spontaneous recovery

Meaning: Spontaneous recovery is the reappearance of an extinguished conditioned response when the conditioned stimulus (CS) is presented again after a rest period. For example, a dog that stopped salivating to a bell after bell-without-food trials may salivate to the bell again later. The recovered response is usually weaker than the original and extinguishes quickly if the CS is again presented alone. It suggests extinction suppresses the response rather than erasing the learned association.

On the MCAT: Passages describe acquisition, then extinction, then a gap, then a test. A response-strength graph rises during acquisition, falls toward zero in extinction, jumps after the rest interval, and peaks below the acquisition level. Questions ask you to name the phase or infer that the association persisted. The same pattern is described in operant conditioning, where an extinguished behavior can reappear after a delay.

Common confusion: Spontaneous recovery needs no new pairing of the CS and the unconditioned stimulus (US); the response returns after time passes. If the CS and US are paired again, that is reacquisition, which usually goes faster than the original acquisition. It is also not stimulus generalization, which is responding to stimuli similar to the CS.