1
Some Basic Assumptions
Learning Objectives
After reading this chapter, you should be able to do the following:
• Analyze the claim that our behavior is determined by our heredity and environment, citing evidence for the role of our brains in controlling behavior and examples of how the environment
can influence behaviors.
• Explain the two main methods that have been proposed to study the laws of learning: introspection and experiments.
• Explain the importance of manipulating only one independent variable at a time in an experiment, and how this can result in experiments seeming artificial and progress being slow.
• Contrast behavioral and cognitive approaches to whether psychologists should study the role
of the mind in determining behavior.
• Explain the seeming paradox of why psychologists, whose goal is to understand human behavior, have often studied animals instead, and discuss the ethical issues raised by using animals
in research.
• Define learning and, in particular, a subcategory called associative learning, and explain the
forms of associative learning that we will focus on here, classical and operant conditioning.
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Chapter 1: Some Basic Assumptions
CHAPTER 1
As you already know from the title, this textbook will be about learning, which we can
define as our capacity to change our behavior based on experience. We’ll be focusing on
three particular kinds of learning: classical conditioning, reinforcement, and punishment.
(We’ll define all three later.) For each one, we’ll try to understand the basic processes
involved, but we’ll also be looking at some important practical questions. If you want to
encourage a boy to study, for example, should you offer him a reward for good grades?
If the answer is yes, what kind of reward would be most effective? Conversely, if you
wanted to stop a girl from stealing, should you punish her when she does so?
Psychologists have been studying questions like these for more than a century, but you’ll
discover throughout this text that they still disagree, sometimes vehemently, about the
answers. Why? Why should it be so difficult to discover the facts about learning? Or, even
more fundamentally, what is a fact?
Of course everyone knows what a fact is; it’s something that everyone knows to be true.
Or is it? Was it a fact that the earth was flat because everyone before Columbus believed
it to be so? Or that the earth was the center of the universe before Copernicus and Galileo
moved it into orbit around the sun? If we cannot be sure of the truth in cases as seemingly
obvious as these, how much more difficult must it be when the truth is more obscure, and
when experts can’t agree among themselves? If one “scientist” claims that the moon is
composed of blue cheese, and another that it is clearly a brownie, how are we to decide
which of their views is correct?
In older sciences, such as physics and chemistry, disputes over scientific facts are less obvious. Over the years, basic concepts such as the existence of the atom and the law of gravity
have become firmly established. Only after considerable training are new initiates to the
profession gradually introduced to the ambiguities and uncertainties of current research.
In psychology, which is a relatively new science, the dividing line between “old established facts” and “new controversial hypotheses” is less clear, and there is no comforting
bedrock of certainty and accomplishment to support students feeling overwhelmed by
conflicting claims. Consider the use of corporal punishment: Is it an effective and ultimately humane way to eliminate a child’s harmful behavior, or is it a relic of our primitive
past? There is evidence to support both views, and it can be more than a little frustrating
to try to analyze the arguments of each side.
In their attempts to resolve such disagreements—to decide what is a fact and what is not—
psychologists have relied on several assumptions. These assumptions are now so widely
accepted that psychologists rarely question them, but this does not necessarily mean that
they are correct. It is perhaps worth emphasizing in advance that the assumptions we will
examine in this chapter really are assumptions and are not universally accepted, even
among psychologists. You should approach them with a healthy skepticism and form
your own views as to their validity. The better you understand these assumptions, however, the better you will understand why research has followed the paths that we will
trace in subsequent chapters.
One purpose of this chapter, then, is to examine the methodological assumptions that
have guided psychological research: why psychologists rely on experiments to understand behavior, and the logic that guides researchers in designing these experiments.
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Section 1.1 Is Behavior Lawful?
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Before considering how to do research, however, we will begin by focusing on an even
more fundamental issue: Why study behavior in the first place?
1.1 Is Behavior Lawful?
The most fundamental assumption underlying research into the laws of learning is that
there are such laws—if behavior were random, there would be little point in trying to discover the laws that govern it. To clarify the issue, let us begin by defining more precisely
what we mean by a law. Within science, a law is essentially a statement of the form “If A,
then B.” That is, if some condition A exists, we predict that event B will occur. The statement
“The sun rises every morning,” for example, predicts that if it is morning, then the sun will
rise. The assertion that behavior is lawful, therefore, is essentially a claim that behavior is
in principle predictable: The same set of conditions will always produce the same behavior.
Determinism Versus Free Will
Most of us believe that at least some aspects of behavior are predictable. However much
we might dislike some powerful bully, for example, we don’t usually walk over to him
and punch him in the nose, because we know very well that his reaction will not be random but intensely and unpleasantly predictable. Opinion varies, however, as to the extent
of this predictability.
Determinism
At one extreme, some believe that all behavior is predictable. According to the doctrine of
determinism, human behavior is entirely dictated by heredity and environment (as used
here, the word “environment”
refers to past experiences as
well as present environment).
Your decision to go to college,
for example, was probably influenced by factors such as the educational background of your parents, the grades you received at
school, the economic advantages
of a degree, and so forth. According to determinism, these factors
made it inevitable that you would
eventually choose to go to college,
whether or not you were consciously aware of their influence.
Dramatic advances in physics
and chemistry have accustomed
us to the idea that nature is inherently orderly, even though our
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The orbit of the moon is an example of an outcome that’s
determined by a set law of physics. It always follows the
same path, according to a precise law of nature. Determinists
believe that behavior is also fully lawful, shaped by our
environment and heredity.
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Section 1.1 Is Behavior Lawful?
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ignorance sometimes makes it appear random. But is the behavior of a living organism
just as lawful, just as determined, as the orbit of the moon or the boiling point of water? Are
we really just pawns in the grasp of environmental and genetic forces beyond our control?
Free Will
Within Western civilization, strict determinism has generally been rejected. In this view,
humans are fundamentally free: We all have the power to determine our actions. This free
will makes each of us responsible for our behavior and provides the basis for our concepts
of morality and responsibility. Aside from some formal religious teachings, most of us
resist the idea that we are only insignificant links within a causal chain. We are decidedly
not like billiard balls hurtling through space, propelled by forces we cannot resist.
Why, then, do many research psychologists still believe in determinism? The reasons are
complex, and in the following sections we will consider some of them. As you read this
material, some of the arguments might strike you as more philosophical than psychological, and you might wonder why a psychology textbook devotes so much attention to
this issue. The answer is that a belief in determinism plays an important role in guiding
psychological research. If you
carry out a study to find a lawful relationship and your effort
fails, you are much more likely
to persist in the effort if you are
convinced that such laws really
exist. As a result, many of the
most crucial discoveries about
learning and memory have been
made by psychologists with a
stubborn, even fanatical, belief
that behavior is lawful. (See,
for example, the discussions of
Pavlov in Chapter 2 and Ebbinghaus in Chapter 8.) In the
sections that follow, we will conThe doctrine of free will says that when offered a choice,
sider some arguments that have
we can select whichever option we want, unconstrained by
led to this belief.
external forces.
Neural Determinism
One line of evidence supporting the determinist view comes from our growing understanding of the brain’s role in determining behavior. We will discuss the mechanisms involved
in more detail in Chapter 2, but in essence the brain consists of a vast network of interconnected cells called neurons, and the transmission of electrical signals through these cells
determines our behavior. When we see a friend, for example, the light falling on receptors
located at the back of the eye produces electrical signals, and these are transmitted by a series
of neurons to the cortex (a region of the brain) and ultimately to the muscles that cause us
to raise our hand in greeting or to move our lips to say hello. If physicists are correct, and
the behavior of all particles in the universe is lawful, then the transmission of these electrical impulses through our brain must also be lawful. (Indeed, neurophysiologists already
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Section 1.1 Is Behavior Lawful?
have a good understanding of
the chemical processes that govern the transmission of electrical signals through neurons,
and how the arrival of a signal
at a neuron’s terminal leads to
the release of chemicals, which
then activate the next neuron
in the chain.) If these assumptions are correct—if our brains
control our behavior, and if the
brain’s operations are lawful—
then it logically follows that our
behavior must also be lawful. If
the operation of any system is
lawful, then the output of that
system must also be lawful.
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According to neural determinism, the transmission of electrical
signals through nerve cells in the brain determines our behavior.
We will call this argument neural determinism. Its first assumption—that the firing of
neurons is governed by laws of physics and chemistry that govern all other materials—is
widely accepted, at least within science. The second assumption, though—that our brains
control all aspects of our behavior—is more controversial. We will therefore focus on this
second assumption, examining the brain’s role in three fundamental aspects of behavior:
movement, emotion, and thought.
Movement
Our physical movements are controlled by the transmission of electrical impulses though
our neurons. When we move an arm, for example, the movement is caused by the contraction of muscles within the arm, which are in turn controlled by neurons. Neurons are
connected to every muscle in the body, and electrical impulses arriving at the terminals of
these neurons trigger the release of chemicals that initiate muscular contractions. If these
neural connections are damaged—for example, if the spine is damaged in an automobile
accident so that neural messages can no longer be transmitted from the brain to certain
muscles—we lose the ability to control those muscles. Similarly, the tremors seen in Parkinson’s disease are due to degeneration of neurons in one of the regions of the brain
that helps control movement. Administering a drug that restores the functioning of the
affected neurons can help treat Parkinson’s. This type of evidence illustrates the point that
movement is controlled by the nervous system.
