Spontaneous recovery (learning)

In classical conditioning, spontaneous recovery or resurgence in operant conditioning, is the reemergence of a conditioned response after the conditioning stimulus has been extinguished. Spontaneous recoveries tend to yield somewhat muted responses in which exctintion occurs more readily.

For example, a dog's conditioned response of salivating to a bell will often, after it has been extinguished, reappear when the dog later hears the sound of a bell. This phenomenon is known as "spontaneous recovery."