Extinction (psychology)

Extinction is observed in both operantly conditioned and classically conditioned behavior. When operant behavior that has been previously reinforced no longer produces reinforcing consequences the behavior gradually stops occurring. In classical conditioning, when a conditioned stimulus is presented alone, so that it no longer predicts the coming of the unconditioned stimulus, conditioned responding gradually stops. For example, after Pavlov's dog was conditioned to salivate at the sound of a bell, it eventually stopped salivating to the bell after the bell had been sounded repeatedly but no food came. Many anxiety disorders such as posttraumatic stress disorder are believed to reflect, at least in part, a failure to extinguish conditioned fear.