Emotion
In a similar way, our emotions are controlled by specific regions of our brains that are
active. One early experiment demonstrating the brain’s role in emotions was reported
by James Olds and Peter Milner (1954), who found that delivering a tiny electrical current to certain areas of a rat’s brain seemed to produce pleasurable sensations in the rat,
as the rat would press a lever as often as 2,000 times per hour to turn on the current. A
neurosurgeon, Dr. Robert Galbraith Heath (1963), reported similar effects in humans.
One of his patients suffered from narcolepsy, a debilitating condition in which sufferers
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fall asleep at inappropriate times, such as in the middle of a conversation. In an effort to
help this patient stay awake, Heath and his colleagues implanted small electrodes into
several areas of the patient’s brain. They provided the patient with a control panel that
he could use to stimulate these areas. He described one of the buttons on this panel as
his “happy button,” saying it gave him a drunk feeling, and another stimulated sexual
arousal. Heath also described an episode in which the experimenter initiated stimulation while a patient was exhibiting agitated violent psychotic behavior. The effect was
dramatic: “Almost instantly his behavioral state changed from one of disorganization,
rage, and persecution to one of happiness and mild euphoria. . .He was unable, when
questioned directly, to explain the sudden shift to his thoughts and feelings.” (Heath,
1963, p. 575)
Drugs such as alcohol, heroin, and Ecstasy work in a similar way, although usually not
quite so dramatically. By altering chemical activity in the brain, they can profoundly
change the emotions we experience.
Thought
The suggestion that our brains also control what we think is perhaps the most controversial of these claims. Early evidence for the brain’s role in thought came from studies
of epilepsy reported by a Canadian neurosurgeon, Wilder Penfield. Epileptic seizures
are triggered by abnormal activity in one small region of the brain, and in severe cases
it is important to identify the precise region involved so that it can be removed. One
way to do this is to remove part of the skull and use electrodes to stimulate various
parts of the brain while the patient is conscious; the patient can then report when he or
she experiences the sensations that normally precede the seizures, so that the surgeon
can remove the region that produces these feelings. (This technique might sound gruesome, but the scalp is anesthetized first, and because there are no pain receptors in the
brain, the patient suffers no discomfort.) Penfield discovered that stimulation of some
areas would give rise to specific thoughts or images. Depending on the area stimulated,
patients reported hearing someone calling their name, feeling like they were waiting
at a station for a train, or hearing music. If the stimulation was stopped, the sensation
would cease, but it would often return if the same spot was stimulated again (Penfield, 1958). Activity in particular cortical areas thus seemed to control what thoughts a
patient experienced.
For many years Penfield’s findings stood almost alone, as few psychologists had the surgical skills, or the access to patients, to repeat his studies. More recently, though, a variety
of techniques has been developed to monitor brain activity without surgical intervention,
and this emerging research has confirmed Penfield’s findings. One example comes from
a recent study by Sheth, Sandkühler, and Bhattacharya (2009). They gave participants
difficult problems to solve, and asked them to press a key the instant they thought of
the solution. The experimenters used EEG recordings to monitor activity in participants’
brains as they worked. (EEG stands for electroencephalogram; in which electrodes placed
on the scalp record electrical activity occurring inside the brain.) The recordings revealed
that activity in certain areas of the brain preceded solution—the heightened activity was
only observed shortly before solution. This finding was particularly striking because the
electrical activity was observed up to eight seconds prior to the moment when participants
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became consciously aware of the solution. As in Penfield’s studies, conscious experience
seemed to be the product of preceding neural activity.
In summary, it appears as if every aspect of our behavior—movement, emotion, and
thought—depends on the transmission of electrical impulses within our brains. If this
neural activity is lawful, then the behavior that it controls must also be lawful.
Examples of Lawful Behavior
The neural determinism argument claims that behavior must be lawful, but that is not
quite the same as proving that behavior is lawful. There is considerable evidence that our
heredity and environment can strongly influence our behavior, and we will look now at
three examples.
Obedience
Our first example comes from Stanley Milgram’s classic research on obedience (Milgram,
1963, 1974). Milgram was horrified by the behavior of German soldiers who participated
in the murder of millions of people in concentration camps during World War II. Though
some of those involved may have been evil, many seemed to be ordinary soldiers obeying
orders, no matter how vile those orders were.
Milgram designed an experiment that he hoped would allow him to study obedience
in the laboratory. He told participants that he was studying the effects of peer-delivered
punishment on learning. Their task was to administer an electric shock to a partner whenever the partner made an error on a memory problem. The intensity of the shock was
controlled by a series of 30 switches, ranging from 15 to 450 volts, and the experimenter
instructed subjects to increase the intensity of the shock after every error by the partner,
who was in an adjoining room. (Unknown to the subject, the partner was actually in on
the experiment and never received any shocks, but just acted as if they occurred.)
Milgram had hoped to use the highest shock intensity his subjects were willing to administer as a measure of their obedience to authority—in this case, a scientist in a white lab
coat. The astonishing result, which Milgram had not anticipated, was that there were
essentially no limits to his subjects’ obedience. Sixty-five percent continued to administer
shocks even when their partners pounded on the wall and refused to answer any questions and when the switch on the shock control panel was labeled “450 volts . . . Danger:
Severe Shock.” His subjects became extremely upset as the experiment continued, some
laughing hysterically and pleading with the experimenter to let them stop, but almost all
continued to administer shocks when ordered to do so.
Was the extraordinary behavior of the participants in Milgram’s study a product of the
experiment’s artificial conditions and thus atypical (Baumrind, 1964)? The behavior of
German soldiers during World War II argues against this view.
Another poignant example comes from the Vietnam War in the 1960s. In one of the most
notorious incidents of that war, a group of American soldiers entered a small Vietnam
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Section 1.1 Is Behavior Lawful?
village, My Lai, in search of enemy soldiers.
When the American soldiers failed to find the
enemy, they obeyed the orders of their officers
and slaughtered everyone in the village, killing
hundreds of defenseless women and children.
Although the terrible conditions of war undoubtedly played a major role in producing such behavior, Milgram’s research suggests that obedience
is not confined to such situations. We are more
sensitive to social control—to the opinions of our
parents, our friends, even our neighbors—than
we sometimes realize (see also Cialdini, 1993).
Child Abuse
A further example of how powerfully our environment can influence our behavior comes from
studies of children who are physically or sexually
abused. Approximately two thirds of children
who are abused develop serious symptoms, rangThe 1968 My Lai massacre, in which several ing from anxiety and bed-wetting to depression
hundred Vietnamese civilians were killed, is and self-destructive behavior (Kendall-Tackett,
an example of individuals obeying authority Williams, & Finkelhor, 1993). One of the saddest
to the point of inflicting harm on others.
of these after-effects is that many of these victims
are much more likely to abuse their own children. Kaufman and Zigler (1987) reviewed the many studies in this area and concluded,
“approximately one-third of all individuals who were physically abused, sexually abused,
or extremely neglected will subject their offspring to one of these forms of maltreatment”
(p. 190). Conversely, most adults who abuse children were themselves abused as children.
In one typical study, Kasper and Alford (1988) studied 125 men who had sexually abused
children and found that approximately 85% were themselves abused. The experience of
abuse can profoundly influence a child’s present and future behavior.
Aggression
One of the consequences of childhood abuse is a 50% increase in the probability that boys
will behave violently when they become adults. But that statistic also indicates that not all
boys who are abused become violent. Why do some boys become violent but not others?
One possible answer is genetics. Animal research has shown that an enzyme called monamine oxidase A (MAOA) plays an important role in reducing aggression, and that a single gene regulates production of this enzyme. Perhaps the reason that some abused boys
are more likely to become violent is that they lack this inhibitory gene.
In one study, males who had been abused as children and lacked the MAOA gene were
found to be roughly six times more likely to be convicted of violent crimes than were males
without these predisposing factors. In other words, just two factors—a history of abuse
and the absence of a single gene—were enough to almost completely determine how these
boys would behave when they became adults (see also Miles & Carey, 1997).
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A second, perhaps surprising, determinant of aggression is nutrition. Several studies have
shown that poor nutrition is associated with a wide range of violent and criminal behaviors, and that improving nutrition can substantially reduce this behavior.
The Feeling of Freedom
Findings such as these pose a puzzle: If our behavior is influenced so strongly by our
heredity and environment, how is it that in our everyday lives we do not experience any
sense of being controlled? When you decide what clothing to wear or what to eat for
lunch, you have no sense of compulsion that you must act in a certain way; quite the contrary, you freely decide. How can our behavior be determined if we constantly feel so free?
The answer proposed by determinists is that although we may feel free in such situations,
we are still controlled. We are just less aware of the forces influencing us.
Advertising
A classic example of how we can be influenced without realizing it is advertising. Most
of us believe that we are not influenced by advertisements—we insist that we base our
decisions solely on evidence. Some research, however, suggests that we are all more susceptible to advertising than we realize. In one study on this point, Smith and Engel (1968)
showed 120 men a picture of an automobile. For half the subjects, the photograph showed
only the car, whereas for the other subjects the car was shown with a sexy redheaded
woman standing in front of it. After examining the picture, participants were asked to
evaluate the car on several dimensions. Those who saw the car with the attractive female
rated the car as significantly more appealing and better designed. They also estimated it to
be more expensive (by an average of $340), faster, and less safe.
