative long-term memory when they help us
make sense out of new information by giving us a ready-made framework for it. On
the other hand, they frequently lead us astray when it comes to details—as you may
have realized in the Do It Yourself box. The problem is that we aren’t usually aware
of those memory errors when we make them. We will have a closer look at problems
resulting from schema bias in the last part of this chapter.
Early Memories Most people have difficulty remembering events that happened before
their third birthday, a phenomenon called childhood amnesia. This suggests that younger
children have limited episodic memory ability. Learning clearly occurs, however, long
before age 3, probably from the moment of birth. We see this in a baby who learns to
recognize a parent’s face or in a toddler learning language. Thus, we know that very
young children have, at least, a semantic memory and a procedural memory.
Until recently, psychologists thought childhood amnesia occurs because young chil-
dren’s brains have not yet formed neural connections required for episodic memory.
Now, however, we know that the brain has begun to create necessary circuits by the
end of the first year of life. For example, cognitive scientists have found children as
young as 9 months showing some signs of episodic memory in the ability to imitate
behaviors they have observed after a delay (Bauer et al., 2003). So why can’t you re-
member your first birthday party? Part of the answer probably involves rudimentary
language skills (for verbal encoding of memories), the lack of a sense of self (necessary
as a reference point, but which doesn’t develop until about age 2), and the lack of the
complex schemas older children and adults use to help them remember.
Culture also influences people’s early memories. For example, the earliest memories
of Maori New Zealanders go back to 2.5 years, while Korean adults rarely remember
anything before the age of 4. The difference seems to depend on how much the culture
encourages children to tell detailed stories about their lives. “High elaborative” parents
childhood amnesia The inability to remember
events during the first two or three years of life.
HOW SCHEMAS IMPACT MEMORY
Read the following passage carefully:
Chief Resident Jones adjusted his
face mask while anxiously surveying
a pale figure secured to the long
gleaming table before him. One swift
stroke of his small, sharp instrument
and a thin red line appeared. Then
the eager young assistant carefully
extended the opening as another aide
pushed aside glistening surface fat
so that the vital parts were laid bare.
Everyone stared in horror at the ugly
growth too large for removal. He now
knew it was pointless to continue.
Now, without looking back, please
complete the following exercise. Circle
below the words that appeared in the
passage:
patient scalpel blood tumor
cancer nurse disease surgery
In the original study, most of the
subjects who read this passage circled the
words patient, scalpel, and tumor. Did you?
However, none of the words were there!
Interpreting the story as a medical story
made it more understandable, but also
resulted in inaccurate recall (Lachman
et al., 1979). Once the subjects had
related the story to their schema for
hospital surgery, they “remembered” labels
from their schema that were not present
in what they had read. So while schemas
help us organize information, they also
create ample opportunity for errors in
encoding and retrieval—which may create
false memories, as we unconsciously
modify information to make it more consis-
tent with our schema-based expectations.

How Do We Form Memories? 187
spend a lot of time encouraging children to talk about their daily experiences. This seems
to strengthen early memories, enabling them to persist into adulthood (Leichtman, 2006;
Winerman, 2005a).
The Biological Basis of Long-Term Memory Scientists have searched for the
engram, the biological basis of long-term memory, for more than a century. One of their
tactics involves looking for neural circuitry the brain uses to forge memories. Another
approach goes to the level of synapses, looking for biochemical changes that might
represent the physical memory trace within nerve cells. A tragic figure known as H. M.,
whom we met in Chapter 2, represents the first of these two approaches.
Clues from the Case of H. M. As a young man in 1953, H. M. lost most of his ability
to form new memories—the result of an experimental brain operation performed as
a last-ditch effort to treat his frequent epileptic seizures (Corkin, 2002; Hilts, 1995).
From that point on, he was almost completely unable to create new memories of
events in his life. So profound was his memory impairment that he never even learned
to recognize the people who cared for him in the decades after his surgery.
Remarkably, H. M.’s memory for events prior to the operation remained normal,
even as new experiences slipped away before he could store them in LTM. He knew
nothing of the 9/11 attacks, the moon landings, or the computer revolution. He
couldn’t remember what he had for breakfast or the name of a visitor who left two
minutes before. Ironically, one of the few things he was able to retain was that he had
a memory problem. Even so, he was mildly surprised to see an aging face in the mir-
ror, expecting the younger man he had been in 1953 (Milner et al., 1968; Rosenzweig,
1992). Yet, throughout his long ordeal, he maintained generally good spirits and worked
willingly with psychologist Brenda Milner, whom he never could recognize, even after
working with her for years.
H. M.’s medical record listed his condition as anterograde amnesia—which means
a disability in forming new memories. To put the problem in cognitive terms, H. M.
had a severe impairment in his ability to transfer new concepts and experiences from
working memory to long-term memory (Scoville & Milner, 1957). From a biological
perspective, the cause was removal of the hippocampus and amygdala on both sides of
his brain (see Figure 5.9).
What did we learn from H. M.? Again speaking biologically, he taught us that
the hippocampus and amygdala are crucial to laying down new declarative memo-
ries, although they seem to have no role in retrieving old (well-remembered) memories
(Bechara et al., 1995; Wirth et al., 2003). Further, as we will see in a moment, H. M.’s
case helped us understand the distinction between procedural memories and declara-
tive memories. Remarkably, H. M. remained upbeat about his condition—even joking
engram The physical changes in the brain associ-
ated with a memory. It is also known as the memory trace.
New Zealand Maoris often remember
events from when they were 21/2 years
old—probably because their culture en-
courages children to tell stories about
their lives.
anterograde amnesia The inability to form
new memories (as opposed to retrograde amnesia,
which involves the inability to remember information
previously stored in memory).
FIGURE 5.9
The Hippocampus and Amygdala
The hippocampus and amygdala were
surgically removed from both sides of
H. M.’s brain. To help yourself visualize
where these structures lie, compare the
drawing with the MRI image. The MRI
shows the brain in cross section, with a
slice through the hippocampus visible
on each side.
Amygdala
Hippocampus
Hippocampus
Imagine if you looked into a mirror
expecting to see a young version of yourself
but instead saw yourself aged 30 or
40 years. This is what happened with H.M.

188 C H A P T E R 5 Memory
about his inability to remember—although, ironically, the removal of his amygdalas
may have contributed to his positive disposition (Corkin, 2002).
Parts of the Brain Associated with Long-Term Memory In the last two decades, neurosci-
entists have added much to the picture H. M. gave us of human memory. We now
know the hippocampus (see Figure 5.9) is implicated in Alzheimer’s disease, which also
involves loss of ability to make new declarative memories. Neuroscientists have also
discovered that the hippocampus’s neural neighbor, the amygdala, processes memo-
ries that have strong emotional associations (Bechara et al., 1995). These emotional
associations, it seems, act as an aid for quick access and retrieval (Dolan, 2002). The
amygdala, then, plays a role in the persistent and troubling memories reported by sol-
diers and others who have experienced violent assaults. In some cases, these memories
can be so disturbing that they constitute a condition known as posttraumatic stress
disorder. Importantly, this same biological basis of emotional memories contributes to
the lasting quality of most traumatic memories.
Are memories, then, stored in the hippocampus and the amygdala? No. Memories
for events and information (declarative memories) are actually stored throughout the
cerebral cortex, with various pieces of a memory each stored in the part of the cortex
that initially processed that particular sensory signal. So, for example, the memory of
the great vacation you had at the beach last summer would have the visual compo-
nents of the memory in your visual cortex, the sounds in the auditory cortex, the smells
in the olfactory bulb, the sequence of events in the frontal lobes, and so forth. And, if
you learned how to surf while you were there, that memory would be linked to the cer-
ebellum and the motor cortex—just like other procedural memories that involve body
movements and muscle memory.
How, you might wonder, do all these memory fragments get put back together
properly? (In other words, how does the surfing memory end up with the other beach
memories, rather than being misfiled with memories of your last visit to the dentist?)
While the technical details of this fantastic feat remain a mystery to neuroscientists,
we do know one part of the brain that plays a starring role. In the process known as
memory consolidation, memories gradually become more permanent with the help of the
hippocampus. Essentially, each time we retrieve a new declarative memory, pieces of that
memory from all over the brain come together in the hippocampus, which somehow
sorts through them and re-assembles the relevant ones into a coherent memory. Each
time, the neural pathway for that particular memory becomes stronger, so eventually the
memory doesn’t need the hippocampus to bind it together. At that point, any single piece of
the memory (for example, the smell of the ocean) is enough to produce the entire memory.
Understanding more about memory storage and consolidation reveals why H. M.
could not form new declarative memories—without hippocampi, his brain was missing
the hardware needed for these projects. It also explains why his ability to form new
procedural memories remained intact—as these memories do not involve the hippo-
campus. And, for those of us with intact hippocampi, researchers report that new ex-
periences consolidate much more rapidly if they are associated with existing memory
schemas (Squire, 2007; Tse et al., 2007). For you, that might mean connecting what
you learned about the hippocampus in Chapter 2 with the new information about its
role in consolidation that you are learning here.
Memories, Neurons, and Synapses A standard plot in soap operas and movies depicts
a person who develops amnesia (loss of memory) after a blow or injury to the head.
But does research support this soap-opera neuroscience? At the level of individual
neurons, memories form initially as fragile chemical traces at the synapse and con-
solidate into more permanent synaptic changes over time. During this consolidation
process, memories are especially vulnerable to interference by new experience, cer-
tain drugs, or a blow to the head (Doyère et al., 2007). The diagnosis, in the event of
significant memory loss, would be retrograde amnesia or loss of prior memory. (Note
that retrograde amnesia is the opposite of H. M.’s problem, anterograde amnesia,
which was the inability to form new memories.)
C O N N E C T I O N CHAPTER 14
Lasting biological changes may
occur in the brains of individuals
with posttraumatic stress disorder
(p. 605).
consolidation The process by which short-term
memories become long-term memories over a period
of time.
retrograde amnesia The inability to remember
information previously stored in memory. (Contrast with
anterograde amnesia.)
Watch the Video
at MyPsychLab
What Happens with
Alzheimer’s

How Do We Form Memories? 189
Memories can be strengthened, as well as weakened, during consolidation—
especially by a person’s emotional state. Research shows, however, that positive and
negative emotions have vastly different effects on attention and therefore on mem-
ory. If you are happy, you tend to look at situations broadly and remember the “big
picture.” But if you are being robbed at gunpoint, you will most likely attend to the
gun while paying less attention to details of the robber’s appearance. In general, we can
say that emotional arousal accounts for our most vivid memories, but not our most
precise ones: The scope of happy memories tends to be larger, as negative emotions
tend to restrict the focus of our memories (Dingfelder, 2005; Levine & Bluck, 2004).
Before leaving this section, we should note that from an evolutionary perspective, emo-
tion plays a highly adaptive role in memory. If you survive a frightening encounter with a
bear, for example, you are likely to remember to avoid bears in the future. For this, we can
thank the amygdala, as well as emotion-related chemicals such as epinephrine (adrenalin)
and certain stress hormones. Together, they enhance memory for emotion-laden experi-
ences via the “supercharged” emotional associations they create (McGaugh, 2000).
PSYCHOLOGY MATTERS
“Flashbulb” Memories: Where Were You When . . . ?
The closest most people will come to having a “photographic memory” is a flashbulb
memory, an exceptionally clear recollection of an important and emotion-packed event
(Brown & Kulik, 1977). You probably harbor several such memories: a graduation,
a tragic accident, a death, a big victory. It feels as though you made a flash picture in
your mind of the striking scene. (The term was coined in the days when flash pho-
tography required a “flashbulb” for each picture.) The defining feature of a flashbulb
memory is the source of the memory (Davidson et al., 2005): vivid images of where
the individuals were at the time they received the news, what they were doing, and the
emotions they felt.
Many people form flashbulb memories of emotionally charged events in the news,
such as the death of Michael Jackson, the September 11 attacks, or the election of
Barack Obama as president (Pillemer, 1984; Schmolck et al., 2000). Cognitive psychol-
ogists take advantage of these naturally occurring opportunities for research, and in
this case, use them to find the answer to this important question: Does the emotionally
charged nature of flashbulb memories affect their accuracy?
One study at Duke University collected students’ memories of the September 11
attacks the day after the event (Talarico & Rubin, 2003). Researchers also gathered
memories of a normal, everyday event from the same participants. Thirty-two weeks
later, participants’ memories were tested for accuracy. The result? On average, flash-
bulb memories were no more accurate than everyday memories—both types of memo-
ries declined in accuracy over time. Importantly, however, participants’ confidence in
the flashbulb memories was quite high: Students were more confident about the ac-
curacy of their flashbulb memories than their everyday memories, but it was false con-
fidence. Significantly, confidence level for the flashbulb memories correlated with the
initial level of emotional arousal during the flashbulb event. Other studies have corrob-
orated the notion that emotional arousal increases the vividness of the memory—but
not necessarily the accuracy of the memory.
How do we make sense of these findings, given the strong evidence that exists
for enhanced recollection of personal emotional events? First, we must note that
flashbulb memories are rarely the same as a memory of personal involvement in
a traumatic event. Flashbulb memories are often of publicly known, widely shared
events—on an individual level, we may not have personal involvement in the situa-
tion. Thus, the public event is likely to be all over the news, discussed widely, and
retold frequently. And in these frequent tellings, by many different people, details are
likely to become distorted.
flashbulb memory A clear and vivid long-term
memory of an especially meaningful and emotional
event.
Do you remember where you were and
how you felt when Barack Obama won the
2008 Presidential Election? Chances are,
your flashbulb memory is not as accurate
as you think it is.

