Spontaneous recovery occurs when

• A. The conditioned response reappears after a rest period when the conditioned stimulus is presented again
• B. The conditioned response weakens after extinction
• C. The reinforcement schedule changes from variable to fixed
• D. The response becomes more discriminated

Answer: (A)

Spontaneous recovery is a phenomenon in classical conditioning where, after the conditioned response has been weakened or eliminated through extinction, a rest period is followed by the reappearance of the conditioned response when the conditioned stimulus is presented again. This shows that the original association isn’t erased during extinction; it’s temporarily suppressed and can re-emerge with a break in training. The reappearance is usually weaker than the initial response and fades again with time if training conditions aren’t reinforced.

The other ideas don’t fit as well: extinction describes the CR weakening after repeated CS-alone trials; changing reinforcement schedules is about how rewards are delivered rather than the recovery of a response after a break; discrimination refers to tuning responses to specific cues rather than their reappearance after rest.