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A broad term to describe techniques used by psychologists to study the process of learning.

Psychology has often been defined as the study of behavior. As such, psychologists have developed a diverse array of methods for studying both human and animal activity. Two of the most commonly used techniques are classical conditioning and operant conditioning. They have been used to study the process of learning, one of the key areas of interest to psychologists in the early days of psychology. Psychologists also attach considerable significance to conditioning because it has been effective in changing human and animal behavior in predictable and desirable ways.

The Russian physiologist Ivan Pavlov developed the principles of classical conditioning. In his Nobel Prize-winning research on the digestive processes, he placed meat powder in the mouths of his research animals and recorded their levels of salivation. At one point,

During potty training, children are conditioned to associate the urge to urinate with sitting on the toilet. (Photo by Elizabeth Hathon. Stock Market. Reproduced with permission.)

he noticed that some of his research animals began to salivate in the absence of food. He reasoned that the presence of the animal caretakers led the animals to anticipate the meat powder, so they began to salivate even without the food.

When classical conditioning occurs, an animal or person initially responds to a naturally occurring stimulus with a natural response (e.g., the food leads to salivation). Then the food is systematically paired with a previously neutral stimulus (e.g., a bell), one that does not lead to any particular response. With repeated pairings, the natural response occurs when the neutral stimulus appears.

Pavlovian (i.e., classical) conditioning influenced psychologists greatly, even though Pavlov himself was skeptical of the work psychologists performed. In the United States, John Watson, the first widely known behaviorist, used the principles of classical conditioning in his research. For example, in a widely cited study, Watson tried to develop a classically conditioned phobia in an infant.

Although classical conditioning became the dominant Russian model for the study of behaviorism, another form of conditioning took hold in the United States. This version, which became known as operant or instrumental conditioning, initially developed from the ideas of the psychologist Edward Thorndike. Thorndike began his psychological research by studying learning in chickens, then in cats. Based on the problem solving of these animals, he developed the Law of Effect, which in simple form states that a behavior that has a positive outcome is likely to be repeated. Similarly, his Law of Exercise states that the more a response occurs in a given situation, the more strongly it is linked with that situation, and the more likely it is to be repeated in the future.

Operant conditioning was popularized by the psychologist B.F. Skinner. His research and writings influenced not only psychologists but also the general public. Operant conditioning differs from classical conditioning in that, whereas classical conditioning relies on an organism's response to some stimulus in the environment, operant conditioning relies on the organism's initiating an action that is followed by some consequence.

For example, when a hungry person puts money into a vending machine, he or she is rewarded with some product. In psychologists' terms, the behavior is reinforced; in everyday language, the person is satisfied with the outcome. As a result, the next time the person is hungry, he or she is likely to repeat the behavior of putting money into the machine. On the other hand, if the machine malfunctions and the person gets no food, that individual is less likely to repeat the behavior in the future. This refers to punishment.

Any time a behavior leads to a positive outcome that is likely to be repeated, psychologists say that behavior has been reinforced. When the behavior leads to a negative outcome, psychologists refer to it as punishment. Two types of reinforcement and punishment have been described: positive and negative.

Positive reinforcement is generally regarded as synonymous with reward: when a behavior appears, something positive results. This leads to a greater likelihood that the behavior will recur. Negative reinforcement involves the termination of an unpleasant situation. Thus, if a person has a headache, taking some kind of pain reliever leads to a satisfying outcome. In the future, when the person has a headache, he or she is likely to take that pain reliever again. In positive and negative reinforcement, some behavior is likely to recur either because something positive results or something unpleasant stops.

Just as reinforcement comes in two versions, punishment takes two forms. Psychologists have identified positive punishment as the presentation of an unpleasant result when an undesired behavior occurs. On the other hand, when something positive is removed, this is called negative punishment. In both forms of punishment, an undesired behavior results in a negative consequence. As a result, the undesired behavior is less likely to recur in the future.

Many people mistakenly equate negative reinforcement with punishment because the word "negative" conjures up the idea of punishment. In reality, a situation involving negative reinforcement involves the removal of a negative stimulus, leading to a more satisfying situation. A situation involving punishment always leads to an unwanted outcome.

Beginning with Watson and Skinner, psychology in the United States adopted a behavioral framework in which researchers began to study people and animals through conditioning. From the 1920s through the 1960s, many psychologists performed conditioning experiments with animals with the idea that what was true for animals would also be true for humans. Psychologists assumed that the principles of conditioning were universal. Although many of the principles of learning and conditioning developed in animal research pertain to human learning and conditioning, psychologists now realize that each species has its own behavioral characteristics. Consequently, although the principles of conditioning may generalize from animals to humans, researchers must consider the differences across species as well.

Further Reading

Mackintosh, N. J. Conditioning and Associative Learning. New York: Oxford University Press, 1983.

Walker, James T. The Psychology of Learning. Upper Saddle River, NJ: Prentice-Hall, 1996.

Additional topics

Psychology EncyclopediaLearning & Memory