A light overshadowed a noise in a conditioned fear paradigm. There was less fear of the noise if it had been compounded with the light when paired with shock than if the noise alone had been paired with shock. However, a high level of fear to the noise was found in rats that subsequently underwent extinction of the fear conditioned to the light. This finding suggests that overshadowing is not due just to the noise not being associated with shock; it suggests that overshadowing is due in part to a failure of the noise-shock association to be expressed in behavior.

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