Extinction does not depend upon degradation of event memories

Abstract

Rescorla’s “event-memory” hypothesis posits that extinction decrement is due in part to a weakening of a central unconditioned stimulus (US) representation that is shared by all stimuli associated with a particular US. Thus, extinction of one stimulus conditioned to a US should decrease conditioned responding to a second stimulus that has been independently conditioned to the same US. In each of the present experiments, after excitatory conditioning to two stimuli separately, some rats experienced repeated nonreinforced presentations of one of the conditioned stimuli, while others were given no such exposures. Despite parametric variations across experiments, no reliable attenuation of suppression to the nonextinguished stimulus was evident during testing. Tests for suppression to the extinguished stimulus demonstrated a traditional extinction decrement. © 1984, Psychonomic Society, Inc.. All rights reserved.