190 C H A P T E R 5 Memory
As the saying goes, then, the devil may be in the details. Flashbulb memory studies
reveal that certain vivid details are often remembered with great accuracy, but also—
especially over time—other, equally vivid details fail the accuracy test. One study
of Israeli students, in the wake of the assassination of Prime Minister Itzhak Rabin,
found that only about two-thirds of vividly reported memories were still accurate
after 11 months (Nachson & Zelig, 2003)—although confidence in the erroneous
memories remained high. As we noted earlier, traumatic events narrow the scope of
our attention; thus, we encode only certain details and later fill in that sketch—quite
unconsciously—with details we have heard from others or details that fit our schema
for the event.
Even though this creates the potential for memory errors, the mistaking of confi-
dence for accuracy may serve an adaptive purpose. Evolutionary psychologists suggest
that, in times of stress, the ability to make a quick and confident decision might make
the difference between life and death (Poldrack et al., 2008). In that way as well, the
devil may truly be in the details.
5.3 KEY QUESTION
How Do We Retrieve Memories?
Memory can play several surprising tricks during retrieval. One involves the possibility
of retrieving a memory you didn’t know you had—which tells us some memories can
be successfully encoded and stored without full awareness. Another quirk involves our
confidence in recollections—as we saw in flashbulb memories. Our Core Concept
summarizes the retrieval process this way:
Core Concept 5.3
Whether memories are implicit or explicit, successful retrieval
depends on how they were encoded and how they are cued.
Implicit and Explicit Memory
We begin our exploration of retrieval with another lesson from H. M. You may recall
that he retained the ability to learn new motor skills, even though he lost most of his
ability to remember facts and events. For example, H. M. learned the difficult skill of
Check Your Understanding
1. RECALL: Which part of memory has the smallest capacity? (That
is, which part of memory is considered the “bottleneck” in the
memory system?)
2. RECALL: Which part of long-term memory stores autobiographical
information?
3. RECALL: To get material into permanent storage, it must be made
meaningful while it is in .
4. APPLICATION: As you study vocabulary in this text, which of the
following methods would result in the deepest level of processing?
a. learning the definition given in the marginal glossary
b. marking each term with a highlighter each time it occurs in a
sentence in the text
c. thinking of an example of each term
d. having a friend read a definition, with you having to identify the
term in question form, as on the TV show Jeopardy
5. UNDERSTANDING THE CORE CONCEPT: As the information
in this book passes from one stage of your memory to the next, the
information becomes more .
Answers 1. Working memory 2. Episodic memory 3. working memory 4. c 5. meaningful and associated with other information in LTM
Study and Review at MyPsychLab

How Do We Retrieve Memories? 191
mirror writing—writing while looking at his hands in a mirror (Milner et al., 1968;
Raymond, 1989). In fact, his procedural memory for motor tasks was quite normal, even
though he couldn’t remember learning these skills and didn’t even know he knew them.
But you don’t have to have brain damage like H. M. to have memories of which you
are unaware. A normal memory has disconnected islands of information too. For more
than 100 years, psychologists have realized that people with no memory defects can
know something without knowing they know it. Psychologist Daniel Schacter (1992,
1996) calls this implicit memory: memory that can affect your behavior without coming
into full awareness. By contrast, explicit memory requires conscious awareness.
Procedural memories are often implicit, as when golfers remember how to swing
a club without thinking about how to move their bodies. Likewise, H. M.’s mirror
writing was an implicit memory. But implicit memories are not limited to procedural
memory—nor is explicit memory the same as declarative memory. Information in your
semantic store can be either explicit (such as in remembering the material you have
studied for a test) or implicit (such as knowing the color of the building in which your
psychology class is held). The general rule is this: A memory is implicit if it can affect
behavior or mental processes without becoming conscious. Explicit memories, on the
other hand, always involve consciousness during storage and retrieval.
In striking new studies, Skotko et al. (2004) found that H. M. could learn some
new semantic material through implicit channels—that is, even though he didn’t know
he learned it. To do this, Skotko’s group exploited H. M.’s favorite pastime of doing
crossword puzzles. They devised crosswords that linked new information with knowl-
edge H. M. had at the time of his operation: For example, H. M. knew that polio was a
dreaded disease, but the polio vaccine was not discovered until after his surgery, so he
had no knowledge of it. Yet by working on a specially designed crossword puzzle over
a five-day period, H. M. learned to respond correctly to the item, “childhood disease
successfully treated by Salk vaccine.” Similarly, he was able to learn that Jacqueline
Kennedy, wife of assassinated President John Kennedy, subsequently became Jacque-
line Onassis. This technique, then, showed that H. M.’s problem was primarily one of
explicit memory.
Retrieval Cues
For accurate retrieval, both implicit and explicit memories require good cues. You have
some understanding of such cues if you’ve ever used search terms in Google or an-
other Internet search engine: Make a poor choice of terms, and you come up either
with nothing or with Internet garbage. Long-term memory works much the same way,
where a successful search requires good mental retrieval cues (the “search terms” used
to recover a memory). Sometimes the only retrieval cue required to reactivate a long-
dormant experience is a certain odor, such as the smell of fresh-baked cookies you
associated with visiting Grandma’s house. Other times, the retrieval cue might be an
emotion, as when a person struggling with depression gets caught in a maelstrom
of depressing memories. In our story of Ross at the beginning of the chapter, some-
thing in his dream may have served as a retrieval cue for the memory he had long
forgotten.
On the other hand, some memories—especially semantic ones—are not so easily
cued. During a test, for example, you may draw a blank if the wording of a question
doesn’t match the way you framed the material in your mind as you were studying. In
other words, your memory may fail if the question isn’t a good retrieval cue. In gen-
eral, whether a retrieval cue is effective depends on the type of memory being sought
and the web of associations in which the memory is embedded. The take-home lesson
here? The more extensive your web of associations, the greater the chance of retrieving
the information. Let’s examine ways you can use this information to your advantage.
Retrieving Implicit Memories by Priming A quirk of implicit memory landed for-
mer Beatle George Harrison in court (Schacter, 1996). Lawyers for a singing group
known as the Chiffons claimed the melody in Harrison’s song “My Sweet Lord” was
implicit memory A memory that was not
deliberately learned or of which you have no conscious
awareness.
explicit memory Memory that has been
processed with attention and can be consciously
recalled.
retrieval cue Stimulus used to bring a memory to
consciousness or to cue a behavior.
H.M.’s Obituary from The New York
Times
Read
at MyPsychLab

192 C H A P T E R 5 Memory
nearly identical to that of the Chiffon classic “He’s So Fine.” Harrison denied that
he deliberately borrowed the melody, but conceded he had heard the Chiffons’s tune
prior to writing his own. The court agreed, stating that Harrison’s borrowing was a
product of “subconscious memory.” Everyday life abounds with similar experiences,
says Daniel Schacter (1996). You may have proposed an idea to a friend and had it
rejected, but weeks later your friend excitedly proposed the same idea to you, as if it
were entirely new.
In such real-life situations it can be hard to say what prompts an implicit memory
to surface. Psychologists have, however, developed ways to “prime” implicit memories
in the lab (Schacter, 1996). To illustrate, imagine you have volunteered for a memory
experiment. First, you are shown a list of words for several seconds:
assassin, octopus, avocado, mystery, sheriff, climate
Then, an hour later, the experimenter asks you to examine another list and indicate
which items you recognize from the earlier list: twilight, assassin, dinosaur, and mys-
tery. That task is easy for you. But then the experimenter shows you some words with
missing letters and asks you to fill in the blanks:
c h _ _ _ _ n k, o _ t _ _ u s, _ o g _ y _ _ _ , _ l _ m _ t e
It is likely that answers for two of these pop readily into mind, octopus and climate.
But chances are that you will be less successful with the other two words, chipmunk
and bogeyman. This difference is due to priming, the procedure of providing cues that
stimulate memories without awareness. Because you had been primed with the words
octopus and climate, they more easily “popped out” in your consciousness than did
words that had not been primed.
Retrieving Explicit Memories Anything stored in LTM must be “filed” according
to its pattern or meaning. Consequently, the best way to add material to long-term
memory is to associate it, while in working memory, with material already stored in
LTM. We have called that process elaborative rehearsal. Encoding many such connec-
tions by elaborative rehearsal gives you more ways of accessing the information, much
as a town with many access roads can be approached from many directions.
Meaningful Organization One way of retrieving information from explicit memory
involves getting the general idea or gist of an event, rather than a memory of the event
as it actually occurred. Suppose you hear the sentence, “The book was returned to
the library by Mary.” Later, when asked if you heard the sentence, “Mary returned
the book to the library,” you may indeed mistakenly remember having heard the sec-
ond sentence. This happens because we tend to remember the meaning or sense of the
words—the gist—rather than the exact words themselves.
If you’ll forgive us for repeating ourselves, we want to underscore the practical
consequences of LTM being organized by meaning. Storing new information in
LTM usually requires that you make the information meaningful while it is in work-
ing memory. This means that you must associate new information with things you
already know. Sometimes it is important to remember all the details accurately (as
in memorizing a mathematical formula), while at other times the important thing is
to remember the gist (as when you read the case study of H. M.). In attempting to
remember the gist, it is especially important to think of personal examples of the con-
cepts and ideas you want to remember. (Are you getting into the habit of identifying
personal examples of chapter concepts yet?)
Recall and Recognition Explicit memories can be cued in two primary ways. One
involves the kinds of retrieval cues used on essay tests; the other involves cues found
on multiple choice tests. Essay tests require recall or retrieving a memory with minimal
retrieval cues. That is, on an essay test, you must create an answer almost entirely from
memory, with the help of only minimal cues from a question such as, “What are the
two ways to cue explicit memories?”
C O N N E C T I O N CHAPTER 8
Priming is also a technique for
studying nonconscious processes
(p. 329).
priming A technique for cuing implicit memories
by providing cues that stimulate a memory without
awareness of the connection between the cue and the
retrieved memory.
gist (pronounced JIST ) The sense or meaning, as
contrasted with the exact details.
recall A retrieval method in which one must
reproduce previously presented information.

