Psychology, 5/e   Wortman, Loftus & Weaver
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CONCEPT 1: The Nature of Learning

Learning is involved in almost every phenomenon psychologists study, although it is neither observable nor measurable. Psychologists measure performance and infer that changes in performance reflect learning, although factors such as fatigue, emotion, motivation, health, and physical maturation can affect performance without affecting learning. Learning can take place without people being aware that they are learning something (Theme 3). Learning, thus, gives us the potential for a change in performance.

Learning is defined as a relatively permanent change in performance potential that arises from experience. Learning includes associative learning (learning that one event is associated with another). If the smell of hospitals makes you anxious because of a prior experience, then psychologists would say you have acquired a classically conditioned response. Classical conditioning is a very basic kind of learning in which a previously neutral stimulus comes to elicit an involuntary action or response.

Another type of associative learning is operant conditioning. This type of learning involves changing behavior because of the behavior’s consequences. For example, if the first time you walk by a construction site you get dirt all over your work clothes, on subsequent trips you will avoid going by the site in order to avoid getting dirty. Psychologists would call this a conditioned operant response.

Besides associative learning, there is also cognitive learning. This type of learning involves concept formation, schemas, theories, and other mental abstractions. Behaviorists argue that cognitions are too subjective for scientific study and that we should only study overt behavior.

CONCEPT II: Classical Conditioning

While studying salivation in dogs, a Russian physiologist named Ivan Pavlov discovered that dogs could anticipate their feeding time when the laboratory assistants entered the room. The dogs would begin to salivate to any stimulus that could be associated with food. This conditioning is sometimes called Pavlovian conditioning (classical conditioning). It involves reflex behavior in which a stimulus naturally produces (or elicits) an involuntary response. In classical conditioning, an originally neutral stimulus (one that elicits no response) is repeatedly presented just before the reflex stimulus or unconditioned stimulus (US). The neutral stimulus eventually becomes associated with the unconditioned stimulus-unconditioned response (the reflex response) pattern and soon comes to elicit that unconditioned response (UR), even in the absence of the unconditioned stimulus. This previously neutral stimulus becomes a conditioned stim ulus (CS), and the reflex response it produces is called the conditioned response (CR).

There are two necessary conditions for classical conditioning. One is contingency, or the likelihood that the CS signals the US. The other condition is contiguity, which refers to the timing of the CS and the US.

Generally, the CS must precede the US by only a short time for maximal conditioning to occur. This contingency situation is called forward conditioning. In trace conditioning, the CS reliably predicts the US, but the time between the two stimuli is greater, reducing the contiguity.

In simultaneous conditioning, the delay between the CS and the US is reduced to nothing. This type of conditioning is not as strong as forward conditioning. Backward conditioning involves presenting the US before the CS and is the least effective in establishing a conditioned response. The exception to this is found in some animals and humans. After eating food that produces illness, animals are quickly conditioned to avoid that food. Random presentation of CS and US is also ineffective in producing a CR. The CS and US contingency seems to depend upon the participant’s use of the CS to predict the US. When this relationship is unclear, conditioning is more difficult to establish, as Rescorla’s work demonstrates.

In classical conditioning, extinction is the slow weakening and eventual disappearance of the conditioned response. It is accomplished by no longer pairing the CS with the US. If an animal is removed from an experimental chamber for a while after its response has been extinguished and is then put back in, the extinguished response will recur. This is called spontaneous recovery.

Stimulus generalization is the expression of a learned response in a new but similar situation. For example, if your dog learns to run to the door to greet visitors when the doorbell rings, but then begins to run to the door when the telephone rings, then the dog is exhibiting stimulus generalization. When the dog learns to distinguish the two sounds, it is exhibiting stimulus discrimination. In general, the more similar two stimuli are, the more likely generalization will occur. Conversely, the more dissimilar two stimuli are, the more likely discrimination will occur. This is known as a generalization gradient. The technique of discrimination training, in which only certain stimuli (the discriminative stimuli) are associated with reinforcement, is used to train certain research animals. Together, generalization and discrimination work to help organisms respond to new situations in appropriate ways. Emotional responses are especially susceptible to classical conditioning, and difficult to extinguish.

