Overview of Extinction in Psychology

Extinction may occur if behaviors are not reinforced
Extinction in Psychology. Shestock / Blend Images / Getty Images

What could cause a person or animal to stop engaging in a previously conditioned behavior? Extinction is one explanation. In psychology, extinction refers to the gradual weakening of a conditioned response that results in the behavior decreasing or disappearing. In other words, the conditioned behavior eventually stops.

For example, imagine that you taught your dog to shake hands. Over time, the trick became less interesting.

You stop rewarding the behavior and eventually stop asking your dog to shake. Eventually, the response becomes extinct, and your dog no longer displays the behavior.

Causes of Extinction and When It Occurs

In classical conditioning, when a conditioned stimulus is presented alone without an unconditioned stimulus, the conditioned response will eventually cease. For example, in Pavlov's classic experiment, a dog was conditioned to salivate to the sound of a bell. When the bell was repeatedly presented without the presentation of food, the salivation response eventually became extinct.

In operant conditioning, extinction occurs when a response is no longer reinforced following a discriminative stimulus. B. F. Skinner described how he first observed this phenomenon:

"My first extinction curve showed up by accident. A rat was pressing the lever in an experiment on satiation when the pellet dispenser jammed. I was not there at the time, and when I returned I found a beautiful curve. The rat had gone on pressing although no pellets were received. . . . The change was more orderly than the extinction of a salivary reflex in Pavlov's setting, and I was terribly excited. It was a Friday afternoon and there was no one in the laboratory who I could tell. All that weekend I crossed streets with particular care and avoided all unnecessary risks to protect my discovery from loss through my accidental death."

Examples of Extinction

Let's take a closer look at a few more examples of extinction.

Imagine that a researcher has trained a lab rat to press a key to receive a food pellet. What happens when the researcher stops delivering the food? While extinction will not occur immediately, it will after time. If the rat continues to press the key but does not get the pellet, the behavior will eventually dwindle until it disappears entirely.

Conditioned taste aversions can also be affected by extinction. Imagine that you ate some ice cream right before getting sick and throwing it up. As a result, you developed a taste aversion to ice cream and avoided eating it, even though it was formerly one of your favorite foods.

One way to overcome this reluctance would be to expose yourself to ice cream, even if just the thought of eating it made you feel a little queasy. You might start by taking just a few small tastes over and over again. As you continued to eat the food without getting sick, your conditioned aversion would eventually diminish.

Extinction Doesn't Mean It's Gone Forever

If the conditioned response is no longer displayed, does that really mean that it's gone forever? In his research on classical conditioning, Pavlov found that when extinction occurs, it doesn't mean that the subject returns to their unconditioned state. Allowing several hours or even days to elapse after a response has been extinguished can result in spontaneous recovery of the response. Spontaneous recovery refers to the sudden reappearance of a previously extinct response.

In his research on operant conditioning, Skinner discovered that how and when a behavior is reinforced could influence how resistant it was to extinction.

He found that a partial schedule of reinforcement (reinforcing a behavior only part of the time) helped reduce the chances of extinction. Rather than reinforcing the behavior each and every time it occurs, the reinforcement is given only after a certain amount of time has elapsed or a certain number of responses have occurred. This sort of partial schedule results in behavior that is stronger and more resistant to extinction. 

Factors That May Influence Extinction

A number of factors can influence how resistant a behavior is to extinction. The strength of the original conditioning can play an important role.

The longer the conditioning has taken place and the magnitude of the conditioned response may make the response more resistant to extinction. Behaviors that are very well established may become almost impervious to extinction and may continue to be displayed even after the reinforcement has been removed altogether.

Some research has suggested that habituation may play a role in extinction as well. For example, repeated exposure to a conditioned stimulus may eventually lead you to become used to it, or habituated. Because you have become habituated to the conditioned stimulus, you are more likely to ignore it and it's less likely to elicit a response, eventually leading to the extinction of the conditioned behavior.

Personality factors might also play a role in extinction. One study found that children who were more anxious were slower to habituate to a sound. As a result, their fear response to the sound was slower to become extinct than non-anxious children.

Sources:

Coon D, Mitterer JO. Psychology: A Journey. 5th ed. Wadsworth Publishing; 2013.

Pavlov (1927) PI. Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral CortexAnnals of Neurosciences. 2010;17(3):136-141. doi:10.5214/ans.0972-7531.1017309.

Skinner BF. A Case History in Scientific Method. American Psychologist. 1956;11:221-233.

Skinner BF. The Shaping of a Behaviorist: Part Two of an Autobiography. New York: Alfred A. Knopf; 1979.