How Do We Retrieve Memories? 193
Recognition, on another hand, is the method required by multiple-choice tests. In a
recognition task, you merely identify whether a stimulus has been previously experi-
enced. Normally, recognition is less demanding than recall because the cues are much
more complete. Incidentally, the reason people say, “I’m terrible with names, but I never
forget a face,” is because recall (names) is usually tougher than recognition (faces).
The police use recognition when they ask an eyewitness to identify a suspect in
a lineup. The witness is required only to match an image from memory (the crime)
against a present stimulus (a suspect in the lineup). And what would be a comparable
recall task? A witness working with a police artist to make a drawing of a suspect must
recall, entirely from memory, the suspect’s facial characteristics.
Of course, recognizing a previously recognized stimulus doesn’t necessarily mean
that stimulus matches the current context. We run into this problem on multiple-choice
exams when several options offer concepts we have learned, but only one of them is a
match to the particular question. Similarly, suspects have been falsely identified in po-
lice lineups by eyewitnesses if, for example, police have shown the eyewitness books of
mug shots that include one or more of the suspects in the lineup. In these cases, eyewit-
nesses can mistakenly identify a suspect because they recognize him from the mug shot
book rather than the actual crime (Weiner et al., 2003). Thus, although recognition
generally produces more memories than recall, it also is more likely to produce false
positives—or, in this case, false memories.
Other Factors Affecting Retrieval
We have seen that the ability to retrieve information from explicit declarative memory
depends on whether the information was encoded and elaborated to make it mean-
ingful. You won’t be surprised to learn that alertness, stress level, drugs, and general
knowledge also affect retrieval. Less well known, however, are the following, which
relate to the context in which you encoded a memory and also the context in which
you are remembering.
Encoding Specificity The more closely retrieval cues match the form in which the
information was encoded, the better they will cue the appropriate memory. For ex-
ample, perhaps you saw your psychology professor at the grocery store, but needed a
moment to recognize who she or he was because the context didn’t cue you to think
“psychology professor.” On the other hand, talking to a childhood friend may have
cued a flood of memories you hadn’t thought about for years. These two experiences
illustrate the encoding specificity principle, which says successful recall depends on how
well retrieval cues match cues present when the memory was encoded.
So, one important thing you can do in studying for exams is to anticipate what
retrieval cues are likely to be on the test and organize your learning around those
probable cues. Students who merely read the material and hope for the best may have
trouble. In fact, this is such a common problem that psychologist Robert Bjork (2000)
has suggested teachers introduce “desirable difficulties” into their courses to encour-
age students to encode the material in multiple ways. What are desirable difficulties?
Bjork argues that by giving students assignments that require them to interact with
the material in many different ways—projects, papers, problems, and presentations—
professors help students build a greater web of associations into which a memory is
embedded—and the more connections there are, the easier it becomes to cue a memory.
If your own professor doesn’t do this, what can you do to create more associations with
the concepts you are learning?
Mood and Memory Information processing isn’t just about facts and events; it’s also
about emotions and moods. We use the expressions “feeling blue” and “looking at
the world through rose-colored glasses” to acknowledge that moods bias our percep-
tions. Likewise, our moods can also affect what we remember, a phenomenon called
mood-congruent memory. If you have ever had an episode of uncontrollable giggling,
you know how a euphoric mood can trigger one silly thought after another. And at
recognition A retrieval method in which one must
identify present stimuli as having been previously
presented.
encoding specificity principle The doctrine
that memory is encoded and stored with specific cues
related to the context in which it was formed. The more
closely the retrieval cues match the form in which
the information was encoded, the better it will be
remembered.
mood-congruent memory A memory process
that selectively retrieves memories that match (are
congruent with) one’s mood.

194 C H A P T E R 5 Memory
the other end of the mood spectrum, people with depression often report that all their
thoughts have a melancholy aspect. In this way, depression can perpetuate itself through
retrieval of depressing memories (Sakaki, 2007).
Not just a laboratory curiosity, mood-congruent memory can also have important
health implications. Says memory researcher Gordon Bower, “Doctors assess what
to do with you based on your complaints and how much you complain” (McCarthy,
1991). Because people with depression are likely to emphasize their medical symp-
toms, they may receive different treatment from that dispensed to more upbeat indi-
viduals with the same disease. This, says Bower, means physicians must learn to take
a person’s psychological state into consideration when deciding on a diagnosis and a
course of therapy.
Prospective Memory One of the most common memory tasks involves remembering
to perform some action at a future time—such as keeping a doctor’s appointment,
going to lunch with a friend, or setting out the garbage cans on the appointed day.
Psychologists call this prospective memory. Surprisingly, this important process of
remembering to remember has received relatively little study. We do know a failure
in prospective memory can have consequences that range from merely inconvenient
and embarrassing to horrific:
After a change in his usual routine, an adoring father forgot to turn toward
the day care center and instead drove his usual route to work at the university.
Several hours later, his infant son, who had been quietly asleep in the back seat,
was dead (Einstein & McDaniel, 2005, p. 286).
How could such a terrible thing happen? The father probably became distracted from
his intended task and fell into his customary routine. In situations like this, when peo-
ple have to remember to deviate from their usual routine, they typically rely on contin-
uous monitoring, which means trying to keep the intended action in mind. Continuous
monitoring, however, can be easily derailed by distraction or habit. So if you find your-
self in that situation, your best bet is to use a reliable prompt—which for the father
may have meant placing his briefcase in the backseat with his child. Another good
technique involves thinking of a specific cue you expect to encounter just before the
required task. The father, for example, might have visualized a prominent landmark he
would see just before the turn off his usual route and then focused on that landmark
as a memory cue.
PSYCHOLOGY MATTERS
On the Tip of Your Tongue
Answer as many of the following questions as you can:
• What is the North American equivalent of the reindeer?
• What do artists call the board on which they mix paints?
• What is the name for a tall, four-sided stone monument with a point at the top
of its shaft?
• What instrument do navigators use to determine latitude by sighting on the stars?
• What is the name of a sheath used to contain a sword or dagger?
• What is the name of a small Chinese boat usually propelled with a single
oar or pole?
If this demonstration works as expected, you couldn’t remember all the answers,
but you had a strong sense you had them somewhere in memory. You might say that
the answer was “on the tip of your tongue.” Appropriately enough, psychologists refer
to this near-miss memory as the TOT phenomenon (Brown, 1991). Surveys show that
prospective memory The aspect of memory
that enables one to remember to take some action in
the future—as remembering a doctor’s appointment.
TOT phenomenon The inability to recall a
word, while knowing that it is in memory. People often
describe this frustrating experience as having the word
“on the tip of the tongue.”
The Washington Monument is an example
of a tapered stone object that is topped
by a pyramid-shaped point. Can you recall
the name for such objects? Or is it “on
the tip of your tongue”?
Because mood affects memory, people
with depression may remember and report
more negative symptoms to a physician.
As a result, their treatment may differ
from that given to patients with the same
condition who do not have depression.

Why Does Memory Sometimes Fail Us? 195
most people have a “tip-of-the-tongue” (TOT) experience about once a week. Among
those who watch Jeopardy, it may occur even more frequently. And, according to a
recent study, deaf persons who use sign language sometimes have a “tip of the fingers”
(TOF) experience in which they are sure they know a word but cannot quite retrieve
the sign (Thompson et al., 2005). Obviously, then, some fundamental memory process
underlies both the TOT and the TOF phenomena.
The most common TOT experiences center on names of personal acquaintances,
names of famous persons, and familiar objects (Brown, 1991). About half the time, target
words finally do pop into mind, usually within about one agonizing minute (Brown &
McNeill, 1966).
What accounts for the TOT phenomenon? One possibility—often exploited in
laboratory studies—involves inadequate context cues. This is probably what made you
stumble on some of the items above: We did not give you enough context to activate
the schema associated with the correct answer.
Another possibility involves interference: when another memory blocks access or
retrieval, as when you were thinking of Jan when you unexpectedly meet Jill (Schacter,
1999). And, even though you were unable to recall some of the correct words in our
demonstration of TOT (caribou, palette, obelisk, sextant, scabbard, sampan), you may
have spotted the right answer in a recognition format. It’s also likely that some features
of the sought-for words abruptly popped to mind (“I know it begins with an s!”), even
though the words themselves eluded you. So the TOT phenomenon occurs during a
recall attempt when there is a weak match between retrieval cues and the encoding of
the word in long-term memory.
And we’ll bet you can’t name all seven dwarfs.
5. RECALL: A person experiencing the TOT phenomenon is unable
to _____ a specific word.
a. recognize c. recall
b. encode d. process
6. UNDERSTANDING THE CORE CONCEPT: An implicit memory
may be activated by priming, and an explicit memory may be
activated by a recognizable stimulus. In either case, a psychologist
would say that these memories are being
a. cued. c. encoded.
b. recognized. d. chunked.
Study and Review at MyPsychLabCheck Your Understanding
1. APPLICATION: Remembering names is usually harder than
remembering faces because names require , while faces
merely require .
2. APPLICATION: At a high school class reunion, you are likely
to experience a flood of memories that would be unlikely to come to
mind under other circumstances. What memory process
explains this?
3. APPLICATION: Give an example of mood-congruent memory.
4. APPLICATION: Give an example of a situation that would require
prospective memory.
Answers 1. recall/recognition 2. Encoding specificity 3. Good examples involve situations in which people who are feeling a strong emotion or mood
selectively remember experiences associated with that mood. Thus, during a physical exam, a depressed person might report more unpleasant
physical symptoms than would a happy person. 4. Prospective memory involves having to remember to perform some action at a time in the future,
such as taking medicine tonight, stopping at the grocery store on the way home, or calling one’s parents next Friday evening. 5. c 6. a
5.4 KEY QUESTION
Why Does Memory Sometimes Fail Us?
We forget appointments and anniversaries. During a test you can’t remember the terms
you studied the night before. Or a familiar name seems just out of your mental reach.
Yet, ironically, we sometimes cannot rid memory of an unhappy event. Why does
memory play these tricks on us—making us remember what we would rather forget
and forget what we want to remember?

196 C H A P T E R 5 Memory
According to memory expert Daniel Schacter, the culprit is what he terms the
“seven sins” of memory: transience, absent-mindedness, blocking, misattribution, sug-
gestibility, bias, and unwanted persistence (Schacter, 1999, 2001). Further, he claims
these seven problems are really consequences of some very useful features of human
memory. From an evolutionary perspective, these features stood our ancestors in good
stead, so they are preserved in our own memory systems. Our Core Concept puts this
notion more succinctly:
Core Concept 5.4
Most of our memory problems arise from memory’s “seven sins”—
which are really by-products of otherwise adaptive features of human
memory.
While examining the “seven sins,” we will consider such everyday memory prob-
lems as forgetting where you left your keys or the inability to forget an unpleasant
experience. We will also explore strategies for improving memory by overcoming some
of Schacter’s “seven sins”—with special emphasis on how certain memory techniques
can improve your studying. We begin with the frustration of fading memories.
Transience: Fading Memories Cause Forgetting
How would you do on a rigorous test of the course work you took a year
ago? We thought so—because unused memories seem to weaken with time.
Although no one has directly observed a human memory trace fade and
disappear, much circumstantial evidence points to this transience, or imper-
manence, of long-term memory—the first of Schacter’s “sins.”
Ebbinghaus and the Forgetting Curve In a classic study of transience,
pioneering psychologist Hermann Ebbinghaus (1908/1973) first learned
lists of nonsense syllables (such as POV, KEB, FIC, and RUZ) and tried to
recall them over varying time intervals. This worked well over short peri-
ods, up to a few days. But to measure memory after long delays of weeks
or months, when recall had failed completely, Ebbinghaus had to invent
another method: He measured the number of trials required to relearn the
original list. Because it generally took fewer trials to relearn a list than to
learn it originally, the difference indicated a “savings” that could serve as a
measure of memory. (If the original learning required ten trials and relearn-
ing required seven trials, the savings was 30 percent.) By using the savings
method, Ebbinghaus could trace memory over long periods of time. The
curve obtained from combining data from many experiments appears in
Figure 5.10 and represents one of Ebbinghaus’s most important discov-
eries: For relatively meaningless material, we have a rapid initial loss of memory
followed by a declining rate of loss. Subsequent research shows that this forgetting
curve captures the pattern of transience by which we forget much of the verbal
material we learn.
Modern psychologists have built on Ebbinghaus’s work but now have more inter-
est in how we remember meaningful material, such as information you read in this
book. Meaningful memories seem to fade too—though, fortunately, not as rapidly as
Ebbinghaus’s nonsense syllables. Current research sometimes uses brain scanning tech-
niques, such as fMRI and PET, to visualize the diminishing brain activity that charac-
terizes forgetting (Schacter, 1996, 1999).
Not all memories, however, follow the classic forgetting curve. We often retain well-
used motor skills, for example, substantially intact in procedural memory for many
years, even without practice—“just like riding a bicycle.” Memory for foreign lan-
guages learned, but not used for a long period of time, also seems to remain relatively
intact (subject to less forgetting than Ebbinghaus predicted) for as long as 50 years
transience The impermanence of a long-term
memory. Transience is based on the idea that long-term
memories gradually fade in strength over time.
forgetting curve A graph plotting the amount of
retention and forgetting over time for a certain batch of
material, such as a list of nonsense syllables. The typi-
cal forgetting curve is steep at first, becoming flatter
as time goes on.
C O N N E C T I O N CHAPTER 2
fMRI and PET are brain scanning
techniques that form images of
especially active regions in the
brain (p. 64).
FIGURE 5.10
Ebbinghaus’s Forgetting Curve
Ebbinghaus’s forgetting curve shows that the savings
demonstrated by relearning drops rapidly and reaches
a plateau, below which little more is forgotten.
Source: Zimbardo, P. G., & Gerrig, R. J. (1999). Psychology and
Life, 15th ed. Boston, MA: Allyn and Bacon. Copyright © 1999 by
Pearson Education. Reprinted by permission of the publisher.
Pe
rc
en
t
sa
vi
ng
s
Days
10
10
20
30
40
50
60
2345 10 15 20 25 30