John B. Watson found that classically conditioned fear could be diminished by counterconditioning, the pairing of a pleasant stimulus with a feared one in order to diminish the unpleasant reaction to the feared stimulus. A similar technique, called systematic desensitization, is now being used on phobias. A person is taught to relax and then gradually introduced to anxiety-producing situations, starting with mildly fear-arousing ones and working up to situations that, before desensitization, would have produced excessive anxiety. Classical conditioning can also be used to instill desired behaviors, as in the case of treating children who wet their beds.

CONCEPT III: Operant Conditioning

Using cats and puzzle boxes, Edward L. Thorndike examined another form of association learning which we now call operant conditioning. His law of effect states that responses which lead to satisfying consequences are strengthened and responses leading to unsatisfying consequences are weakened. B. F. Skinner proposed that the basic mechanism for controlling human behavior is the application of the principles of operant conditioning. According to this model, a consequence that increases the probability of the behavior that caused it is called a reinforcement (reward). A consequence that results in suppression of the causal behavior is called a punishment.

The term operant refers to emitted behavior. Operants produce different kinds of outcomes; desirable or undesirable. Positive reinforcement increases the frequency of response because that response is followed by a pleasant stimulus. Negative reinforcement also increases the frequency of a response, but it does so by removing a painful or unpleasant stimulus. Negative reinforcement can be used to establish escape learning, or learning a response that allows the organism to escape from an unpleasant situation, and avoidance learning, in which the organism learns a response which prevents a negative event from occurring.

Positive punishment decreases the frequency of a response by following the response with an unpleasant stimulus. The frequency of a behavior can also be reduced by removing a pleasant stimulus. This is known as negative punishment. Placing a child in time-out is an example of negative punishment.

Operant conditioning involves a cause-and-effect relationship between the response and the consequence. When an organism mistakenly assumes a contingency between a response and some consequences when in fact none exists, the result is called superstitious behavior.

Establishing a conditioned operant response is difficult because the response must first occur naturally before it can be reinforced and strengthened. The Skinner box (a cage with a lever that delivers a food reward when pressed) is one of many devices that control the presentation of rewards to experimental animals. It is useful in the study of operant conditioning because it allows easy measurement of an animal’s responses. Sometimes researchers who study operant responses choose to work with responses which often occur naturally because they are easier to train. When a participant does not typically make the response a psychologist wants to condition, a technique called shaping is used. Shaping involves reinforcement for closer and closer approximations of the desired behavior.

As in classical conditioning, extinction can occur in operant conditioning. A conditioned operant response that is no longer reinforced will gradually decrease in frequency. During the early stages of this extinction, the response becomes more forceful. Operant conditioning also exhibits the phenomenon of spontaneous recovery.

The key to maintaining an operant response is keeping up the reinforcement. Providing reinforcement on only some of the trials (partial reinforcement) results in higher response and greater resistance to extinction. This phenomenon is known as the partial reinforcement effect. Reinforcement can be applied in many patterns or schedules of reinforcement. Continuous reinforcement, in which every response is followed by a reward, is usually most effective for establishing a new behavior. There are four types of partial schedules. A fixed-ratio (FR) schedule provides a reward each time the participant makes a specified number of responses. A fixed-interval (FI) schedule rewards the first response made after a specified period of time has elapsed. A fixed-interval schedule usually results in a relatively low frequency of responses. There is also a tendency for there to be very few responses immediately following reinforcement. This is known as the po streinforcement pause. As time passes and the reinforcement approaches, the frequency of the activity increases. The pattern of high rates of response prior to reinforcement and low rates of response after reinforcement is known as scalloping.

Variable-ratio (VR) schedules and variable-interval (VI) schedules are like their fixed counterparts, except the number of responses or amount of elapsed time varies randomly from trial to trial. Variable schedules are, thus, unpredictable, and therefore tend to produce high response rates and persistent behaviors.

