Chapter 9: Learning Theory



In Freudian theory, normal and abnormal human behavior result from conscious and unconscious mental forces (see Chapter 8). In the behaviorist view, behavior results from adaptive and maladaptive learning. For example, the psychoanalyst believes that a 35-year-old woman’s unexplained, disabling fear (phobia) of animals is caused by a repressed frightening experience. The behaviorist claims that the woman simply made an exaggerated or erroneous association in childhood between animals and pain and now experiences mental pain and fear in the presence of animals.

The idea that behavior is acquired by learning is more optimistic than the Freudian view. Because behavior that has been learned can be “unlearned,” it is more easily modified and improved than behavior that results from unconscious and hence obscure mental forces.

Mechanisms of learning include simple forms, such as habituation and sensitization, and more complex types, including classical conditioning, operant conditioning, and modeling. These mechanisms form the basis of treatment techniques (see Chapter 11) aimed at increasing the frequency of desired behavior and decreasing the frequency of unwanted behavior.

Habituation and Sensitization

Habituation and sensitization are the simplest forms of learning. In habituation, repeated stimulation results in a decreased response; in sensitization, repeated stimulation results in an increased response. Eric Kandel received the Nobel Prize in 2000 for research that showed that habituation and sensitization can be demonstrated even in a relatively uncomplicated organism, the marine snail Aplysia. A touch to the snail’s siphon caused a withdrawal response; with repeated touching, the withdrawal response decreased. If the snail’s siphon was initially stimulated with a strong electric shock, only very slight stimulation was subsequently needed to elicit a withdrawal response. A clinical parallel of this experiment can be seen in young children who receive weekly allergy injections. Almost all children cry at the first injection, but with repeated injections, crying decreases in some children. Other children, particularly those whose first injection was very uncomfortable, show more fearfulness and crying with each ensuing injection.

Classical Conditioning

In classical or respondent conditioning, a natural, reflexive, or unconditioned response (a behavior) is elicited by a learned or conditioned stimulus (a cue from an internal or external event). Classical conditioning can explain both negative and positive emotional responses. For example, because of an earlier stressful medical event, a man experiences a negative emotional response (fear) when he hears his doctor’s voice. In contrast, a positive emotion, pleasure, is elicited when the same man hears his lover’s voice.

Elements of classical conditioning

The four elements of classical conditioning are the unconditioned stimulus, the unconditioned response, the conditioned stimulus, and the conditioned response. Pavlov’s classic studies illustrate these elements—dogs learned that the sound of a bell, rung in conjunction with presentation of food in the past, meant that food would appear in the present.

An unconditioned stimulus (e.g., the odor of food) automatically produces a reflexive, natural, unlearned, or unconditioned response (e.g., salivation). A conditioned stimulus is a neutral stimulus that produces a response following learning (e.g., the sound of the bell). A conditioned response is a behavior that is learned by an association made between a conditioned stimulus and an unconditioned stimulus (e.g., salivation in response to the bell).

Characteristics of classical conditioning

Response acquisition, extinction, spontaneous recovery, and stimulus generalization are characteristics of classical conditioning. In acquisition, the conditioned response (salivation in response to the bell) is acquired or learned. After learning has occurred, if the conditioned stimulus (the sound of the bell) is never again paired with the unconditioned stimulus (the presence of food), the conditioned response (salivation) decreases. This decrease and ultimate disappearance of the conditioned response is known as extinction. Sometimes, after extinction, the sound of the bell again generates salivation. This unexpected reoccurrence is called spontaneous recovery. Sometimes, a new stimulus such as a buzzer that resembles a conditioned stimulus (the bell) causes the conditioned response (salivation). This phenomenon is called stimulus generalization. A 2-year-old child who is afraid of nurses in white uniforms and cries when his grandmother comes to visit wearing a white jacket is an example of stimulus generalization.