Why Does Memory Sometimes Fail Us? 197
(Bahrick, 1984). Similarly, recognition of high-school classmates’ names and faces re-
mains about 90 percent accurate even up to 45 years (although recall-based memory
tasks show much lower retention; Bahrick, Bahrick, & Wittlinger, 1975). What ac-
counts for less transience in these areas? We’ll reveal the answer to that question near
the end of the chapter in our discussion of study tips.
Interference One common cause of transience comes from interference—when one
item prevents us from forming a robust memory for another item. This often occurs
when you attempt to learn two conflicting things in succession, such as if you had a
French class followed by a Spanish class.
What causes interference? Three main factors top the list:
1. The more similar the two sets of material to be learned, the greater the likelihood of
interference. So French and Spanish classes are more likely to interfere with each
other than are, say, psychology and accounting.
2. Meaningless material is more vulnerable to interference than meaningful material.
Because LTM is organized by meaning, you will have more trouble remembering
two locker combinations than you will two news bulletins. (The exception occurs
when you experience a direct conflict in meaning, as when two news bulletins
seem to be telling you conflicting things.)
3. Emotional material can be an especially powerful cause of interference. So if you broke
up with your true love last night, you will probably forget what your literature
professor says in class today.
Interference commonly arises when an old habit gets in the way of learning a new
response, as we saw in the case of the father who forgot to stop at the day care center.
Interference can also happen when people switch from one word-processing program
to another. And, of course, interference accounts for the legendary problem old dogs
have in learning new tricks. Everyday life offers many more examples, but interfer-
ence theory groups them in two main categories, proactive interference and retroactive
interference.
Proactive Interference When an old memory disrupts the learning and remembering of
new information, proactive interference is the culprit. An example of proactive interfer-
ence occurs every January when we have trouble remembering to write the correct date
on our checks. Pro- means “forward,” so in proactive interference, old memories act
forward in time to block your attempts at new learning.
Retroactive Interference When the opposite happens—when new information prevents
your remembering older information—we can blame forgetting on retroactive interference.
Retro- means “backward”; the newer material reaches back into your memory to push
old material out of memory (see Figure 5.11). In a computer, retroactive interference
occurs when you save a new document in place of an old one. Much the same thing
happens in your own memory when you meet two new people in succession, and the
second name causes you to forget the first one.
The Serial Position Effect Have you ever noticed that the first and last parts of a poem
or vocabulary list are usually easier to learn and remember than the middle portion? In
general, the primacy effect refers to the relative ease of remembering the first items in
a series, while the recency effect refers to the strength of memory for the most recent
items. Together, with diminished memory for the middle portion, we term this the
serial position effect. So when you are introduced to several people in succession, you
are more likely to remember the names of those you met first and last than those you
met in between. (That’s assuming other factors are equal, such as the commonness of
their names, distinctiveness of their appearance, and their personalities.)
How does interference theory explain the serial position effect? Unlike the material
at the ends of the poem or list, the part in the middle is exposed to a double dose of
interference—both retroactively and proactively. That is, the middle receives interference
proactive interference A cause of forgetting by
which previously stored information prevents learning
and remembering new information.
retroactive interference A cause of forgetting
by which newly learned information prevents retrieval
of previously stored material.
serial position effect A form of interference
related to the sequence in which information is pre-
sented. Generally, items in the middle of the sequence
are less well remembered than items presented first
or last.

198 C H A P T E R 5 Memory
from both directions, while material at either end gets interference from only one side.
So, in view of the serial position effect, perhaps it would be helpful to pay special
attention to the material in the middle of this chapter.
Absent-Mindedness: Lapses of Attention Cause Forgetting
When you misplace your car keys or forget an anniversary, you have had an episode
of absent-mindedness, the second “sin” of memory. It’s not that the memory has disap-
peared from your brain circuits. Rather, you have suffered a retrieval failure caused by
shifting your attention elsewhere. In the case of a forgotten anniversary, the attention
problem occurred on the retrieval end—when you were concentrating on something
that took your attention away from the upcoming anniversary. As for the car keys,
your attentive shift probably occurred during the original encoding—when you weren’t
paying attention to where you laid them. This form of absent-mindedness often comes
from listening to music or watching TV while studying.
This kind of encoding error was also at work in the “depth of processing”
experiments we discussed earlier: People who encoded information shallowly (“Does
the word contain an e?”) were less able to recall the target word than those who
encoded it deeply (“Is it an animal?”). Yet another example can be found in demon-
strations of change blindness: In one study, participants viewed a movie clip in which
one actor who was asking directions was replaced by another actor while they were
briefly hidden by two men carrying a door in front of them. Amazingly, fewer than half
the viewers noticed the change (Simons & Levin, 1998). Much the same thing may
happen to you in the magic trick demonstration in Figure 5.12.
Blocking: Access Problems
Blocking, the third “sin” of memory, occurs when we lose access to information, such
as when you see familiar people in new surroundings and can’t remember their names.
The most thoroughly studied form of blocking, however, involves the maddening TOT
absent-mindedness Forgetting caused by
lapses in attention.
blocking Forgetting that occurs when an item in
memory cannot be accessed or retrieved. Blocking is
caused by interference.
Study French
papier
chien
livre plume
proactive interference
Study Spanish
papel
perro
libro pluma
French 101
Midterm
exam
papier
livre
plume
chien
Study French
papier
chien
livre plume
retroactive interference
Study Spanish
Recall French
Recall Spanish
papel
perro
libro pluma
Spanish 101
Midterm
exam
papel
libro
pluma
perro
FIGURE 5.11
Two Types of Interference
In proactive interference, earlier learning
(Spanish) interferes with memory for later
information (French). In retroactive inter-
ference, new information (French) inter-
feres with memory for information learned
earlier (Spanish).
Misplacing your car keys results from a
shift in attention. Which of the seven
“sins” does this represent?

Why Does Memory Sometimes Fail Us? 199
experience: when you know you know the name for something but can’t retrieve it. As
we saw earlier, the TOT phenomenon often results from poor context cues that fail to
activate the necessary memory schema.
Stress, too, can produce blocking, perhaps through failure to sustain one’s focus of
attention. Similarly, distraction can cause blocking on prospective memory tasks, such
as remembering to perform a certain action at a certain time. Age plays a role, too,
with blocking increasing as one grows older.
Misattribution: Memories in the Wrong Context
All three “sins” discussed so far make memories unavailable in one way or another.
But these are not the only kinds of memory problems we experience. For example, we
sometimes retrieve memories but associate them with the wrong time, place, or person.
Schacter (1999) calls this misattribution, a problem that stems from the reconstructive
nature of long-term memory. In the penny demonstration at the beginning of the chapter,
you learned that we commonly retrieve incomplete memories and fill in the blanks to
make them meaningful to us. This paves the way for mistakes that arise from connect-
ing information with the wrong, but oh-so-sensible, context.
Here’s an example of misattribution: Psychologist Donald Thompson was
accused of rape based on a victim’s detailed, but mistaken, description of her assail-
ant (Thompson, 1988). Fortunately for Thompson, his alibi was indisputable. When
the crime occurred, he was being interviewed live on television—about memory dis-
tortions. The victim, it turned out, had been watching the interview just before she
was raped and, in the stress of the experience, misattributed the assault to Thompson,
recalling his face instead of the face of her assailant.
Misattribution can also prompt people to mistakenly believe that other people’s
ideas are their own. This sort of misattribution occurs when a person hears an idea
and keeps it in memory, forgetting its source. Unintentional plagiarism comes from
this form of misattribution, as we saw earlier in the case of George Harrison of the
Beatles.
Yet another type of misattribution can cause people to remember something
they did not experience at all. Such was the case with volunteers who were asked
to remember a set of words associated with a particular theme: door, glass, pane,
shade, ledge, sill, house, open, curtain, frame, view, breeze, sash, screen, and
shutter. Under these conditions, many later remembered window, even though that
word was not on the list (Roediger & McDermott, 1995, 2000). This result again
shows the power of context cues in determining the content of memory. And it
demonstrates yet again how people tend to create and retrieve memories based on
meaning.
misattribution A memory fault that occurs when
memories are retrieved but are associated with the
wrong time, place, or person.
FIGURE 5.12A
The “Magic of Memory”
Pick one of the cards. Stare at it intently
for at least 15 seconds, being careful not
to shift your gaze to the other cards. Then
turn the page.

200 C H A P T E R 5 Memory
Suggestibility: External Cues Distort or Create Memories
Suggestion can also distort or even create memories, a possibility of particular con-
cern to the courts. Attorneys or law enforcement officers interviewing witnesses may
make suggestions about the facts of a case—either deliberately or unintentionally—
that could alter a witness’s memory. Such concerns about suggestibility prompted
Elizabeth Loftus and John Palmer to find out just how easily eyewitness memories
could be distorted.
Memory Distortion Participants in the Loftus and Palmer study first watched a film of
two cars colliding. Then the experimenters asked them to estimate how fast the cars had
been moving (Loftus, 1979, 1984; Loftus & Palmer, 1973). Half the witnesses were asked,
“How fast were the cars going when they smashed into each other?” Their estimates, it
turned out, were about 25 percent higher than those given by respondents asked, “How
fast were the cars going when they hit each other?” This distortion of memory caused by
misinformation has been dubbed, appropriately, the misinformation effect.
Clearly, the Loftus and Palmer study showed that memories can be distorted and
embellished by even the most subtle cues and suggestions. But memories can also be
created by similar methods. And it can be done without an individual’s awareness.
Fabricated Memories The famed developmental psychologist, Jean Piaget (1962),
described a vivid memory of a traumatic event from his own early childhood:
One of my first memories would date, if it were true, from my second year. I can
still see, most clearly, the following scene in which I believed until I was about
fifteen. I was sitting in my pram, which my nurse was pushing in the Champs
Elysées [in Paris], when a man tried to kidnap me. I was held in by the strap fas-
tened round me while my nurse bravely tried to stand between me and the thief.
She received various scratches, and I can still see vaguely those on her face . . .
(pp. 187–188).
Piaget’s nurse described the alleged attack in vivid detail and was given an expen-
sive watch from his parents as a token of thanks for her bravery. However, years later,
the former nurse sent a letter to Piaget’s family confessing the story had been fabri-
cated and returning the watch. From this, Piaget (1962) concluded:
I, therefore, must have heard, as a child, the account of this story, which my
parents believed, and projected into the past in the form of a visual memory
(Piaget, 1962, p. 188).
suggestibility The process of memory distortion
as the result of deliberate or inadvertent suggestion.
misinformation effect The distortion of
memory by suggestion or misinformation.
FIGURE 5.12B
The “Magic of Memory”
Your card is gone! How did we do it? We
didn’t read your mind; it was your own
reconstructive memory and the “sin” of
absent-mindedness playing card tricks on
you. If you don’t immediately see how the
trick works, try it again with a different
card.
Memory:
Elizabeth Loftus
Watch the Video
at MyPsychLab

