Extinction and Spontaneous Recovery

A classically conditioned response can be eliminated or extinguished by eliminating the predictive relationship between the signal and the reflex. This is accomplished by presenting the signal or CS while preventing the reflex from occurring. How can the reflex be prevented from occurring? One technique is to activate a behavior incompatible with the reflex. For example, a cat will be fearful of a box in which it has been given an electric shock. The cat can be given "therapy" later by feeding it in the box. That prevents the anxiety response, so the cat loses its fear of the box. Research like this led to a therapy called desensitization designed to eliminate fears and phobias. Desensitization was very successful as a therapy and marked the beginning of behavior therapy as a discipline.

If a CS occurs many times but the reflex is never activated, the organism learns that the signal no longer has the same meaning as before. The signal no longer predicts the activation of the reflex, and the conditional response disappears. This overall process is called extinction.

Landauer demonstrated extinction in his lecture. After establishing the conditional response (students jumping when he said, "NOW!") he extinguished it. He stuck up his arm periodically and shouted "NOW!" without firing the starter pistol. At first people continued to jump. However, as he repeated the action, shouting "NOW!" without firing the starter pistol, the response weakened. Eventually nobody jumped. By repeatedly giving the signal without firing the gun, he eliminated the predictive relationship between the conditional stimulus ("NOW!") and the CR or conditional response (the jump). Soon there was no conditional response. Extinction had occurred.

How does one extinguish a classical conditioned response? What is spontaneous recovery?

As time passes after extinction, a classically conditioned response typically recovers a bit of strength. This recovery takes place "spontaneously" without any additional training, so it is called spontaneous recovery. After Landauer first extinguished the startle response, he lectured on a different topic for 20 minutes. Then, without warning, he pushed his arm in the air and shouted "NOW!" (still without firing the pistol). Most of the crowd jumped again. Landauer had demonstrated spontaneous recovery.


Spontaneous recovery after the first extinction period

How does one completely extinguish a CR?

In order to completely extinguish a classically conditioned response, one must go through the extinction procedure repeatedly, eliminating spontaneous recovery each time it occurs. Incidentally, this diagram is idealized, which means it is unrealistically smoothed. A genuine record of behavior would never be this clean and simple.


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