When the authors later asked a
subset of the participants if their
ratings had been influenced by
the presence of the model, 22 out
of 23 denied it. One respondent
claimed, “I don’t let anything
but the thing itself influence my
judgments. The other is just propaganda.” Another commented,
“I never let myself be blinded by
advertising; the car itself is what
counts.” Thus, although the
model’s presence clearly altered
the participants’ ratings of the One classic study on advertising found that products portrayed
car, virtually none believed that in images with attractive women were much more likely to
appeal to male consumers.
they had been affected.
Sexual Attraction
Another illustration of how the environment can influence us without our realizing it
comes from research on sexual attraction. Why is it that we are sexually attracted to
some individuals but not to others? Psychologists are still in the early stages of trying
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to understand attraction, but some interesting evidence has begun to emerge. One early
study, by Dutton and Aron (1974), was carried out in an unusual setting for a psychology
experiment—a deep river gorge in British Columbia. There were two ways of crossing the
river: a narrow, wobbly footbridge located some 230 feet above rapids, or a much more
substantial wooden bridge only 10 feet above a small rivulet. Men were approached as
they crossed either bridge by an attractive woman who asked if they would answer some
questions for a research project. When the interview was over, she gave the men her telephone number in case they later had any questions.
The real purpose of the study was to measure sexual attraction—would the men later
phone to ask for a date? Many did, but the study’s striking finding was that the proportion
asking for a date depended on where the interview took place: Half the men interviewed
after crossing the rickety bridge later phoned for a date, compared with only 12% of those
interviewed after crossing the solid bridge.
On the surface this result might seem bizarre—why should the location of the interview determine whether men think a woman is attractive? Dutton and Aron, however, had predicted
precisely this result on the basis of a theory of emotion previously proposed by Schachter
and Singer (1962). We will not review the theory in detail, but in essence it proposes that all
emotions are characterized by similar states of physiological arousal—increased heart rate,
rapid breathing, and so on. Schachter and Singer argued that we therefore need to rely on
environmental cues to help us identify what emotion we are experiencing. When the men
experienced strong arousal when crossing the high bridge and then encountered the attractive interviewer, they would have unconsciously thought, “Aha, it must be her beauty that
is making me feel so excited.” And believing that they were attracted to her, they were more
likely to ask her for a date. They would have felt that the decision to do so was entirely free,
but they were being influenced by factors of which they were unaware.
Political Attitudes
A third example comes from research on how people decide what political party to support. We normally assume that we make decisions as important as these by evaluating the
positions of the different parties, but as with the two previous examples, research suggests
that our choices can be powerfully influenced without our being aware of it happening.
One example comes from research by an Israeli psychologist, Ran Hassin, who asked
both Israelis and Americans questions about their political beliefs. The questions were
presented on a computer screen, with a picture of their national flag flashed on the screen
very briefly before each question appeared. Each presentation of the flag lasted less than
1/50th of a second and was followed by a jumbled set of lines called a pattern mask.
Previous research had shown that masking stimuli presented under these conditions
effectively erase preceding stimuli before subjects can become aware of them. The procedure is sometimes referred to as subliminal presentation—limen being the Latin word for
threshold, so “subliminal” indicating that the stimulus remains below the threshold of
consciousness. The experimenters interviewed participants afterward to determine if they
had been aware of the flags. None had. So, did the presence of the flag influence participants’ political views, even though they were not aware of it?
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Section 1.2 How Should We Discover Any Laws?
One study found that Israelis who viewed a subliminal image
of their flag exhibited increased prejudice toward Palestinians;
similar results were found in a study in which an American flag
was used to influence Americans’ preference for a presidential
candidate. Results such as these support the notion that
our political attitudes may be shaped by factors other than
conscious choice.
CHAPTER 1
It did. Hassin et al. (2009) found
that subliminal exposure to the
Israeli flag increased Israelis’
feelings of prejudice toward
Palestinians, and they found
comparable effects in a U.S.
study. This study, conducted
in 2008, asked citizens whether
they intended to vote for Barack
Obama or John McCain; subliminal exposure to an American
flag while answering increased
support for McCain and
decreased support for Obama.
(See also Ballew & Todorov,
2007; Rutchick, 2010.)
So, Is Behavior Lawful?
It seems clear that our heredity
and environment do influence
much of our behavior, ranging from whom we find attractive to what political parties we support. The fact that our
behavior is influenced, however, does not necessarily mean that it is entirely determined.
Even under the most intense environmental pressure, we possibly still retain some freedom to choose. Consider again the effects of sexual abuse on children. We have seen that
roughly one third of children who are abused go on to become abusers as adults. This also
means that two thirds of these children do not abuse as adults. Proponents of free will can
thus argue that even under the most terrible pressures, each of us retains some capacity to
choose our own path.
In the end, it is unlikely that the debate between free will and determinism will ever be
resolved conclusively. Not even the most optimistic determinist believes that we will ever
be able to predict every aspect of a person’s behavior—we would have to know every law
and record every moment of a person’s life to be able to calculate the cumulative impact
of all his or her experiences. Given that we can never fully predict behavior, it will always
be possible for believers in free will to argue that we have an essential inner freedom,
whereas determinists will claim that a belief in free will only reflects limitations in our
current state of knowledge.
It is doubtful we will ever know whether behavior is completely lawful. The evidence we
have reviewed, however, suggests that environment and heredity play a powerful role.
1.2 How Should We Discover Any Laws?
If behavior is lawful, at least to some degree, how can we determine the laws that dictate it?
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Introspection
If we want to understand why people behave as they do, one obvious approach is to ask
them; that is, to have them carefully observe their thoughts and feelings as they behave
and then report them, a technique called introspection. We are all introspective on occasion, and literature abounds with references to people “searching their souls” in an attempt
to understand themselves. The first systematic application of this concept, however, was
the work of a late nineteenth-century German psychologist, Wilhelm Wundt. The essence
of Wundt’s technique was simple: Subjects were exposed to a stimulus and then asked to
report the sensations aroused by it. Learning to report those sensations accurately required
long and arduous training. It was important, for example, that a subject report not only
what he or she saw (such as a chair), but the exact sensations the object elicited, the quality
and intensity of these sensations, how they changed over time, and so on.
This is surprisingly difficult. Suppose, for example, that you were shown a piece of black
coal next to a piece of white paper, and that the coal was illuminated by a bright light
while the paper was in shadow. If you were asked which was darker, you would almost
certainly say the coal, even if physically it was reflecting far more light. (If you looked at
the two samples through two holes in a screen, so that you didn’t know which was which,
the coal would appear far brighter to you.) The problem is that we often perceive what we
expect to see, rather than what is actually there.
Wundt’s subjects underwent extended training to overcome this and similar errors. Once
the observers were properly trained, Wundt hoped to use their reports to analyze the complex patterns of human thought into their constituent elements and then discover the laws
by which these elements are combined to produce the richness and variety of mental life.
Though the rigorous demands of Wundt’s technique seem daunting, the underlying logic
has great intuitive appeal. If we want to understand the processes of learning, what better way than by studying these processes within our own minds? Yet, despite its obvious
attractions, introspection gradually fell into progressively greater disrepute, until eventually it almost disappeared from psychology. One reason for this collapse was that even as
Wundt was painstakingly beginning to train his subjects, a Viennese physician named Sigmund Freud was developing his revolutionary theories—theories that would ultimately
destroy the rationale for introspection.
The Influence of Sigmund Freud
Freud exposed for the first time the world of the unconscious, its primitive swirl of emotions hidden behind powerful defensive barriers. This metaphor of subterranean forces
had devastating implications for introspection, because it attacked its foundational premise: a faith in the accessibility of all thought to conscious analysis. If consciousness was
only the visible tip of the mental iceberg, with vast areas of the mind concealed under
defensive barriers, then introspection could provide only an incomplete and fragmented
account of why we behave as we do.
Freud’s theories were the first to suggest that there might be limits to the power of conscious
analysis, but it seems likely that these limits would have become apparent eventually, with
or without Freud. Consider, for example, what happens when you try to prove a geometry
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theorem. You may struggle for minutes or even
hours, searching for a solution, when suddenly
the correct answer occurs to you. What happened
exactly? How did you suddenly go from being
confused to knowing the correct answer? Clearly,
some important mental processes intervened
between these two states, but, introspectively,
your mind is a blank slate from which the correct
solution spontaneously emerged. Our inability to
trace the processes involved in acts such as these
suggests limits to the usefulness of introspection
in analyzing complex thought and learning.
The existence of the unconscious means that
introspection can play only a limited role in helping us understand behavior. Still, you might think
that it could at least help us to understand conscious processes. Yet even here, serious doubts
soon arose over whether observers’ reports were
accurate. One example concerned a phenomenon
known as “imageless thought.”
Sigmund Freud was the first to propose
that much of human behavior was driven
by the subconscious mind.