Why Does Memory Sometimes Fail Us? 201
Are we all susceptible to creating false memories such as the one Piaget described? To
find out, Elizabeth Loftus and her colleagues decided to do an experiment. They first
contacted parents of a group of college students, obtaining lists of childhood events,
which the students were then asked if they remembered. But embedded in those lists
were plausible events that never happened, such as being lost in a shopping mall, spill-
ing the punch bowl at a wedding, meeting Bugs Bunny at Disneyland (impossible be-
cause Bugs is not a Disney character), or experiencing a visit by a clown at a birthday
party (Loftus, 2003a). After repeated recall attempts over a period of several days,
about one-fourth of the students claimed to remember the bogus events. All that was
required were some credible suggestions. (This experiment may remind you of Donna’s
case, with which we began our chapter: Repeated suggestions by the therapist led to
Donna’s fabricated memory.)
New research suggests that doctored photographs can also create false memories,
perhaps even more powerfully than the stories used by Loftus and her colleagues. For
example, in a variation of the lost-in-the-mall technique, adults viewed altered photo-
graphs purporting to show them riding in a hot air balloon. After seeing the photos
several times over a period of two weeks, half the participants “remembered” details
about the fictitious balloon ride (Wade et al., 2002). Even in this age of digital cameras
and image-altering software, people don’t always stop to question whether a photo-
graph may have been modified (Garry & Gerrie, 2005).
Factors Affecting the Accuracy of Eyewitnesses So to what extent can we rely
on eyewitness testimony? Obviously, it is possible in laboratory experiments to dis-
tinguish false memories from true ones. But what about real-life situations in which
people claim to have recovered long-forgotten memories?
As we saw in our second case at the beginning of the chapter, Ross’s recollection
was independently verified by the confession of a camp counselor, but such objective
evidence doesn’t always materialize. In such cases, the best we can do is look for evi-
dence of suggestion that may have produced the memory—as we see in false-memory
experiments. If suggestion has occurred, a healthy dose of skepticism is warranted,
unless objective evidence appears. Specifically, we should beware of eyewitness reports
tainted by the following factors (Kassin, 2001):
• Leading questions (“How fast were the cars going when they smashed into each
other?”) can influence witnesses’ recollections. But such questions have less effect
if witnesses are forewarned that interrogations can create memory bias.
• The passage of substantial amounts of time, which allows the original memory to
fade, makes people more likely to misremember information.
• Repeated retrieval: Each time a memory is retrieved, it is reconstructed and then
restored (much like a computer document that is retrieved, modified, and saved),
increasing the chances of error.
• The age of the witness: Younger children and older adults may be especially
susceptible to influence by misinformation.
• Unwarranted confidence: Confidence in a memory is not a sign of an accurate
memory. In fact, misinformed individuals can actually come to believe the misin-
formation in which they feel confident.
Based on such concerns, the U.S. Department of Justice (1999) has published national
guidelines for gathering eyewitness testimony, available on its website.
Bias: Beliefs, Attitudes, and Opinions Distort Memories
The sixth memory “sin,” which Schacter calls bias, refers to the influence of personal
beliefs, attitudes, and experiences on memory. Lots of domestic arguments of the “Did
not! Did too!” variety owe their spirited exchanges to bias. While it’s easier to see an-
other person’s biases than our own, here are two common forms you should especially
guard against.
The way mug shots are presented can
bias the recollections of witnesses. Real-
izing this, the U.S. Department of Justice
has published guidelines for interrogating
eyewitnesses.

202 C H A P T E R 5 Memory
Expectancy Bias An unconscious tendency to remember events as being congruent
with our expectations produces expectancy bias. To illustrate, suppose you are among a
group of volunteers for an experiment in which you read a story about the relationship
between Bob and Margie, a couple who plan to get married. Part of the story reveals
that Bob doesn’t want children, and he is worried about how Margie will react to that.
When he does tell her, Margie is shocked, because she desperately wants children. To
your surprise, you are informed after reading the story that, contrary to your expecta-
tions, Bob and Margie did get married. Meanwhile, another group of volunteers reads
the same story but are told the couple ended their relationship. Other than the ending,
will people in those two groups remember the Bob and Margie story differently?
In a laboratory experiment using this same story, those who heard the unexpected
ending (the condition in which Bob and Margie decided to get married) gave the most
erroneous reports. Why? Because of their expectancy biases, they recalled distorted
information that made the outcome fit their initial expectations (Schacter, 1999; Spiro,
1980). One person, for example, “remembered” that Bob and Margie had separated
but decided their love could overcome their differences. Another related that the cou-
ple had decided on adoption as a compromise. When something happens that violates
our expectations, then, we may unconsciously skew the information so it better fits our
pre-existing notions.
Self-Consistency Bias People abhor the thought of being inconsistent, even
though research suggests that they are kidding themselves. This Schacter calls the
self-consistency bias. For example, studies have found people to be far less consistent
than they realized in their support for political candidates, as well as on political is-
sues such as the equality of women, aid to minority groups, and the legalization of
marijuana (Levine, 1997; Marcus, 1986).
Of particular interest for the study of memory, self-consistency bias can affect the
content of our memories (Levine & Safer, 2002). One study interviewed dating couples
twice, two months apart, and found memories about the relationship changed based
on how well the relationship had progressed over the two-month interval. Importantly,
though, participants generally did not recognize their inconsistencies. Those whose
relationships had improved remembered their initial evaluations of their partners as
more positive than they actually were, while those whose relationships had declined
had the opposite response (Scharfe & Bartholomew, 1998). In this study, as well as
many others involving attitudes, beliefs, opinions, or emotions, we see that our biases
act as a sort of distorted mirror in which our memories are reflected—but without our
awareness that our memories had been altered.
Persistence: When We Can’t Forget
The seventh “sin” of memory, persistence, reminds us that memory sometimes works
all too well. We all experience this occasionally, when a persistent thought, image, or
melody cycles over and over in our minds. Thankfully, such intrusive memories are
usually short lived. They can become a problem, though, when accompanied by intense
negative emotions. At the extreme, the persistence of memories for unpleasant events
creates a downward emotional spiral whereby people suffering from depression can’t
stop ruminating about unhappy events or traumas in their lives. Similarly, patients
with phobias may become obsessed by fearful memories about snakes, dogs, crowds,
spiders, or lightning. All of this underscores the powerful role that emotion plays in
memory.
The Advantages of the “Seven Sins” of Memory
Despite the grief they cause us, the “seven sins” arise from adaptive features of
memory, argues Daniel Schacter (1999). Thus, transience—maddening as it is to the
student taking a test—actually prevents the memory system from being overwhelmed
by information it no longer needs. Similarly, blocking is useful when it allows only the
self-consistency bias The commonly held idea
that we are more consistent in our attitudes, opinions,
and beliefs than we actually are.
C O N N E C T I O N CHAPTER 12
People with phobias have
extreme and unreasonable fears
of specific objects or situations
(p. 532).
persistence A memory problem in which
unwanted memories cannot be put out of mind.
expectancy bias The unconscious tendency
to remember events as being congruent with our
expectations.

Why Does Memory Sometimes Fail Us? 203
most relevant information—information most strongly associated with present cues—
to come to mind. These processes, then, help prevent us from a flood of unwanted and
distracting memories.
Absent-mindedness, too, is the by-product of the useful ability to shift our atten-
tion. Similarly, misattributions, biases, and suggestibility result from a memory system
built to focus on meaning and discard details: The alternative would be a computer-
like memory filled with information at the expense of understanding. And, finally, we
can see that the “sin” of persistence is really a feature of a memory system responsive
to emotional experiences, particularly those involving dangerous situations. In general,
then, the picture that emerges of memory’s “failures” is also a picture of a system well
adapted to conditions people have faced for thousands of years.
Improving Your Memory with Mnemonics
One way to improve your memory is to develop a tool kit of mental strategies known
as mnemonics (pronounced ni-MON-ix, from the Greek word meaning “remember”).
Mnemonic strategies help you encode new information by associating it with informa-
tion already in long-term memory. To illustrate, we will take a detailed look at two
mnemonic strategies, the method of loci and natural language mediators, both of
which are especially useful for remembering lists. Then we will offer tips to help with
the common problem of remembering names.
The Method of Loci Dating back to the ancient Greeks, the method of loci
(pronounced LOW-sye, from locus or “place”), is literally one of the oldest tricks in
this book. Greek orators originally devised the method of loci to help remember the
major points of their speeches.
To illustrate, imagine a familiar sequence of places, such as the bed, desk, and chairs
in your room. Then, using the method of loci, mentally move from place to place in the
room, and as you go imagine putting one item from your list in each place. To retrieve
the series, you merely take another mental tour, examining the places you used earlier.
There you will “see” the item you put in each place. To remember a grocery list, for ex-
ample, you might mentally picture a can of tuna on your bed, shampoo spilled on your
desktop, and a box of eggs open on a chair. Bizarre or unconventional image combina-
tions are usually easier to remember—so a can of tuna in your bedroom will make a
more memorable image than tuna in your kitchen (Bower, 1972).
It’s worth noting, by the way, that visual imagery is one of the most effective forms
of encoding: You can easily remember things by associating them with vivid, distinctive
mental pictures. In fact, you could remember your grocery list by using visual imagery
alone. Simply combine the mental images of tuna, shampoo, and eggs in a bizarre but
memorable way. So, you might picture a tuna floating on an enormous fried egg in a
sea of foamy shampoo. Or you might imagine a celebrity you dislike eating tuna from
the can, hair covered with shampoo suds, while you throw eggs at her.
Natural Language Mediators Memory aids called natural language mediators
associate meaningful word patterns with new information to be remembered. Using
this method to remember a grocery list, you would make up a story. Using the same
list as before (tuna, shampoo, and eggs), the story might link the items this way:
“The cat discovers I’m out of tuna so she interrupts me while I’m using the sham-
poo and meows to egg me on.” (OK, we know it’s hokey—but it works!) Similarly,
advertisers know that rhyming slogans and rhythmic musical jingles make it easier
for customers to remember their products and brand names (you may even have
one stuck in your head now!). The chances are that a teacher in your past used a
simple rhyme to help you remember a spelling rule (“I before E except after C”) or
the number of days in each month (“Thirty days has September . . . ”). In a physics
class, you may have used a natural language mediator in the form of an acronym—a
word made up of initials—to learn the colors of the visible spectrum in their correct
order: “Roy G. Biv” for red, orange, yellow, green, blue, indigo, violet.
mnemonic strategy Technique for improving
memory, especially by making connections between new
material and information already present in
long-term memory.
method of loci A mnemonic technique that
involves associating items on a list with a sequence
of familiar physical locations.
natural language mediator Word associated
with new information to be remembered.

204 C H A P T E R 5 Memory
Remembering Names The inability to remember people’s names is one of the most
common complaints about memory. So how could you use the power of association
to remember names? In the first place, know that remembering names doesn’t hap-
pen automatically. People who do it well work at it by making deliberate associations
between a name and some characteristic of the person—the more unusual the associa-
tion, the better.
Suppose, for example, you have just met us, the authors of this text, at a psycho-
logical convention. You might visualize Bob’s face framed in a big O, taken from the
middle of his name. To remember Vivian, think of her as “Vivacious Vivian,” the liveli-
est person at the convention. And, as for Phil, you might visualize putting a hose in
Phil’s mouth and “fill”-ing him with water. (While unusual associations may be easier
to remember than mundane ones, it is best not to tell people about the mnemonic you
have devised to remember their names.)
In general, use of mnemonics teaches us that memory is flexible, personal, and
creative. It also teaches us that memory ultimately works by meaningful associations.
With this knowledge and a little experimentation, you can devise techniques for encod-
ing and retrieval that work well for you, based on your own personal associations and,
perhaps, on your own sense of humor.
PSYCHOLOGY MATTERS
Using Psychology to Learn Psychology
Mnemonic strategies designed for learning names or memorizing lists of unrelated
items won’t help much with the material you need to learn in your psychology class.
There, the important material consists of concepts—often abstract concepts, such as
“operant conditioning” or “retroactive interference”—ideas you need to understand
rather than merely memorize. Such material calls for strategies geared both to concept
learning and to avoiding the two memory “sins” feared most by college students,
transience and blocking. Let’s see what advice cognitive psychologists have for students
trying to avoid these two quirks of memory.
Studying to Avoid Transience
• Make the material personally meaningful. Many studies have shown that memories
remain stronger when they are meaningful, rather than just a collection of facts and
definitions (Baddeley, 1998; Haberlandt, 1999). One good strategy for doing this
is the whole method, a technique often used by actors who must learn a script in a
short time. With this approach, begin by getting an overview of all the material—
the “big picture” into which details can be assimilated. Suppose, for example, you
have a test on this chapter next week. Using the whole method, you would read
through the chapter outline and summary, along with all the Key Questions and
Core Concepts on the chapter opening page, before beginning to read the details of
the chapter. This approach erects a mental framework on which you can hang the
details of encoding, interference, retrieval, and other memory topics.
• Spread your learning out over time. Next, use distributed learning to resist tran-
sience. In other words, study your psychology repeatedly and at frequent intervals
rather than trying to learn it all at once in a single “cram” session (called massed
learning). Distributed learning not only avoids the lowered efficiency of massed
learning, which causes fatigue, but also strengthens memories in the process of
consolidation. One study found that students who studied in two separate ses-
sions, rather than just one, doubled the amount of information they learned in
a given amount of time and also increased their understanding of the material
(Bahrick et al., 1993). Distributed learning also results in longer retention of mate-
rial (Schmidt & Bjork, 1992). And it helps us understand why we have enhanced
memory capabilities for names and faces of high school friends even decades
whole method The mnemonic strategy of first
approaching the material to be learned “as a whole,”
forming an impression of the overall meaning of the
material. The details are later associated with this
overall impression.
distributed learning A technique whereby the
learner spaces learning sessions over time rather than
trying to learn the material all in one study period.
Mnemonic strategies help us remember
things by making them meaningful. Here,
Wangari Maathai, the Nobel Peace Prize
laureate from Kenya, tries her hand at learn-
ing the Chinese character for “tree”—which
bears a resemblance to a stylized tree.
Many Chinese and Japanese characters
originally were drawings of the objects they
represented.