Learned helplessness and imprinting

When an animal receives a series of painful electric shocks from which it is unable to escape, it learns, by classical conditioning, to make an association between the aversive stimulus (e.g., electric shock) and the inability to escape. Subsequently, the animal makes no attempt to escape when shocked or, in fact, when faced with any new aversive stimulus. Instead, the animal becomes hopeless and apathetic. This phenomenon has been termed learned helplessness. It is of interest that antidepressant treatment restores escape attempts in this animal model.

Learned helplessness in animals has been proposed as a model system for depression in humans. In this model, the person who has repeatedly tried and failed to control external events becomes hopeless, apathetic, and depressed (like the shocked animal) when faced with a new life stressor. Learned helplessness can help explain why children who repeatedly fail in school despite their best efforts eventually stop trying to do well and give up.

Imprinting is another phenomenon that has been observed in animal models. It is based on the concept of critical periods, limited intervals during which a developing animal is more sensitive to certain stimuli than at other times in its development. During the critical period for imprinting, the animal makes an association with and then follows the first thing it sees after birth or hatching. Although seen mainly in birds, imprinting has applications to human development, particularly for the critical period of attachment between an infant and its mother (see Chapter 1).

Operant Conditioning

In operant conditioning or trial-and-error learning, learning occurs because of the consequences to the individual of a previous behavior. Although the previous behavior may have occurred randomly at first, the consequence, occurring immediately after the behavior, determines whether or not the behavior continues.

Reinforcement and punishment

The likelihood that a behavior will occur is increased by reinforcement and decreased by punishment. Reinforcement can be positive or negative, and reinforcers can be primary or secondary. Positive reinforcement is the introduction of a stimulus that results in an increase in the rate of a behavior, and it can be praise, attention, or a tangible reward such as money. For example, if a child increases her studying behavior to earn money by receiving good grades, money is the positive reinforcer or reward that increases the desired studying behavior. It is of interest that money is a secondary reinforcer in that it is not intrinsically rewarding; rather, the need for money is learned. In contrast, a primary reinforcer such as food or warmth fulfills a biological need.

Negative reinforcement is the removal of an aversive stimulus that results in an increase in the rate of behavior. For example, if a child increases her studying behavior to avoid being scolded, active avoidance of an aversive stimulus (being scolded) increases the desired studying behavior.

Clinically, negative reinforcement is a major factor in adherence to medical advice. Patients rarely comply with a doctor’s advice to get a reward, but they often comply to avoid illness (a negative consequence). A patient who walks more to decrease the amount of antihypertensive medication that he or she requires is exercising because of negative reinforcement.

Punishment is the introduction of an aversive stimulus aimed at reducing the rate of an unwanted behavior. For example, if a child decreases her fooling around behavior after her mother scolds her, the scolding can be considered a punishment.

The introduction of a stimulus that seems aversive can actually increase the rate of unwanted behavior. For example, if a child increases her fooling around behavior after her mother scolds her, the scolding can be considered a positive reinforcer rather than a punishment because it increases the rate of the problematic behavior.

Extinction in operant conditioning is the gradual disappearance of a learned behavior when reinforcement (reward) is withheld. For example, if the mother’s attention is a reinforcer, the child eventually stops fooling around when that behavior is ignored by her mother. Characteristically, an initial increase in fooling around behavior occurs before it finally disappears.

Punishment versus extinction

Behavior is changed more effectively over the long term by rewarding or reinforcing individuals for desired behavior (positive reinforcement) or by not rewarding them for unwanted behavior (extinction), than by punishing unwanted behavior. Also, in contrast to extinction, which reduces behavior for a long time, the behavioral effects of punishment are more likely to be temporary.

One strategy that encourages extinction is time out. In this technique, an individual (usually a child) is temporarily removed from the social situation each time he or she misbehaves. Because during each time-out period the child receives no positive reinforcement (attention) for the undesirable behavior, that behavior ultimately becomes extinct.