Some psychologists believed that the meaning
of any word was simply the image that it produced—the meaning of the word “chair,” for example, would be the image that comes to
mind when you think about this word. This approach seems plausible when we consider
concrete nouns such as chair, but what of more abstract words such as “truth” or “meaning”? Do these words also produce images? One influential introspectionist, Oswald
Kulpe, reported that when he and his colleagues introspected, they could not detect any
trace of an image while thinking of such words. Another leading introspectionist, however, insisted that even the most abstract words produced images if you introspected carefully enough. In the case of meaning, for example, he reported seeing “the blue-gray tip
of a kind of scoop which has a bit of yellow about it (probably a part of the handle) and
which is digging into a dark mass of what appears to be plastic material” (Titchener, 1915,
p. 519). This image had its origins, he suggested, in injunctions from his youth to “dig out
the meaning” of Latin and Greek phrases. Each side insisted that the other was wrong,
and there was no way to resolve their disagreement.
The realization that much of the mind’s functioning is unconscious, coupled with the difficulty of reliably observing even those areas that ostensibly are conscious, eventually led
to the abandonment of introspection as a scientific technique.
The Experimental Method
As the limitations of introspection became clear, psychologists turned to experimentation to discover the causes of behavior. In outline, the experimental method is very simple: We deliberately change some aspect of the environment to see if it affects behavior.
Suppose, for example, that you are a clinical psychologist and want to find a treatment
for depression. The traditional approach is psychotherapy—talking to a client about his
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or her experiences to discover the emotional causes of behavior—but you believe that
depression is caused not by emotions but by chemical imbalances in the brain. The easiest
way to address this, you think, would be a regimen of vigorous daily exercise to increase
the flow of serotonin, a brain chemical that is known to enhance mood.
To see if this approach would be superior to psychotherapy, you could run an experiment,
offering one group of patients psychotherapy while training another to exercise daily.
If the exercise group improved more, this would support your view that exercise was a
more effective treatment.
The aspect of the environment that is altered (in this case, the therapy) is called the independent variable, and the behavior that is measured (in this case, depression) is called
the dependent variable. If there is a consistent relationship between them—for example,
environmental condition A is always followed by behavior B—this is called a law.
One Thing at a Time!
If experimentation were really so simple, discovering the laws of behavior would be
easy: All we would have to do is manipulate our independent variables, observe their
effects, and combine the resultant laws into a comprehensive account of behavior. The
problem is that we must manipulate only one independent variable at a time. If several independent variables changed simultaneously, it would be impossible to say which one
was responsible for the resulting behavior. The obvious solution, to ensure that only one
aspect of the environment changes during an experiment, turns out to be impossible in
many situations.
Consider again our depression example. On the surface, it seems a very simple experiment—the only difference between the groups was which treatment they received. In fact,
however, the groups could have differed in other ways. Suppose, for example, that the
experiment participants all viewed psychotherapy as a much more plausible treatment
than exercise; members of the psychotherapy group would then have a stronger belief
that they would improve through treatment, and this belief could have alleviated their
feelings of depression. In other words, the groups differed not only in which treatment
they received, but also in how hopeful they were that it would work, and the feeling of
hope might have produced the improvement.
Even if the subjects’ expectations of improvement were the same in the two groups, the
experimenters’ expectations could be different. Perhaps previous research had suggested
that psychotherapy was more likely to be effective, so that the experimenters expected
participants receiving this treatment to improve more. If so, the greater improvement in
this group might be due not to the treatment but to the fact that the experimenters expected
them to improve more.
Clever Hans
How could an experimenter’s expectations affect a subject’s evaluation of a picture? We
know very little about the underlying processes, but some evidence suggests that subtle
cues from the experimenter are involved.
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One of the classic examples of
such cues is the case of Clever
Hans. (See Pfungst, 1965.) Hans
was a horse that lived on a German farm at the turn of the century. Hans wasn’t an ordinary
horse: He was the only horse in
Germany that could add! When
asked the sum of two plus two,
for example, Hans would slowly
begin to tap the ground, one, two,
three, four . . . and then stop. Nor
was this simply a trick he had
memorized, because he could
add virtually any numbers, and
Clever Hans amazed the masses with his mathematical skill.
it didn’t matter who asked the
Ultimately, he was found to be less of a math genius and more
question. He was equally profiof a master of observation.
cient at subtraction and, incredibly, multiplication and division. An obvious explanation for his prowess was some sort
of signal from his master, but when a blue-ribbon panel of experts convened to investigate Hans’s extraordinary skill, they found that Hans performed equally well in his
master’s absence.
In a brilliant series of experiments, German psychologist Oskar Pfungst eventually discovered the explanation for Hans’s apparent genius. Pfungst found that Hans’s accuracy
was reduced if the person who asked the question didn’t know the correct answer. Furthermore, the farther away the questioner stood, the less accurate was Hans’s answer.
Finally, putting blinders around Hans’s eyes destroyed his performance. Clearly, Hans
could answer questions only if he could see someone who knew the correct answer. But
what visual cues could the questioner provide? The answer, Pfungst discovered, was
that questioners tilted their heads slightly forward as they finished their questions, and
this was Hans’s cue to begin tapping. As the tapping approached the correct answer, the
observers tended to straighten up in anticipation, and this slight tensing was Hans’s cue
to stop. Hans was extraordinarily sensitive to such cues, responding to the raising of eyebrows or even the dilation of nostrils, and Pfungst was eventually able to control Hans’s
tapping completely by producing these cues. Hans was an extraordinary horse, but his
genius lay in his powers of observation rather than any arithmetic ability.
Let us now return to our depression experiment. Suppose that we redesigned our experiment to ensure that the experimenter who ran the study expected both groups to improve
equally, and we again found substantially greater improvement in the exercise group.
Now, at long last, would we have proved that increasing exercise (and thus serotonin) is
an effective treatment for depression? Yet again, the answer is no. Why not? Because, even
if we can’t identify alternative explanations, that doesn’t prove there aren’t any. The blueribbon panel was unable to find any plausible explanation for Hans’s performance, but
that didn’t prove that he was a genuine math wizard.
An experiment, in other words, can never prove that a particular explanation is correct
because it is always possible that some alternative explanation will eventually be found.
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Experiments can support a particular explanation, and with sufficient evidence our confidence in that explanation can become very high—few now doubt the existence of gravity—but it is important to remain open to the possibility of other explanations.
The Nature of Scientific Progress
We started with a seemingly simple experiment, but the more we analyzed it, the more
complex it became. This is always the case. The goal of the experimental method is to
change only one independent variable at a time, but this ideal can rarely be fully realized.
We can control for the effects of particular factors, such as subject and experimenter expectations, but there are always changes that we cannot control—fluctuations in humidity,
the occurrence of sunspots, the death of an earthworm in China! This in turn has important implications for the nature of scientific progress.
Slow. . .
One such implication concerns the pace at which science sometimes progresses. A popular
image of science has the scientist in a white lab coat advancing through rigorous analyses.
In practice, scientific progress is often much more confused and halting. As we have seen,
it is impossible to control for all
possible variables; we can only
control for those variables that
seem important. Our notions of
what variables are important,
however, are often wrong.
For example, in 19th century
England, one of the most dangerous things a woman could
do was have a baby in a hospital. Many thousands of women
died every year after giving
birth. When Joseph Lister suggested that doctors could prevent these deaths if they washed Scientific progress can move at a slow pace and is more
their hands before delivering a confusing and halting than some people think.
baby, his proposal was greeted
with incredulity: How could having a doctor wash his hands with boiled-down animal
fat (soap) prevent a woman from dying? We now understand, thanks to the germ theory
of disease, that this action helps prevent infection. At the time the idea was first proposed,
however, it seemed preposterous. Similarly, in the case of Clever Hans, few would have
believed beforehand that a horse could be so sensitive to human body language.
There is thus a built-in catch-22 to scientific progress: To discover scientific laws, you must
control all important variables, but you can only identify the variables that are important
if you already know the laws! This problem is not insurmountable. We just have to plug
away, identifying important variables as best we can in experiments that may initially lack
important controls. This bootstrapping process means that progress will initially be slow
and frustrating as we struggle to identify the important variables.
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Section 1.2 How Should We Discover Any Laws?
Artificial
A second implication of our analysis concerns the inherent artificiality of experiments.
To isolate the effects of one variable, you need to hold others constant, but the more you
control the environment, the less like real life it becomes. The underlying strategy is summarized in Figure 1.1: You start with a complex environment and, by analysis, try to break
it into simpler environments so you can study the effects of constituent elements (A, B, C,
and so on) one at a time. Then, once you have determined the effects of each variable on
its own, you use the method of synthesis to recombine them, studying what happens when
two or more variables act together (AB, ABC, and so on). The scientific method thus proceeds by first analyzing complex environments into simpler ones, then gradually returning to the more complex environment that was the original focus of interest.
Figure 1.1: Breaking down a complex environment
complex
environment
A
B
complex
environment
C
synthesis
analysis
A
A
B
B
C
C
B
A
B
A
B
C
A
C
A
C
simple
environment
B
C
In trying to understand a complex environment, experimenters begin by examining the effect of each
variable individually (analysis); it is then possible to study how they act in combination (synthesis).
The analysis step requires highly simplified (and thus artificial) situations, so that only one variable is
allowed to change at a time; in the synthesis stages the goal is to move back toward more complex (and
thus realistic) environments.
In psychology, most research is still analytical, with the result that it is very easy to feel
depressed by its artificiality. After all, what does the behavior of a student in an artificial
laboratory setting have to do with real life? The answer lies in the assumptions we have
been tracing in this chapter. If behavior is lawful, and if the best way to discover those
laws is through well-controlled experiments, then eventually the principles discovered in
these artificial settings will help us understand behavior in the more complex conditions
of the real world.
