Spontaneous recovery from overexpectation.

In three Pavlovian magazine approach experiments, rats received conditioning of auditory and visual stimuli by pairing with a pellet. Then the stimuli received additional conditioning while presented in simultaneous compound and were tested either immediately or after a delay. The compound conditioning resulted in a decrement in responding to the individual stimuli (overexpectation). However, there was recovery of responding with the passage of time. These results suggest that the decrements produced by an overexpectation procedure share some properties with those produced by nonreinforcement.