Why Does Memory Sometimes Fail Us? 205
later: We likely accessed that information frequently while in high school—the
equivalent of distributed learning.
• Take active steps to minimize interference. You can’t avoid interference altogether,
but you can avoid studying for another class after your review session for tomor-
row’s psychology test. And you can make sure you understand all the material and
have cleared up any confusing points well before you go to the test. If, for exam-
ple, you are not sure of the difference between declarative memory and semantic
memory, discuss this with your instructor—before the day of the test.
Studying to Avoid Blocking on the Test
The strategies above will help you get to the test with a strong memory for what you
need to know. To really do well on the test, though, you must also avoid blocking, the
inability to retrieve what you have in memory. To help you achieve this, we suggest
some techniques that apply two more ideas you learned in this chapter, elaborative
rehearsal and encoding specificity:
• Review and elaborate on the material. Students often think that, just because they
read the material once and understood it, they will remember it. With complex
concepts and ideas, though, you need to review what you have learned several
times. And your review should not be mindless and passive—merely looking at
the words in the book. Instead, use elaborative rehearsal. One of the best ways of
doing this when studying for a test is to create your own examples of the
concepts. So, as you study about proactive interference, think of an example from
your own experience. Also, review and rehearse mnemonics you may have created
for some of the material, such as acronyms or vivid mental images of concepts.
By adding associations to the material, you create more ways to access it when
you need it.
• Test yourself with retrieval cues you expect to see on the examination. By using
the principle of encoding specificity, you can learn the material in ways most likely
to be cued by the questions on the test. This is often easier to do with a friend
studying for the same test, ideally a few days before the exam, but after you have
already prepared and feel ready. Your purpose, at this point, will not be to learn
new material but to practice what you’ve learned as you anticipate the most likely
test items. Does your professor prefer essay questions? Short-answer questions?
Multiple choice? Try to think of and answer questions of the type most likely to
appear on the test.
All these study strategies are based on well-established principles of learning and
memory. Studying this way may sound like a lot of work—and it is. But the results will
be worth the mental effort.
Check Your Understanding
1. ANALYSIS: What happens to memory over time, as described by
Ebbinghaus’s forgetting curve?
2. APPLICATION: Which kind of forgetting is involved when the
sociology I studied yesterday makes it more difficult to learn and
remember the psychology I am studying today?
3. RECALL: Describe at least three ways you can apply what you
have learned in this chapter to improve your studying and memory.
4. RECALL: Which of the seven “sins” of memory was responsible for
Piaget’s fabricated memory of an attempted kidnapping?
5. UNDERSTANDING THE CORE CONCEPT: Which of the “sins”
of memory probably helps us avoid dangerous situations we have
encountered before?
Answers 1. We forget rapidly at first and then more slowly as time goes on. 2. Proactive interference 3. Elaborative rehearsal, distributed learning, and
creating a variety of memory cues for each concept. 4. Suggestibility 5. Persistence
Study and Review at MyPsychLab

206 C H A P T E R 5 Memory
A series of studies has revealed striking evidence that children
with an avoidant attachment style—or a general lack of trust in
their environment and the principal people in it (see Chapter 7)—
are less likely to mentally process an abusive event when it oc-
curs, resulting in less likelihood of a memory being encoded and
stored in long-term memory. For these individuals, the end result
may indeed be what has historically been termed “repression.”
Could Bias Contaminate the Conclusion? We have seen
that memory does not make a complete record of our experi-
ences. Nor is it always accurate. Of special relevance to the
recovered memory controversy is research we discussed ear-
lier in the chapter, showing that memories can rather easily
be modified or even created by suggestion. As a result, par-
ticipants not only report false memories but begin to believe
them (Bruck & Ceci, 2004). Such experiments should make
us skeptical of memories recovered during therapy or inter-
rogation involving suggestive techniques. Memory expert
Elizabeth Loftus argues that therapists who assume that most
mental problems stem from childhood sexual abuse com-
monly use suggestive practices, although she does not say how
widespread the problem might be (Loftus, 2003a, b). And in
the book Making Monsters, social psychologist Richard Ofshe
and his coauthor describe how clients can unknowingly tailor
their recollections to fit their therapists’ expectations. He adds
that “therapists often encourage patients to redefine their life
histories based on the new pseudomemories and, by doing so,
redefine their most basic understanding of their families and
themselves” (Ofshe & Watters, 1994, p. 6).
We are not saying that all, or even most, therapists use
suggestive techniques to probe for memories of sexual abuse,
although some certainly do (Poole et al., 1995). Nevertheless,
patients should be wary of therapists who go “fishing” for
repressed memories of early sexual experiences using such
techniques as hypnosis, dream analysis, and suggestive ques-
tioning. No evidence exists in support of these methods for
the recovery of accurate memories.
Another source of suggestion that pops up in a surprisingly
large proportion of recovered memory cases is a book: The
Courage to Heal. This book argues that forgotten memories
of incest and abuse may lie behind people’s feelings of pow-
erlessness, inadequacy, vulnerability, and a long list of other
unpleasant thoughts and emotions (Bass & Davis, 1988). The
authors state, “If you . . . have a feeling that something abusive
happened to you, it probably did” (pp. 21–22). None of these
assertions, however, rests on anything more solid than specula-
tion. Thus, say memory experts Elizabeth Loftus and Kather-
ine Ketcham (1994), it seems likely that The Courage to Heal
has contributed to many false memories of sexual abuse.
CRITICAL THINKING APPLIED
The Recovered Memory Controversy
Let’s return now to the case studies with which we began the chapter. All involved claims of recovered memories: Ross’s
memory of molestation by a camp counselor was clearly ac-
curate, and Donna’s memory of abuse by her father was even-
tually repudiated. So where does that leave us when we hear
about other such claims?
What Are the Critical Issues?
The controversy centers on the accuracy of claims of recovered
memories—not on the reality of sexual abuse. Is it possible that
recovered memories could be false? If so, we must decide how
to judge their accuracy, especially memories of traumatic events.
Is the Claim Reasonable or Extreme? Let’s begin by
asking: Is the notion of recovered memories of sexual abuse
reasonable or outrageous? That is, does it fit with what we
know both about memory and about sexual abuse? Let’s see
what the evidence can tell us.
We need to emphasize that sexual abuse of children
does occur and poses a serious problem. How widespread
is it? While estimates vary considerably, it appears that 4 to
20 percent of children in the United States have experienced
at least one incident of sexual abuse (McAnulty & Burnette,
2004; Terry & Tallon, 2004). Accurate figures are difficult
to obtain, of course, because people can be reluctant to dis-
cuss these experiences. And if it is true that sexual abuse can
be blocked out of consciousness for long periods, the actual
numbers could be higher.
We should also note that most claims of sexual abuse do
not involve “recovered” memories. In general, we have no
reason to doubt people who say they have been molested and
have always remembered. The controversy centers on memo-
ries said to have been “recovered” after having been forgotten
for months or even years.
What Is the Evidence? The general public harbors a
strong but unfounded belief that the most common response
to trauma is repression, the blocking of memories in the un-
conscious, as first described by Sigmund Freud. But, in fact,
most people who have traumatic experiences remember them
vividly, rather than forgetting them (McNally et al., 2003).
Unwelcome remembering of disturbing experiences is pre-
cisely the problem in posttraumatic stress disorder (PTSD).
How, then, can we account for the fact that a portion of cases
in almost every research study in this area includes some re-
ports of repression (Greenhoot et al., 2008)?
Until recently, psychologists were at a loss to answer this
question. But now, University of California psychologist Gail
Goodwin and her colleagues (2010) may have found the answer.

Chapter Summary 207
What Conclusions Can We Draw?
So, where does this leave us? Weigh the evidence yourself on
a case-by-case basis, mindful of the possibility that emotional
biases can affect your thinking. Keep in mind the following
points as well:
• Sexual abuse of children does occur and is more preva-
lent than most professionals suspected just a generation
ago (McAnulty & Burnette, 2004).
• On the other hand, memories cued by suggestion, as from
therapists or police officers, are particularly vulnerable to
distortion and fabrication (Loftus, 2003a). So, without
independent evidence, there is no way to tell whether a
recovered memory is true or false.
• Remember that people can feel just as certain about false
memories as accurate ones.
• Although traumatic events can be forgotten and later re-
called, they are much more likely to form persistent and
intrusive memories that people cannot forget. Neverthe-
less, cases such as that of Ross show us that recovered
memories of abuse can be true.
• Early memories, especially those of incidents that may
have happened in infancy, are likely to be fantasies or
misattributions. As we have seen, episodic memories of
events before age 3 are rare (Schacter, 1996).
• One should be more suspicious of claims for memories
that have been “repressed” and then “recovered” years
later than for memories that have always been available
to consciousness.
We should also note that the issue of recovered memories
is both complex and charged with emotion—a situation ripe
for emotional bias. Not only does the issue of sexual abuse
strike many people close to home, but none of us wants to
turn our back on those who believe they have been victims
of sexual abuse. Yet what we know about memory tells us
that we should not accept long-forgotten traumatic memories
without corroborating evidence.
Does the Reasoning Avoid Common Fallacies? When
we observe associations between things, we have a natural
tendency to suspect that one might cause the other—as we
associate overeating with gaining weight or spending time in
the sun with a sunburn. Most of the time this logic serves us
well, but occasionally it leads us to the wrong conclusions—
as when we conclude that a chill causes a cold or that eating
sweets causes a “sugar high.” Experts call this the post hoc
fallacy: Post hoc literally means “after the fact,” and the idea
is that looking back at events occurring in succession (e.g.,
sugar followed by excitement), we may erroneously conclude
that the first event is the cause of the second.
How could the post hoc fallacy contribute to the “recov-
ered memory” controversy? When people “look back” in
their memories and find a memory (accurate or not) of abuse
that seems to be associated with their current unhappiness,
they assume the abusive event (again, whether real or errone-
ously remembered) is the cause of their current mental state.
But, as we have seen, this conclusion may be faulty. Ironi-
cally, this can reinforce one’s belief in the memory—through
confirmation bias.
FINDING OUT MORE ABOUT ISSUES IN REPORTS OF REPRESSED MEMORIES
In this discussion, you may have noticed
names of two researchers who are espe-
cially prominent in the area memory and
false memories: Elizabeth Loftus and Gail
Goodman. Find a recent article (published
in the past year) by one of these authors,
read it, and identify three main points the
article makes that add to what you learned
in this chapter.
CHAPTER SUMMARY
CHAPTER PROBLEM: How can our knowledge about mem-
ory help us evaluate claims of recovered memories?
• Evidence clearly shows that most people form powerful
memories of traumatic events, rather than repressing them.
• Up to one-third of the population has been demonstrated
by research to be susceptible to relatively easy formation of
false memories. Thus, suggestive questioning techniques by
therapists or other authority figures may inadvertently lead a
person to create false memories that are in accordance with a
therapist’s suggestion.
• People with an avoidant attachment style have been found by
researchers to be more likely to suppress traumatic memories
than people with other attachment styles.
Listen at MyPsychLabto an audio file of your chapter