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Section 1.3 Behavioral and Cognitive Approaches
CHAPTER 1
1.3 Behavioral and Cognitive Approaches
One reaction to the discovery that introspection is severely limited as a tool for studying
the mind was the emergence of a new approach within psychology called behaviorism.
Behaviorists such as John B. Watson argued that because it is not possible to study the
mind accurately, psychologists should instead focus on visible or overt behavior. Rather
than studying subjective feelings such as hunger, we should study visible behavior such
as eating. By focusing on behavior that could be observed, behaviorists hoped that psychologists would at least be able to agree on their data, thereby allowing theories to be
evaluated by solid evidence rather than by the eloquence or prestige of opposing theorists. If you want to understand the effects of rewards on children, for example, behaviorists argued that you should present rewards and observe their effects, not speculate about
what the children might be thinking.
Skinner’s Radical Behaviorism
Although all behaviorists agree on the importance of objective observations of behavior,
they disagree concerning what attention, if any, should be paid to mental states. B.F. Skinner developed one influential approach (for example, Skinner, 1953). Like Watson before
him, Skinner believed that the goal of psychology should be practical, helping with problems such as the best ways of rearing children, coping with phobias, and making education
more enjoyable as well as more effective. All these problems involve changing behavior,
and the only way to change anyone’s behavior is
to change his or her environment. If you want to
convince someone to vote for a particular political party, for example, you could try to do so by
talking to him about the party’s merits, but your
words would then represent a change in the person’s environment, and you would be hoping
that this would lead to a consequent change in
his voting behavior. If you want to change people’s behavior, therefore, you must understand
the environmental conditions that determine this
behavior.
B.F. Skinner was particularly influential
because of his advocacy of behaviorism,
with its practical focus on discovering the
environmental causes of behavior, rather
than speculating about the mind.
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To pursue this point, suppose that a friend tells
you that she has decided to vote for candidate X
for president. Why did she reach this decision?
The most obvious explanation is that she likes the
candidate. Skinner did not doubt the existence of
feelings such as liking, but he argued that it is a
mistake to explain behavior in terms of such feelings; we must go on to ask why people have these
feelings. In this case, perhaps your friend heard a
speech the candidate made and was impressed by
it. If so, Skinner believed that we should view this
speech as the cause of her voting behavior, rather
than the feelings that followed.
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Figure 1.2: A summary of Skinner’s views
Skinner
environmental
conditions
mental states
behavior
cognitive
psychology
B.F. Skinner recommended ignoring the mind and focusing on the direct relationship between
environmental conditions and behavior.
Figure 1.2 summarizes Skinner’s views. It outlines a sequence in which an environmental
condition gives rise to a mental state, which in turn produces behavior. To change this
behavior, we must understand the environmental conditions that produce it, and Skinner argued that we should study the relationship between environmental conditions and
behavior directly. It is not easy to ignore the mind—our private worlds consist of our own
thoughts and feelings, so we are inevitably fascinated by the possible thoughts and feelings of others—but Skinner argued that psychologists must focus on the environmental
determinants of behavior if they want to be able to help people.
Cognitive Approaches
A rather different approach to the role of the mind in psychology emerged from cognitive
psychology. (Cognition refers to the processes involved in thinking; cognitive psychologists try to understand these processes.) Cognitive psychologists are also behaviorists, in
that they believe that most operations of the brain are unconscious. If you ask people their
telephone number, for example, they will probably all respond immediately, but if you
then ask them how they managed to retrieve this information, they will probably just stare
at you. Most of the brain’s activity occurs at an unconscious level, so introspection is very
limited in what it can tell us.
Cognitive psychologists thus agree with other behaviorists that introspection is of limited
value, but they argue that this need not prevent us from studying cognitive processes.
Consider that physicists, for example, cannot directly observe the existence of atoms, but
this has not stopped them from developing theories about the properties of atoms and
other invisible particles, and these theories have led to discoveries that have transformed
our world. Similarly cognitive psychologists believe that an understanding of how the
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Section 1.4 The Use of Animals
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mind works would inevitably lead to better methods of education, more effective treatments for people with problems, and so on.
In essence, the disagreement between Skinner’s approach and that of cognitive psychologists concerns the desirability of theories about the mind. Both sides agree that the primary data of psychology must be objective observations of behavior. They disagree, however, about whether there is a useful role for theories about the mind. Skinnerians argue
that because behavior is ultimately determined by environmental conditions, our effort
should go into studying the effect of these conditions on behavior. Cognitive psychologists argue that because cognitive processes form a critical part of the causal chain that
controls behavior, a deeper understanding of these processes will inevitably lead to practical applications.
The Current Approach
The approach taken in this text can be seen as a blend of the Skinnerian and cognitive
approaches. We think Skinner was right to emphasize the importance of environmental
conditions in determining behavior. His emphasis on the practical application of learning
principles played a crucial role in encouraging applied research, and we will devote considerable attention to the applications that resulted.
We think that Skinner was also right to recognize the potential hazards in speculating
about the mind—it is all too easy to attribute behavior to invisible mental states, without
any evidence that these states really exist. However, we also agree with cognitive psychologists that these dangers can be avoided if theories are stated clearly enough that they
lead to testable predictions, and that under these circumstances they can substantially
enrich our understanding of behavior. Suppose, for example, that a theorist proposed that
reading involves three cognitive processes. If there were no way to test the truth of this
claim, the theory would be useless. On the other hand, if the theory led to testable predictions, and these were confirmed, then our understanding of these processes might allow
us to identify which process is impaired in different individuals, and thereby help us to
develop treatments tailored to their individual problems.
1.4 The Use of Animals
Having decided to study the laws of behavior, and to do so through careful experimentation, we now come to the question of what species to study. If our goal is to understand
human behavior, the answer might seem obvious: We should study humans. Given the
clarity of this logic, why have psychologists sometimes studied animals instead?
The Advantages of Using Animals
The reasons that psychologists study animals are complex, but all are rooted in the problems of experimental control discussed earlier. We said then that one crucial problem
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Section 1.4 The Use of Animals
in psychological research is to
manipulate only one independent variable at a time while
holding all others constant. One
way to do this is to exert stringent control over the environment, so as to minimize how
many variables change during
an experiment. Another, less
obvious, is to study an organism
with a simpler nervous system,
so that fewer variables are likely
to affect it and it is thus easier
to manipulate just one. Each
of these strategies is easier to
implement in research involving animals, and we will consider each in turn.
CHAPTER 1
There are several advantages to using animals in psychological
experiments. The use of animals limits the number of variables
and allows psychologists to study an organism with a simpler
nervous system.
Control of the Environment
For both moral and practical reasons, it is much easier to control an animal’s environment
than it is to control a human’s. For example, one problem of considerable importance in
human behavior concerns the effects of a child’s early environment on her or his development. Freudians have long argued that the first years of life are crucial in determining personality. More recently, educators have suggested that early sensory and social deprivation is an important factor in the poor school performance of some children (particularly
from underprivileged homes) and have urged governments to invest in compensatory
child-care programs for young children. How are we to determine whether the role of
early experience is really so crucial and, if so, which aspects are most important?
To determine the importance of early sensory experience, should we run controlled experiments in which half the children are reared normally while the other half are permanently confined to a barren environment, devoid of all stimuli? Similarly, to determine
the importance of a mother’s role in a child’s normal development, should we compare
children reared with their mothers and children reared in isolation? Such experiments
would hardly be humane or practical. The questions involved are significant, with serious
implications for the future structure of our schools and even our families, but the experiments necessary to answer such questions are clearly unacceptable.
Using animals as subjects, however, psychologists have conducted experiments to answer
these questions, with often fascinating results. Harry Harlow, for example, reported a series
of experiments with infant rhesus monkeys. When taken away from their mothers immediately after birth and reared in isolation, these infants became highly neurotic: They spent
much of their time huddled in corners, rocking back and forth and sucking their thumbs.
Furthermore, this pattern of disturbed behavior persisted into adulthood, and most of the
isolated monkeys were unable to function normally in a group, or even to mate.
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These studies supported the critical role of early
experience in social development, and in later
experiments Harlow and others isolated some
important variables. The presence of the mother,
for example, is not necessarily critical; infants
taken away from their mothers but reared with
other infants showed significantly less disturbance (Harlow & Harlow, 1965). Another finding, with poignant social implications for men, is
that male rhesus monkeys, which normally play
an insignificant role in child rearing, can, if necessary, replace the mother with no apparent ill
effects to either child or father (Mitchell & Brandt,
1972).
A similar line of experiments has examined the
role of early sensory experience in the development of rats. Some rats were reared in “enriched”
environments that included other rats and a variety of toys, platforms, colors, and sounds; other
rats were reared in “deprived” environments
The use of rhesus monkeys allowed Harry
that lacked these stimuli. Animals reared in the
Harlow to demonstrate the importance
enriched environments developed larger brains
of parental attachment to an organism’s
(Rosenzweig, 1984), with considerably more
mental and physical well-being.
complex interconnections among their neurons
(Turner & Greenough, 1985). These results suggest that early stimulation plays a critical
role in the brain’s development and thus in our capacity for learning in later life.
Simpler Systems
One advantage of using animals as subjects, then, is that we can more easily control their
environments and thus determine which variables are important. A related advantage
is that it is easier to identify fundamental principles when we study simpler systems.
