Spontaneous recovery

Spontaneous recovery is a phenomenon of learning and memory which was first seen in classical (Pavlovian) conditioning and refers to the re-emergence of a previously extinguished conditioned response after a delay.

Spontaneous recovery is associated with the learning process called classical conditioning, in which an organism learns to associate a neutral stimulus with a stimulus which produces an unconditioned response, such that the previously neutral stimulus comes to produce its own, conditioned, response, often identical to that originally produced by the other, unconditioned stimulus. Although principles of classical conditioning had been noted by many Western scholars throughout the late nineteenth and early twentieth centuries, the discovery of classical conditioning is usually attributed to Ivan Pavlov, a nineteenth-century physiologist who came across classical conditioning while conducting research on canine digestion.