208 C H A P T E R 5 Memory
5.1 What Is Memory?
Core Concept 5.1 Human memory is an information
processing system that works constructively to encode, store,
and retrieve information.
Human memory, like any memory system, involves three im-
portant tasks: encoding, storage, and retrieval. Although many
people believe that memory makes a complete and accurate
record, cognitive psychologists see human memory as an in-
formation processing system that interprets, distorts, and
reconstructs information. Eidetic imagery, however, is a rare
and poorly understood form of memory that produces espe-
cially vivid and persistent memories that may interfere with
thought. It is not clear how eidetic memory fits with the
widely accepted three-stage model of memory.
eidetic imagery (p. 175)
encoding (p. 174)
information-processing model (p. 174)
memory (p. 172)
retrieval (p. 175)
storage (p. 175)
5.2 How Do We Form Memories?
Core Concept 5.2 Each of the three memory stages
encodes and stores memories in a different way, but they
work together to transform sensory experience into a lasting
record that has a pattern or meaning.
The memory system is composed of three distinct stages: sen-
sory memory, working memory, and long-term memory. The
three stages work together sequentially to convert incoming
sensory information into useful patterns or concepts that can
be stored and retrieved when needed later.
Sensory memory holds 12 to 16 visual items for up to just a
second or two, making use of the sensory pathways. A separate
sensory register for each sense holds material just long enough
for important information to be selected for further processing.
Working memory, which has the smallest storage capacity
of the three stages and a duration of 20 to 30 seconds, draws
information from sensory memory and long-term memory
and processes it consciously. Theorists have proposed at least
four components of working memory: a central executive, a
phonological loop, a sketchpad, and an episodic buffer. We
can cope with its limited duration and capacity by chunking
and rehearsal. The biological basis of working memory is not
clear, but it is believed to involve actively firing nerve circuits,
probably in the frontal cortex.
Long-term memory has apparently unlimited storage
capacity and duration. It has two main partitions, declarative
memory (for facts and events) and procedural memory (for per-
ceptual and motor skills). Declarative memory can be further
divided into episodic memory and semantic memory. Semantic
information is encoded, stored, and retrieved according to
the meaning and context of the material. The case of H. M.
showed that the hippocampus is involved in transferring in-
formation to long-term memory. Other research has found
long-term memories associated with relatively permanent
changes at the synaptic level.
Flashbulb memories are common in highly emotional
experiences. While most people have a great deal of confi-
dence in such vivid memories, studies have shown these
memories are no more accurate than everyday memories.
acoustic encoding (p. 182)
anterograde amnesia (p. 187)
childhood amnesia (p. 186)
chunking (p. 181)
consolidation (p. 188)
declarative memory (p. 184)
elaborative rehearsal (p. 181)
engram (p. 187)
episodic memory (p. 185)
flashbulb memory (p. 189)
levels-of-processing theory (p. 183)
long-term memory (LTM) (p. 177)
maintenance rehearsal (p. 181)
procedural memory (p. 184)
retrograde amnesia (p. 188)
schema (p. 185)
semantic memory (p. 185)
sensory memory (p. 177)
working memory (p. 177)
5.3 How Do We Retrieve Memories?
Core Concept 5.3 Whether memories are implicit or
explicit, successful retrieval depends on how they were
encoded and how they are cued.
H. M.’s case also demonstrated that information can be stored
as explicit or implicit memories. The success of a memory search
depends, in part, on the retrieval cues. Implicit memories can
be cued by priming. Explicit memories can be cued by vari-
ous recall or recognition tasks, although some tasks require
remembering the gist rather than exact details. The accuracy
of memory retrieval also depends on encoding specificity and
mood. Relatively little is known about the conditions required
for successful prospective memory. When there is a poor match
between retrieval cues and the encoding, we may experience
the TOT phenomenon.

encoding specificity principle (p. 193)
explicit memory (p. 191)
gist (p. 192)
implicit memory (p. 191)
mood-congruent memory (p. 193)
priming (p. 192)
prospective memory (p. 194)
recall (p. 192)
recognition (p. 193)
retrieval cue (p. 191)
TOT phenomenon (p. 194)
5.4 Why Does Memory Sometimes Fail Us?
Core Concept 5.4 Most of our memory problems arise
from memory’s “seven sins”—which are really by-products
of otherwise adaptive features of human memory.
Memory failures involve the “seven sins” of memory. These
include forgetting, resulting from weakening memory traces
(transience), lapses of attention (absent-mindedness), and inabil-
ity to retrieve a memory (blocking). Some forgetting can be at-
tributed to a cause of transience known as interference. Memory
can also fail when recollections are altered through misattribution,
suggestibility, and bias. An important example involves eyewitness
memories, which are subject to distortion. Suggestibility can also
produce false memories that seem believable to the rememberer.
The final “sin” of persistence occurs when unwanted memories
linger in memory even when we would like to forget them.
The “seven sins” of memory, however, are by-products
of a memory system that is well suited to solving problems
of day-to-day living. Some of these problems can be over-
come by mnemonic strategies, such as the method of loci, natural
language mediators, and other associative methods. The learn-
ing of concepts, however, requires special strategies geared
to learning the gist of the material and to avoiding the two
memory “sins” of transience and blocking.
absent-mindedness (p. 198)
blocking (p. 198)
distributed learning (p. 204)
expectancy bias (p. 202)
forgetting curve (p. 196)
method of loci (p. 203)
misattribution (p. 199)
misinformation effect (p. 200)
mnemonic strategy (p. 203)
natural language mediator (p. 203)
persistence (p. 202)
proactive interference (p. 197)
retroactive interference (p. 197)
self-consistency bias (p. 202)
serial position effect (p. 197)
suggestibility (p. 200)
transience (p. 196)
whole method (p. 204)
CRITICAL THINKING APPLIED
The Recovered Memory Controversy
not only do most people NOT repress traumatic memories,
suggestive techniques can actually enable creation of false
memories.
Most people mistakenly believe that traumatic memories are
subject to repression and can later be recovered accurately
through hypnosis or other techniques. Evidence indicates that
Chapter Summary 209

210 C H A P T E R 5 Memory
7. According to Sigmund Freud, what is the purpose of
repression?
a. to protect the memory from encoding too much material
b. to preserve the individual’s self-esteem
c. to activate networks of associations
d. to fit new information into existing schemas
8. In an experiment, people spent a few minutes in an office. They
were then asked to recall what they had seen. They were most
likely to recall objects that
a. fit into their existing schema of an office.
b. carried little emotional content.
c. were unusual within that particular context.
d. related to objects they owned themselves.
9. The paintings Franco Magnani made of an Italian town were
distorted mainly by
a. repression, causing some features to be left out.
b. a child’s perspective.
c. sensory gating, changing colors.
d. false memories of items that were not really there.
10. What was Karl Lashley’s goal in teaching rats how to negotiate
mazes and then removing part of their cortexes?
a. finding out how much tissue was necessary for learning
to occur
b. determining whether memory was localized in one area of
the brain
c. discovering how much tissue loss led to
memory loss
d. finding out whether conditioned responses could be
eradicated
11. What has Richard Thompson found in his work with rabbits
conditioned to a tone before an air puff?
a. Rabbits learn the response more slowly after
lesioning.
b. Eyelid conditioning involves several brain areas.
c. The memory of the response can be removed by lesioning.
d. Once the response is learned, the memory is permanent,
despite lesioning.
Program Review
1. What pattern of remembering emerged in Hermann Ebbinghaus’s
research?
a. Loss occurred at a steady rate.
b. A small initial loss was followed by no further loss.
c. There was no initial loss, but then there was a gradual decline.
d. A sharp initial loss was followed by a gradual decline.
2. The way psychologists thought about and studied memory was
changed by the invention of
a. television.
b. electroconvulsive shock therapy.
c. the computer.
d. the electron microscope.
3. What do we mean when we say that memories must be encoded?
a. They must be taken from storage to be used.
b. They must be put in a form the brain can register.
c. They must be transferred from one network to another.
d. They must be put in a passive storehouse.
4. About how many items can be held in short-term memory?
a. three
b. seven
c. 11
d. an unlimited number
5. Imagine you had a string of 20 one-digit numbers to remember.
The best way to accomplish the task, which requires increasing
the capacity of short-term memory, is through the technique of
a. selective attention.
b. peg words.
c. rehearsing.
d. chunking.
6. According to Gordon Bower, what is an important feature of good
mnemonic systems?
a. There is a dovetailing between storage and retrieval.
b. The acoustic element is more important than the visual.
c. The learner is strongly motivated to remember.
d. Short-term memory is bypassed in favor of long-term
memory.
Watch the following video by logging into MyPsychLab (www.mypsychlab.com).
After you have watched the video, answer the questions that follow.
PROGRAM 9: REMEMBERING
AND FORGETTING
DISCOVERING PSYCHOLOGY VIEWING GUIDE

www.mypsychlab.com

Discovering Psychology Viewing Guide 211
12. Patients with Alzheimer’s disease find it almost impossible to
produce
a. unconditioned responses.
b. conditioned stimuli.
c. conditioned responses.
d. unconditioned stimuli.
13. The best way to keep items in short-term memory for an indefinite
length of time is to
a. chunk.
b. create context dependence.
c. use the peg-word system.
d. rehearse.
14. Long-term memory is organized as a
a. complex network of associations.
b. serial list.
c. set of visual images.
d. jumble of individual memories with no clear organizational
scheme.
15. You remember a list of unrelated words by associating them, one
at a time, with images of a bun, a shoe, a tree, a door, a hive,
sticks, Heaven, a gate, a line, and a hen. What mnemonic
technique are you using?
a. method of loci
b. peg-word
c. link
d. digit conversion
16. What did Karl Lashley conclude about the engram?
a. It is localized in the brain stem.
b. It is localized in the right hemisphere only.
c. It is localized in the left hemisphere only.
d. Complex memories cannot be pinpointed within
the brain.
17. Long-term memories appear to be stored in the
a. cortex. c. hippocampus.
b. occipital lobe. d. parietal lobe.
18. How has Diana Woodruff-Pak utilized Richard Thompson’s work
on eyeblink conditioning?
a. as a precursor to early-onset dementia
b. as a predictor of musical genius
c. as a mechanism for growing brain cells in
intact animals
d. as a tool for training long-term visual memories
19. Which neurotransmitter(s) is/are disrupted in Alzheimer’s
patients?
a. scopolamine
b. acetylcholine
c. both of the above
d. none of the above
20. Alzheimer’s disease is associated with the loss of
a. memory. c. life itself.
b. personality. d. all of the above.

6.1 What Are the Components of
Thought?
Concepts
Imagery and Cognitive Maps
Thought and the Brain
Intuition

Key Questions/
Chapter Outline
Thinking and Intelligence6
Psychology Matters
Thinking is a cognitive process in
which the brain uses information from
the senses, emotions, and memory
to create and manipulate mental
representations, such as concepts,
images, schemas, and scripts.
Schemas and Scripts Help You
Know What to Expect
But sometimes they fill in the
blanks—without your realizing it.
6.2 What Abilities Do Good Thinkers
Possess?
Problem Solving
Judging and Making Decisions
Becoming a Creative Genius
Good thinkers not only have a
repertoire of effective strategies,
called algorithms and heuristics, they
also know how to avoid the common
impediments to problem solving and
decision making.
Using Psychology to Learn
Psychology
Psychologists have learned the secrets
of developing expertise—in psychology
or any other subject.
Intelligence testing has a history of
controversy, but most psychologists
now view intelligence as normally
distributed and measurable by
performance on a variety of tasks.
What Can You Do for an
Exceptional Child?
In both mental retardation and
giftedness, children should be
encouraged to capitalize on their
abilities.
6.3 How Is Intelligence Measured?
Binet and Simon Invent a School Abilities Test
American Psychologists Borrow Binet and
Simon’s Idea
Problems with the IQ Formula
Calculating IQs “on the Curve”
IQ Testing Today
6.4 Is Intelligence One or Many
Abilities?
Psychometric Theories of Intelligence
Cognitive Theories of Intelligence
Cultural Definitions of Intelligence
The Question of Animal Intelligence
Some psychologists believe that
intelligence comprises one general
factor, g, while others believe that
intelligence is a collection of distinct
abilities.
Test Scores and the
Self-Fulfilling Prophecy
An IQ score can create expectations
that develop a life of their own.
6.5 How Do Psychologists Explain IQ
Differences Among Groups?
Intelligence and the Politics of Immigration
What Evidence Shows That Intelligence Is
Influenced by Heredity?
What Evidence Shows That Intelligence Is
Influenced by Environment?
Heritability (not Heredity) and Group
Differences
While most psychologists agree that
both heredity and environment affect
intelligence, they disagree on the
source of IQ differences among racial
and social groups.
Stereotype Threat
A simple reminder that you belong to a
minority group may be enough to lower
your test scores.
CHAPTER PROBLEM What produces “genius,” and to what extent are the people we call
“geniuses” different from others?
CRITICAL THINKING APPLIED The Question of Gender Differences
Core Concepts