Suppose, for example, that you wanted to understand the principles of electronics. You
would find it easier to understand these principles if you first studied a transistor radio
rather than a mainframe computer: The simpler the system, the easier it is to understand
its operations. Thus, scientists were able to isolate the fundamental principles of genetics by first studying two less complex life-forms—the fruit fly and the pea—that possess
simpler systems. Both of these organisms rely on fewer genes for development and function, and thus scientists could isolate the effects of these genes more easily. If scientists
had first tried to understand the principles of genetics in a more complex system—the
inheritance of intelligence in humans, for example, is almost certainly influenced by
many thousands of genes—we would probably still have little or no understanding of
the principles of genetics.
The less complex the system, then, the easier it is to determine its fundamental principles.
Determining the principles of behavior in animals, however, can help us to understand
human behavior only if these principles are similar. Is this assumption justified? Are the
principles of animal and human learning sufficiently similar that understanding animals
can help us to better understand humans?
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Are Animal and Human Behavior Similar?
Since the 19th century, when Charles Darwin first explained the mechanism by which
human and animal species evolved from common ancestors and were shaped by the same
environmental forces, animals have been found to have important physiological similarities to humans. Indeed, despite the incredible diversity of animal species (there are now
thought to be more than three million species, ranging in size from virtually invisible
microorganisms to the mammoth blue whale), the underlying biological principles are
surprisingly similar. Our understanding of human neurophysiology, for example, is built
largely on the pioneering work of Hodgkin and Huxley on the giant squid. Similarly, our
understanding of human vision is based on Hartline and Ratliff’s investigations of the eye
of the horseshoe crab, a primitive species almost unchanged from primordial times.
When we begin to examine species more closely related to humans, the similarities become
even greater. The basic principles of digestion, vision, respiration, locomotion, and so forth
are, for all practical purposes, identical across the various mammalian species, and it is
because of this fundamental similarity that modern medicine has been able to advance so
quickly. The drugs and surgical techniques on which our lives now depend were generally pioneered not with people, but with mice, monkeys, and the famous guinea pig.
For post-Darwin scientists, animals and people were clearly similar, at least in physical
construction. Behaviorally, on the other hand, this similarity was less obvious. Even if
humans had once been apes, the argument went, they had long since begun a unique
evolutionary path that left them the only animal capable of thought and symbolic communication. In recent years, however, evidence has accumulated that human beings are
not unique even in these areas.
Washoe
The most striking evidence has come from research on language. Because chimpanzees
are our closest relatives, many psychologists believed that if any animal could master
the rudiments of language, it would be chimpanzees. Early attempts to teach chimpanzees to speak, however,
met with little success. Hayes
and Hayes (1951), for example,
reared a chimpanzee named
Vicki in their home, but after
four years of effort Vicki had
learned a grand total of only
four words: mama, papa, cup,
and up. Subsequent research
on the anatomy of the chimpanzee vocal tract revealed that
they are not physically capable
of producing the full range of
sounds required for speech.
Vicki’s failure could have been In 1951, Hayes and Hayes attempted to teach a chimpanzee to
because of this physical limita- speak, but the chimpanzee only learned a total of four words.
tion rather than any deficiency Further research concluded that a chimpanzee may learn a
in her intellectual capacity.
language that does not require speech: American Sign Language.
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To test this hypothesis, Allen and Beatrice Gardner set out to teach a chimpanzee to use a
language that did not require speech—American Sign Language for the deaf. The subject
for their study was a baby chimpanzee named Washoe, and the results were dramatic. By
the time she was five, Washoe had learned more than 130 signs and was able to use them
reliably in a variety of situations. The sign for dog, for example, was elicited by a wide
variety of dogs, both living and in pictures, and even by the barking of a dog that could
not be seen. Washoe also demonstrated some ability to combine signs; when she wanted
a refrigerator opened, for example, she signed “open food drink” (Gardner, Gardner, &
Van Cantfort, 1989).
When the Gardners’ research was published, it provoked intense controversy (see, for
example, Terrace, 1985; Pinker, 1994). To some degree, this was because of genuine problems in the methodologies used, but in some cases it probably also reflected disbelief
that any animal was capable of language, a skill that for so long had been assumed to
be uniquely human. At the heart of the controversy was whether the chimpanzees really
understood the signs that they were using. If Washoe was hungry and made the sign
for banana, did this mean that she understood what this sign meant, or was she simply
repeating a movement that had been rewarded with food in the past? A chimpanzee making a sign might be behaving no more intelligently than a rat pressing a bar—both might
simply be repeating behavior that had previously produced food.
The key issue was what linguists call semanticity, whether when a word is used it is evoking some sort of mental representation of the named object. In our banana example, when
Washoe saw this sign, did it evoke some representation of a banana in her brain? Because
we cannot observe animals’ mental states, there will probably always be some level of
doubt. Several studies published since the Gardners’ work, however, support the claim
that chimpanzees understand the signs that they use. We will look at two examples.
Our first, rather poignant example involves Washoe. After her period of active training
ended, she became a mother at the age of 15. Her baby was ill at birth, and Washoe had to
be anesthetized so that the infant could be removed for treatment. He recovered and was
returned to her, but several weeks later he again became ill, so that a pediatrician again
needed to anesthetize her. When she saw the needle, she began to scream and sign “My
baby, my baby.”
Sadly, the infant died. When Washoe saw her trainer the next day, her first sign was
“Baby?” The trainer replied by signing “Baby gone, baby finished.” Washoe’s response
was dramatic:
Washoe dropped her arms that had been cradled in the baby sign position
. . . broke eye contact and slowly moved away to a corner of the cage . . . She
continued for the next several days to isolate herself from any interactions
with the humans and her signing dropped off to almost nothing. Her eyes
appeared to be vacant or distant. (Fouts, Hirsch, & Fouts, 1982, p. 170)
This account is anecdotal and therefore must be treated with caution, but it is difficult to
read it without feeling that Washoe had some understanding of the meaning of the signs
that were used. (For a more formal test of understanding, see Savage-Rumbaugh, Rumbaugh, Smith, & Lawson, 1980.)
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Kanzi
An alternative strategy for bypassing the limitations of chimpanzee’s vocal cords was
developed by Duane Rumbaugh of Georgia State University, and later continued in collaboration with his wife, Sue Savage-Rumbaugh. They, too, believed that it was a mistake
to try to teach chimpanzees to speak, but instead of using sign language, they developed
a new language using geometrical shapes (lexigrams) as words. The lexigrams were displayed on a keyboard linked to a computer, and subjects could choose words by pressing
the appropriate symbol on the board.
The chimpanzees trained in this program soon showed performances very similar to those
of Washoe. One of the participants, a female named Lana, developed an intriguing ability to create novel word combinations. Some of the foods that she ate were not assigned
lexigrams by the experimenters, and Lana therefore invented her own names to request
them. When she wanted a cucumber, for example, she asked for “banana which-is green,”
and she requested an orange by using the lexigrams for “apple which-is orange (color)”
(Rumbaugh & Savage-Rumbaugh, 1994).
Another participant was a bonobo chimpanzee
named Kanzi. (Bonobos are one of two chimpanzee species.) Kanzi’s mother was one of the early
participants in the program, but she proved to
be a very slow learner and made little progress.
Though Kanzi was present during his mother’s
training sessions, the experimenters made no
effort to train him. Nevertheless, when Kanzi was
2 years old, the experimenters discovered that
he understood the meaning of the lexigrams that
the experimenters had tried and failed to teach
his mother. Simply by watching this training, he
seemed to have worked out for himself what the
symbols meant. The experimenters then initiated
an active training program for Kanzi, and by the
time he was 5½, his lexigram vocabulary had
increased to 149 words.
At this point, Kanzi astonished the experimenters
for a second time when they realized that he had
also learned to understand human speech. Again,
simply by listening to the conversations of his
Kanzi was an example of a chimpanzee
trainers as they taught him to use the lexigrams,
who astonished human researchers with
Kanzi had learned the meaning of a number of
his ability to understand human speech.
English words and phrases. In one test of his abilities, he was placed in a room containing 12 objects and given verbal instructions about
what to do with these objects. (The experimenter was located in an adjacent room behind
a one-way mirror, to avoid inadvertently providing Kanzi with cues through gestures.)
One of the instructions, for example, concerned a sponge ball that had eyes, a nose, and a
mouth; Kanzi was told “Feed your ball some tomato.” Even though Kanzi had never been
asked to do anything remotely like this, he immediately picked up the ball and tried to
place a tomato in its mouth. To provide a baseline for comparison, Alia, the 2½-year-old
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Section 1.4 The Use of Animals
CHAPTER 1
daughter of one of Kanzi’s caretakers, was also tested with the same set of instructions;
Kanzi responded correctly to 74%, Alia to 66% (Savage-Rumbaugh, et al., 1993; SavageRumbaugh, Rumbaugh, & Fields, 2009).
More than 100 years ago, Charles Darwin wrote that “The difference in mind between
man and the higher animals, great as it is, certainly is one of degree and not of kind” (Darwin, 1871/1920, p. 128). The evidence on this point is not yet conclusive, but it is already
clear that animals are far more intelligent than once believed. This does not mean that animals and humans are identical. Every species is unique, and it would be foolish to expect
to gain a complete understanding of people from the study of pigeons or white rats. On
the other hand, given that animals and humans have shared millions of years of evolution, it would be surprising if there were not also similarities. Just as research with fruit
flies and the pea made possible the extraordinary advances in genetics in the last century,
so research on animals might help us in understanding our own behavior.