Stimulus control refers to the situation in which the reinforcement schedule operates only in the presence of a particular stimulus--for example, when a red light is lit. Consequently, the participant learns to respond only when the stimulus is present. This stimulus is a discriminative stimulus because it allows the participant to distinguish, or discriminate, this stimulus from others.

Primary reinforcers, such as food or water, satisfy a basic biological need. Secondary reinforcers, such as praise or money, signal that a primary reinforcer is forthcoming. Learning a sequence of behaviors that eventually ends with primary reinforcement is called chaining.

CONCEPT IV: Observational Learning

Learning can occur simply by watching the behavior of others. This type of learning is known as observational learning.

The social learning theory states people can learn by observing other people’s behavior even in the absence of a reinforcer. Albert Bandura states that reinforcement is more important in getting people to perform a behavior rather than to learn it. Bandura believes that humans can be influenced by the consequences that others receive for their actions. Bandura calls these "secondhand" consequences vicarious reinforcement and punishment. Our inner reactions can also influence our behavior through intrinsic reinforcement and punishment. Bandura points out that no reward or punishment is necessary for learning to occur. Some studies have shown that children may learn and imitate behavior with no external inducements.

People form abstract representations of behavior known as schemas. These schemas actively guide our own thoughts and behaviors (Theme 4). Television is one of the most powerful sources of behavior influence. People form social stereotype schemas from watching television programs. These schemas can be good or bad, depending on the message they deliver.

Although learning and cognition are often treated as separate subjects, they are both intertwined. While behaviorists focus on overt actions, cognitivists are more concerned with getting "inside the head" of those they are studying. Social learning theory combines cognition and learning into one model.

CONCEPT V: Practical Applications of Learning Principles

Operant conditioning techniques have been applied to humans in the form of behavior modification. Behavior modification is the conscious use of operant conditioning principles to change human behavior. Today, behavior modification is also known as contingency management. Reward programs often consist of token economies, in which tokens (such as poker chips that can later be exchanged for other reinforcers) are earned by demonstrating appropriate behavior.

Learning theory can be applied to suppress maladaptive behaviors in a technique known as aversive conditioning. In this type of therapy, an undesired activity is paired with an unpleasant stimulus. This therapy has some limitations. It is fairly temporary and can cause emotional disturbances. Finally, this therapy and the circumstances that surround it can come to be aversive stimuli to be escaped or avoided. Furthermore, aversive conditioning does not indicate what the desirable behavior would be. Consequently, it is usually best used in conjunction with reinforcement of appropriate behavior.

CONCEPT VI: Biological Considerations in Associative Learning

If an organism is not biologically disposed to learn a behavior, such learning is difficult to accomplish. The biological or genetic predisposition to learn is called prepared learning. Keller and Marion Breland discovered another interesting phenomenon while trying to train animals to perform unusual tricks. At first, certain animals would perform the trick as desired, but after a while the animal reverted to a more natural behavior. When a trained animal reverts to genetically based behaviors, the reversion is called instinctive drift.

CONCEPT VII: Studying Learned Taste Aversions

A series of experiments conducted by Garcia demonstrates that some stimulus-response associations are learned much more easily than others. Rats, for instance, associated the taste of a substance with physical illness and the visual cues in a situation with electric shock, but they did not associate visual cues with illness or the taste of a substance with electric shock. Garcia explained this tendency as a function of the evolutionary history of the species: natural selection has favored a nervous system that allows easy learning of contingencies crucial to survival. Garcia had discovered prepared learning.

Robert Koelling furthered this research by pairing stimuli with various aversive conditions. He found that rats learned certain associations of paired stimuli more readily than others. This finding was contrary to Pavlov’s assertion that all stimuli were equally conditionable.

Ilene Bernstein has found that cancer patients associate foods eaten prior to chemotherapy with the nausea caused by the therapy; so novel foods introduced prior to therapy can serve as scapegoats for the nausea association. Pretherapy fasting also prevents the food associations. The goal of these applications is to prevent unnecessary weight loss.

Taste aversion is considered to be a dramatic, but normal example of classical conditioning. The strength of learning taste aversion has obvious evolutionary advantages.

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