213
F OLLOW YOUR PASSIONS AND YOU, TOO, MAY BECOME A MULTIMILLIONAIRE. At least that’s what happened to Sergey Brin and Larry Page, graduate students in computer science at Stanford University. Both were deeply interested in finding a quicker way to search the Internet and extract specific information from its abun-
dance of informational riches.
It was January of 1996, and both Brin and Page had some creative ideas about how to
search the Web more efficiently than existing search engines could. After combining forces, the
first thing this duo did was to build a computer in Larry’s dorm room, equipping it with as much
memory as they could afford.
The first-generation search engine to come out of their collaboration was BackRub, so called
because it could identify and follow “back links” to discover which websites were listing a par-
ticular page—giving them an index of how valuable users had found a site to be. And, while their
search engine performed well, Brin and Page couldn’t get any of the big computer companies or
existing Internet entrepreneurs to buy their design. So they started their own business—with a little
financial help from their family and friends. One friend of a Stanford faculty member saw so much
promise in their enterprise that he wrote them a check for $100,000. The check sat in a drawer
in Page’s desk for two weeks because they hadn’t yet set up a company that could cash the check.
In most respects, Brin and Page’s search engine worked like any other Web-searching soft-
ware. It sent out electronic “spiders” that crawl across Web pages, looking for important terms
and listing them in an index, along with their Web addresses. It also followed links on the Web
pages it scanned (both forward and backward) and listed more terms. The secret ingredient
for their success remains as closely guarded as the formula for Coca-Cola. It involves the way
results are ranked for presentation to the user. More often than not, it manages to put the sites

214 C H A P T E R 6 Thinking and Intelligence
computer metaphor The idea that the brain
is an information-processing organ that operates, in
some ways, like a computer.
users want most near the top of a list that can include millions of possible sources. Thus, the
software is designed to serve as the link between a concept in the user’s mind and billions of
words on the Web. In other words, Brin and Page had to organize their search engine to “think”
as much as possible like a person—which is what this chapter is about.
The public seemed to like their search engine. In fact, the public liked it far better than
did the big companies that had turned it down. And over the next decade, it became “the little
engine that could.” First, it outgrew Page’s dorm room and—in the great tradition of American
inventors and rock bands—into a garage. Today, it has offices spread throughout the United
States and 36 other countries, with more than 20,000 employees. It also has a reputation
as the most comprehensive of search engines, indexing key words from billions of Web pages.
Every day, it processes hundreds of millions of search requests. Things got so busy that Brin and
Page had to take a leave from graduate school to run the company—which they renamed after
the term mathematicians use for the number 1 followed by 100 zeros. They called it Google.
In some respects, Brin and Page are like other legendary pioneers in the computer field:
the two Steves, Jobs and Wozniak, who started Apple Computers in a garage, and Bill Gates
who, with his friend Paul Allen, launched Microsoft on a shoestring. All could be called
“geniuses,” a term that frames our initial problem for this chapter:
PROBLEM: What produces “genius,” and to what extent are the people we call
“geniuses” different from others?
As we consider this problem, here are some additional questions worth pondering:
• Thomas Edison once said that genius is 1 percent inspiration, 99 percent perspiration. If
so, does that mean genius is mainly a matter of high motivation rather than aptitude or
talent?
• Is genius a product mainly of nature or of nurture?
• Do geniuses think differently from the rest of us? Or do they just use the same thought
processes more effectively?
• Could Einstein (for example), whose specialty was physics, have been a genius in painting
or literature or medicine if he had chosen to do so? That is, are there different kinds of
genius? And is the potential for genius specific to a particular field?
We will address all these questions in the following pages. But first, let’s return to Google and
the computer metaphor for the human mind, as we begin our inquiry into thinking and intelligence.
Despite its phenomenal success, Google is only a pale imitation of the human mind.
Sure, it can scan its memory, amassed from up to one trillion Web pages, and return
over one billion links on, say, the term “search engine” in about a half second. But ask
it what food to serve at a birthday party, and it will merely serve up (at this writing)
49,800,000 links to the terms “birthday” and “party” and “food.” Unlike most human
minds, Google and its network of supportive hardware is clueless. So is the computer
on your desk. Computers just don’t index information by meaning.
Nevertheless, computers in the hands of cognitive scientists can be powerful tools
for studying how we think—for three reasons. First, these scientists use computers in brain
imaging studies, which have shown the brain to be a system of interrelated processing
modules, as we have seen. Second, researchers use computer simulations that attempt
to model human thought processes. And third, while they haven’t yet made a computer
function exactly like a brain, cognitive scientists have adopted the computer as a meta-
phor for the brain, as a processor of information.
This computer metaphor—the brain as an information processor—suggests that thinking
is nothing more, or less, than information processing. The information we use in thought
can come from raw data we receive from our senses, but it can also come from meaningful

What Are the Components of Thought? 215
concepts in long-term memory. As you can see, then, the
psychology of thinking deals with the same processes we
discussed in connection with learning and memory.
To be sure, the computer metaphor is not perfect. Com-
puters can’t deal with meaning. And, as we will see, they
are not very good at abstract thought or humor (although
they are very good at transmitting the millions of jokes
shared on e-mail each day). Consequently, some psycholo-
gists encourage moving beyond the computer metaphor to
talk about the sort of modular, parallel information pro-
cessing that we now know the brain really does when it
thinks. Evolutionary psychologists, for example, suggest
the brain is more like a Swiss Army knife—an all-purpose
tool that can adapt to many uses, with a variety of special-
ized components for particular functions. Nevertheless, the
computer metaphor is a good place to begin our thinking
about thought.
In the first two sections of this chapter, we will focus
on the processes underlying thought, especially in decision making and problem solving.
This discussion will examine the building blocks of thought: concepts, images, schemas,
and scripts. Our excursion into thinking will also give us the opportunity to return for a
closer look at that mysterious quality known as “genius.”
In the second half of the chapter, we will turn to the form of thinking we call intel-
ligence. There you will learn about IQ tests, conflicting perspectives on what intelligence
really is, and what it means to say that IQ is “heritable.” In the Using Psychology to
Learn Psychology feature, you will learn how to apply the knowledge in this chapter
to become an expert in psychology—or any other field you choose. Finally, our Critical
Thinking Application will look at the controversial issue of gender differences in thought.
6.1 KEY QUESTION
What Are the Components of Thought?
Solving a math problem, deciding what to do Friday night, and indulging a private
fantasy all require thinking. We can conceive of thinking as a complex act of cog-
nition—information processing in the brain—by which we deal with our world of
ideas, feelings, desires, and experience. Our Core Concept notes that this information
can come from within and from without, but it always involves some form of mental
representation:
Core Concept 6.1
Thinking is a cognitive process in which the brain uses information
from the senses, emotions, and memory to create and manipulate
mental representations such as concepts, images, schemas, and
scripts.
These mental representations, then, serve as the building blocks of cognition, while
thinking organizes them in meaningful ways. The ultimate results are the higher
thought processes we call reasoning, imagining, judging, deciding, problem solving,
expertise, creativity, and—sometimes—genius.
Concepts
Have you ever visited a new place only to feel like you had been there before? Or had
a conversation with someone and felt the experience was uncannily familiar? If so,
you have experienced a phenomenon known as déjà vu (from the French for “seen
The cognitive perspective focuses on
mental processes as the primary key to
human behavior.
Watson, an IBM computer capable of
responding to human language, bested
two top-winning Jeopardy contestants in
2011. While this technology is a great
leap forward in artificial intelligence, crit-
ics argue that rapid computational skills
should not be confused with a true under-
standing of meaning.

216 C H A P T E R 6 Thinking and Intelligence
before”). The term refers to the strange sense that your present experience matches a
previous experience, even though you cannot retrieve the explicit memory. This feeling
reflects the brain’s ability to treat new stimuli as instances of familiar categories, even
if the stimuli are slightly different from anything it has encountered before. Why is
that important? Imagine what life would be like if, every time we started a new class in
school, for example, we couldn’t access any of our previous school experiences, so we
had to start from scratch to figure out what to do, how to study, and what the point
of school even was. This ability to assimilate experiences, objects, or ideas into famil-
iar mental categories—and take the same action toward them or give them the same
label—is one of the most basic attributes of thinking organisms (Mervis & Rosch,
1981).
The mental categories we form in this way are known as concepts. We use them as
the building blocks of thinking because they help us organize our knowledge (Goldman-
Rakic, 1992). Concepts can represent classes of objects such as “chair” or “food,” living
organisms such as “birds” or “buffaloes,” or events like “birthday parties.” They may
also represent properties (such as “red” or “large”), abstractions (such as “truth” or
“love”), relations (such as “smarter than”), procedures (such as how to tie your shoes),
or intentions (such as the intention to break into a conversation) (Smith & Medin,
1981). But because concepts are mental structures, we cannot observe them directly.
For the cognitive scientist, this means inferring concepts from their influence on behav-
ior or on brain activity. For example, you cannot be sure another person shares your
concept of “fun,” but you can observe whether he or she responds the same way you
do to stimuli you interpret as “fun.”
Two Kinds of Concepts Everyone conceptualizes the world in a unique way, so
our concepts define who we are. Yet, behind this individual uniqueness lie similarities
in the ways we all form concepts. In particular, we all distinguish between natural
concepts and artificial concepts (Medin et al., 2000).
Natural concepts are imprecise mental categories that develop out of our everyday
experiences in the world. You possess a natural concept of “bird” based on your ex-
periences with birds, which in turn invokes a mental prototype, a generic image rep-
resenting a typical bird from your experience (Hunt, 1989). To determine whether
an object is a bird or not, you mentally compare it to your bird prototype—and the
closer it matches, the quicker you can make your decision. Most people take less time
to recognize an eagle as a bird than a penguin, for example (Rips, 1997). Our personal
prototypes encompass all kinds of natural concepts, including friendship, intimacy,
and sex. And, for all these, one person’s prototype might differ from that of someone
else, which can create the basis for misunderstanding in our relationships. Natural
concepts are sometimes called “fuzzy concepts” because of their imprecision (Kosko &
Isaka, 1993).
By comparison, artificial concepts are defined by a set of rules or characteristics, such
as dictionary definitions or mathematical formulas. The definition of “rectangle” is an
example. Artificial concepts represent precisely defined ideas or abstractions rather
than actual objects in the world. So, if you are a zoology major, you may also have an
artificial concept of “bird,” which defines it as a “feathered biped.” In fact, most of the
concepts you learn in school are artificial concepts—such as “cognitive psychology,”
and even the concept of “concept”!
Concept Hierarchies We organize much of our declarative memory into concept
hierarchies, arranged from general to specific, as illustrated in Figure 6.1. For most
people, the broad category of “animal” has several subcategories, such as “bird” and
“fish,” which are divided, in turn, into specific forms, such as “canary,” “ostrich,”
“shark,” and “salmon.” The “animal” category may itself be a subcategory of the still
larger category of “living beings.” Also, we can often link each category to a variety of
other concepts: For example, some birds are edible, some are endangered, and some
are national symbols. In this way, our concept hierarchies are often intricate webs of
concepts and associations.
concepts Mental groupings of similar objects,
ideas, or experiences.
natural concepts Mental representations of
objects and events drawn from our direct experience.
prototype An ideal or most representative example
of a conceptual category.
artificial concepts Concepts defined by rules,
such as word definitions and mathematical formulas.
concept hierarchies Levels of concepts, from
most general to most specific, in which a more general
level includes more specific concepts—as the concept
of “animal” includes “dog,” “giraffe,” and “butterfly.”
Your natural concept of “bird” involves
a prototype that is probably more like an
eagle than a penguin. Hence, you would
likely classify an eagle as a bird faster than
you would a penguin. Biology majors, how-
ever, may also have an artificial concept of
“bird” that works equally well for both.

What Are the Components of Thought? 217
Culture, Concepts, and Thought Concepts can carry vastly different meanings in
different cultures. For example, the concepts of “democracy” and “freedom,” so dear
to Americans, may have the connotation of chaos, excess, and rudeness in parts of Asia
and the Middle East.
Americans also differ from many Asians in the ways they deal with conflicting ideas
and contradictions (Peng & Nisbett, 1999). We can see this in the way the Chinese
have dealt with the conflicting ideologies of capitalism and communism by allowing
elements of both to flourish in their economy, an approach many Americans find diffi-
cult to understand. The Chinese culture encourages thinkers to keep opposing perspec-
tives in mind and seek a “middle way,” while American culture tends toward thinking
in more polarized “either-or” terms—capitalism or communism.
Another big cu