Ethical Issues
Because it is possible to exert much greater control of the environment in experiments
on animals, such research has the potential to significantly enhance our understanding
of basic processes. On the other hand, the very similarity of animal and human behavior
that makes research on animals attractive also raises serious ethical issues. If animals
are similar to us in intelligence, and presumably also in feelings, how can we justify
confining them in cages and, in some cases, subjecting them to painful stimuli such as
electric shocks?
One view is that such research cannot be justified, because animals are living creatures
that have just as much right to life and freedom as humans. This position is attractive in
its strong value for all life, but few people hold it in its pure form. Suppose, for example,
that you had a child who contracted rabies, and that the only way to save the child’s life
required killing a mouse. Would you do it? Very few people faced with this dilemma
would not choose to save the child, implicitly valuing a child’s life more than that of a
mouse.
Rightly or wrongly, then, most people do value human welfare more than that of animals,
but this does not imply that animal life is worthless. Thus, the problem remains of deciding whether the benefits of particular experiments with animals outweigh the cost to the
animals. To assess this, we need some method of quantifying both the benefits and the
costs; in practice, though, this is difficult if not impossible. Suppose, for example, that we
wanted to assess the cost to the subjects of an experiment on the effects of punishment.
How could we decide how much pain a rat would experience if it were given an electric
shock? What if we substituted a fish or a cockroach as the experimental subject? Do they
also feel pain? If so, is it more or less than that experienced by the rat?
If it is difficult to find an objective way to assess the costs of animal research, it can be
equally difficult to assess its benefits. In our hypothetical rabies example, we assumed
that killing the mouse would save the life of the child, but the benefits of experiments
are rarely this predictable. Experiments that seem minor when they are performed can
eventually have momentous theoretical and practical benefits. In a study by Comroe and
Dripps (1977), for example, physicians were asked to rate the ten most important advances
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CHAPTER 1
Section 1.5 Learning: An Overview
in cardiovascular and pulmonary medicine and surgery. A total of 663 studies were found
to have been crucial in leading to these breakthroughs; 42% of them involved experiments
that, at the time they were reported, seemed unrelated to the later clinical application.
When doing basic research, it is difficult to predict what benefits might eventually be
derived from enhanced understanding of a fundamental mechanism.
In deciding whether a planned experiment is justifiable, then, it is difficult to assess either
the costs to the animals used or the long-term benefits to humans. There are no simple
guidelines; all we can say here is that an assessment of the benefits depends heavily on
the validity of the assumptions discussed in this chapter. If behavior is lawful, if experimental research is the best way to discover these laws, and if animal and human behavior
is similar in important respects, then research on animals might play an important role in
increasing our understanding of human behavior.
1.5 Learning: An Overview
Summarizing our discussion until this point, we have suggested that psychological
research is based on several assumptions: that behavior is lawful, that the best way to
discover these laws is through controlled experiments, and that research on animals
can sometimes help us understand human behavior. Before proceeding to examine the
research that has resulted from these assumptions, though, we need to address one final
question—namely, what this book is about. Of course, you already know that it is about
learning, but in this section we will examine more closely what we mean by this term.
Learning
Learning is a vast topic. It affects almost everything we do, from making friends to riding
a bicycle to learning organic chemistry. As a result, it is impossible to cover every aspect
of learning in a single course, and it has become customary to study different aspects in
different courses: Courses on developmental psychology deal with one aspect, courses on
educational psychology with another, courses on cognition a third, and so on.
Within this division, courses on learning generally concentrate on a particular form of
learning called associative learning. To explain what associative learning is, we will begin
by examining what we mean by the broader term learning.
Some stimuli always elicit the same reaction. If you accidentally touch a hot pan, for
example, it will make you pull your hand back every time; if a sudden gust of wind hits
you in the eye, it will make you blink every time. In cases like this, in which a stimulus
always elicits the same response, we call the stimulus-response relationship a reflex.
We can represent the way a reflex works in the following way, where S = stimulus, and
R = reflex:
Reflex: S
R
Our definition of a reflex requires that the stimulus always elicit the same response, but
under some conditions the strength of a reflexive response can change with experience.
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Section 1.5 Learning: An Overview
Suppose, for example, that you were quietly studying in your room one day when you
suddenly heard a deafening noise—a particularly loud burglar alarm in the building next
door to you had just gone off. This sharp noise would almost certainly make you jump, a
reaction that is known as the startle reflex. The first time it happened, your reaction would
be very intense, but if it happened again five minutes later, you would probably react less
strongly; a third repetition would produce even less of a reaction, and so on. This decrease
in the strength of a reflex when the stimulus is repeated a number of times is called habituation; it is a common characteristic of reflexes, especially when the stimulus is repeated
within a relatively short period of time.
One experiment illustrating habituation was reported by Davis (1974). He placed rats in
a cage that was mounted on springs, so that if they made a sudden movement he could
measure the magnitude of this movement by measuring the movement of the floor. He
then presented a loud tone to the rats a number of times. As shown in Figure 1.3, he found
that the tone initially produced a strong startle response, but that the magnitude of this
response decreased over successive presentations.
Figure 1.3: Magnitude of the startle response
Mean Startle Amplitude
40
30
20
10
0
0
2
4
6
8
10
Blocks of 10 Tones
As evidenced by Davis in 1974, the startle response diminishes with repeated presentations of a tone.
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CHAPTER 1
Section 1.5 Learning: An Overview
Why did the rats’ reactions to the tone habituate when it was presented repeatedly? One
possibility is sensory fatigue—frequent presentations of the tone could have impaired the
capacity of the sensory system to react. A closely related possibility is motor fatigue—as
the rats responded to the tone on successive trials, they could have become progressively
more tired and thus physically less able to respond. Although sensory and motor fatigue
undoubtedly can occur, habituation is rarely caused by such fatigue. If, at the conclusion
of his experiment, Davis had presented a test trial in which he had increased the intensity
of the tone, he would almost certainly have observed an increase in the vigor of the startle
response back to its original level. If so, the rats’ sensory and motor systems would clearly
have been capable of producing a response, and the weakened responding on earlier trials
could not have been caused by fatigue.
Defining Learning
Habituation, then, is not caused by fatigue in either the senses or the muscles; by elimination, it seems to involve some sort of change in the nervous system that links them.
Specifically, habituation seems to involve learning that a potentially dangerous stimulus
is not, in fact, dangerous, and thus can be safely ignored.
Changes in behavior of this kind illustrate what we mean by learning. It is difficult to
define learning precisely, but one simple definition would be a change in behavior due to
experience. As sometimes happens with simple definitions, however, this one quickly presents a challenge.
One problem, as we have already seen, is that there are some changes caused by experience that are really not what we mean by learning. If your behavior changed because you
had not eaten for several hours, for example, that would hardly be an example of learning.
Intuitively, what we mean by learning is experiences that result in the storage of information in our brains, information that alters our capacity to respond in the future. If you were
taught to ride a bicycle, this would be an example of learning whether or not you later
chose to use this skill.
To capture the meaning of learning more precisely, we will redefine the term as a change
in our capacity for behavior, as a result of particular kinds of experience. This definition is
regrettably more cumbersome, but it comes closer to what we really mean when we talk
about learning.
Associative Learning
In the case of habituation, learning occurs as a result of the presentation of a single stimulus (however, see Whitlow & Wagner, 1984). A more elaborate form of learning occurs
when two events occur together and we learn about the relationship between them. If
we use the symbol E1 to represent one event and E2 to represent the second event, then
in associative learning we learn about the association or relationship between the two
events:
E1
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E2
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Section 1.5 Learning: An Overview
CHAPTER 1
The two events could potentially be anything: a drop in air pressure warning of a storm
to come; a television theme tune announcing the start of a TV show; a tone of voice signaling annoyance. Learning psychologists, however, have been particularly interested in
instances of associative learning where the second event is biologically important—food,
say, or bodily injury—and survival might depend on being able to predict this event.
Suppose that a lion always visits a watering hole at 4:00 in the afternoon; if antelopes that
lion), this
also use this water could learn this stimulus-stimulus relationship (4:00 P.M.
would allow them to avoid the area at this time and thereby prolong their lives. Or consider a related situation from the lion’s point of view: Suppose that whenever it stalks an
antelope while remaining downwind of it, it is more likely to succeed. If it could learn this
succulent antelope), then it too
response-stimulus relationship (downwind stalking
would enjoy a longer, more satisfying life.
Classical Conditioning
In those cases in which an important event is reliably preceded by a stimulus, the stimulus often comes to elicit the same behavior as the event it predicts. If the presentation of
a light is repeatedly followed by a puff of air to the eye, for example, then the light on its
own would eventually begin to elicit a blink. This is an example of classical or Pavlovian
conditioning. Classical conditioning allows us to prepare for forthcoming events; in our
eyeblink example, if we blink before the puff arrives, the lid closure can prevent particles
from being blown into our eyes.
Operant Conditioning
When an important event follows a response rather than a stimulus, the result is often a
change in the response’s probability, and this is called instrumental or operant conditioning. If your parents gave you a sports car every time you received an A for a course, you
would probably increase the amount of time you spent studying. This example illustrates
one of the two subtypes of operant conditioning—reinforcement and punishment, that
differ in whether the change in response is an increase or a decrease. In reinforcement,
the consequence that follows a response is desirable and the effect is to strengthen it—the
use of a reward to increase studying, for example. In punishment, on the other hand, the
consequence is undesirable and the effect is to weaken the response. Children who burn
their hands when touching a hot pan quickly learn not to repeat this behavior.
As summarized in Figure 1.4, the essential distinction between classical and operant conair
ditioning lies in whether an important event follows a stimulus (for example, light
burn). As we shall see, both forms of
puff) or a response (for example, touching pan
conditioning play a major role in shaping our lives. This might not be obvious for classical conditioning because classical conditioning often occurs without our awareness (see
Chapter 4). Also, the best-known conditioned responses are salivation and blinking, neither of which would probably make a “top 10” list of critical skills. However, classical conditioning also affects far more important aspects of our behavior, including emotions such
as fear and sexual arousal, what foods we like, and the effects of drugs such as heroin and
alcohol. Learning psychologists have been able to use an understanding of the processes
involved to develop therapies for problems such as phobias, alcoholism, and bed-wetting.
We will look at the principles of conditioning, and how they can be practically applied, in
Chapters 2 and 3. We will also examine theories of conditioning in Chapter 5.
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Section 1.5 Learning: An Overview
CHAPTER 1
Figure 1.4: Varieties of associative learning
Associative learning involves the detection of relationships between events (E), where the events
concerned can be responses (R) or stimuli (S), and the stimuli can be positive (SPOS) or negative (SNEG).
The importance of reinforcement and punishment is probably more obvious, but even
here we tend to underestimate significance. As in the case of classical conditioning, this
is partly because we are not always aware of effects. Attention from others, for example,
can be very reinforcing, and when parents and teachers pay attention to a child who is
misbehaving they sometimes inadvertently reinforce the behavior they are trying to eliminate. Also, reinforcement and punishment sometimes appear ineffective because they
are not used optimally. Improved understanding of the principles involved has allowed
psychologists to develop techniques to reduce children’s misbehavior, to teach convicts
to master a year’s worth of school in only a month, and to help autistic children to lead
normal lives. We will look at the principles of reinforcement in Chapter 5 and their application in Chapter 6.
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Review Questions
CHAPTER 1
Summary and Review
In this chapter we reviewed some of the assumptions that underlie the research that we
will discuss in later chapters.
•
•
•
Human behavior is lawful, as our environment and heredity jointly determine
how we behave. The position that we have labeled neural determinism argues
that behavior must be lawful. We also looked at examples in which environment
and heredity strongly influence us, and evidence that such influence can occur
without our awareness.
Introspection is of limited value in helping us to understand people’s behavior.
Experiments allow us to identify which aspects of our environment affect our
behavior, but progress is often constrained by the need to manipulate only one
aspect of the environment at a time.
Researchers can more easily control the environment when designing and conducting experiments on animals, which makes it easier to identify the processes
involved. An understanding of how animals learn has the potential to help us
understand learning in humans. However, this similarity also raises ethical issues
about the use of animals in experiments.
Remember that these are all assumptions—it is important to understand the reasoning
behind them, but you don’t have to accept them.
•
•
We also introduced the term learning, which we defined as a change in our
capacity for behavior as a result of particular kinds of experience.
Our discussion of learning will focus on associative learning, which involves
learning about the relationship between two events. In classical conditioning, we
learn about the relationship between two stimuli; in operant conditioning (reinforcement and punishment), we learn about the relationship between a response
and its consequence.
Review Questions
Research on memory has shown that one of the most effective techniques for remembering material you are studying is to review after reading it, both immediately and then
again after a delay (e.g., Karpicke & Roediger, 2010). Reviews of this kind can be hard
work, and the effort involved often seems unnecessary because immediately after reading
a chapter it is still fresh in our memory, giving us the impression that we really know it
well. Unfortunately, this impression can be seriously misleading—while the material may
still be present in our temporary or short-term memory store, it may not yet have been
transferred to our more permanent, long-term store. One of the best ways to ensure that
you really will remember is to pause after each section that you read and try to recall it
without looking back at the text, and then to review it again when you finish the chapter. Such reviews can help you to identify material which you didn’t understand as well
as you thought, and also, make it much, much easier to retrieve the material later—for
instance, to use a wildly hypothetical example, in an exam.
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Concept Check
CHAPTER 1
You can use the review questions provided at the end of each chapter to help you in this.
Try to answer the questions without looking back at the text, and then reread any material you had difficulty remembering. The more often you practice retrieving material from
memory—for example, quizzing yourself the next day while eating lunch or having a
snack—the more likely you are to remember that material in the long-term.
Here are some review questions for this first chapter:
1. Is human behavior lawful? What are the arguments for and against this view?
2. In what ways do the views of Skinner and of cognitive psychologists differ? In
what respects are they the same?
3. How do experiments control for unwanted variables?
4. What are the strengths and weaknesses of the experimental method?
5. Why do psychologists believe that the results of experiments carried out in highly
artificial laboratory settings can tell us something about behavior in the real world?
6. What are the arguments for and against the use of animals in psychological
research?
7. How does the text define learning? What are the main types of learning discussed
and how is each defined?
Concept Check
1. In experimental research, animals are frequently used as subjects because
a.
b.
c.
d.
animals have a higher tolerance for pain in a controlled environment.
animal behaviors are easier to manipulate in an open environment.
animal behaviors are easier to manipulate in a controlled environment.
animals have a lower tolerance for pain in an open environment.
2. Milgram’s research on obedience yielded unexpected results. He found
a. 65% of the subjects continued to administer shocks regardless of the recipients’ level of pain.
b. 65% of the subjects ceased to administer shocks due to the recipients’ level
of pain.
c. 35% of the subjects ceased to administer shocks due to the recipients’ level
of pain.
d. 35% of the subjects continued to administer shocks regardless of the recipients’ level of pain.
3. Kasper and Alford (1988) studied 125 men who had sexually abused children.
Of these men, 85% were abused as children. Data from this study indicates that
a. 85% of child sexual abusers are men.
b. children who are sexually abused will likely abuse children when they are
adults.
c. 15% of the men did not sexually abuse children.
d. 85% of men who sexually abuse children will not abuse their own children.
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CHAPTER 1
Key Terms
4. Harlow’s research with monkeys supported the notion that the environment
plays a critical role in cognitive development. Newborn monkeys removed from
their mothers and placed in a sterile environment exhibited
a.
b.
c.
d.
normal social behavior and cognitive development.
abnormal social behavior and normal cognitive development.
abnormal social and cognitive development.
normal social development and abnormal cognitive development.
5. Research using animals has ethical implications, such as weighing the benefits
of the findings to the cost to the animal. The primary reason animals are used in
research is
a.
b.
c.
d.
animals are like humans.
animals feel less pain.
animals adapt easily to diverse environments.
animal’s environment can be controlled.
Answers: 1) c, 2) a, 3) b, 4) c, 5) d
Key Terms
associative learning A more elaborate
form of learning that occurs when two
events occur together and we learn about
the relationship between them.
behaviorism The view that psychology
should focus on visible behavior rather
than mental states.
classical (Pavlovian) conditioning An
increase in responding to a stimulus
because of pairings of that stimulus with
an important event such as food.
cognitive psychology A branch of psychology that tries to understand the processes
involved in thinking. Because so many of
the processes occur at an unconscious level,
cognitive psychologists use experiments to
infer the nature of these processes, rather
than trying to observe them directly.
dependent variable The observable
behavior that is measured during an
experiment, to see if it is affected by the
manipulation of the independent variable.
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determinism The view that all behavior is
caused by either environmental or genetic
factors.
experimentation A method for uncovering the causes of behavior by changing one
aspect of the environment (the independent variable) and observing its effect on
some other aspect of behavior (the dependent variable).
free will The belief that people have the
power to determine their own actions,
regardless of any external pressures.
habituation The decrease in the strength
of a reflex when a stimulus is repeated a
number of times.
independent variable The aspect of the
environment that an experimenter changes
during an experiment.
introspection A person’s examination of
his or her own thoughts or feelings.
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Key Terms
CHAPTER 1
law In science, a consistent relationship
between independent and dependent variables such that the occurrence of some set
of conditions A always leads to outcome B.
operant (instrumental) conditioning
A change in the probability of a behavior
due to its having been followed by an
important event.
learning A change in the capacity for
behavior due to particular kinds of
experience.
punishment A form of operant conditioning in which the likelihood of a behavior
is reduced because it produces an aversive
consequence.
neural determinism The argument that
the brain controls behavior, and that the
physical and chemical processes involved
in the transmission of neural signals are
lawful; hence behavior must also be lawful.
neurons Cells whose function is to transmit electrical signals.
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reinforcement A form of operant
conditioning in which a behavior is
strengthened because it produces a positive consequence.
reflex A stimulus-response relationship in
which a stimulus reliably elicits the same
response innately, without prior experience.
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2
Foundations of Classical Conditioning
Learning Objectives
After reading this chapter, you should be able to do the following:
• Understand the fundamental contribution made by the Associationist tradition to a theory of
human behavior based on associations.
• Identify and describe the main principles of association: frequency, intensity, and contiguity.
• Describe Ivan Pavlov’s research with salivary conditioning in dogs...
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