Savings after extinction in conditioning of the rabbit’s nictitating membrane response

Abstract

The present experiments examined two forms of savings after the extinction of a conditioned response (CR) in the rabbit nictitating membrane preparation. Each experiment entailed three groups. First, a reacquisition (RAQ) group received initial conditioned stimulus-unconditioned stimulus (CS—US) acquisition, followed by CS-alone extinction, and then CS—US reacquisition with the same stimulus. Second, a cross-modal acquisition (CMA) group received initial acquisition and extinction with one stimulus but received its final stage of training with a stimulus from another modality. Third, a naive acquisition group (designated as REST) received only the final stage of CS—US training. In all three groups, tone and light were used as CSs in a counterbalanced fashion. In addition, the experiments tested whether the manipulation of contextual factors—namely, trial spacing and the number of trials per session—could influence the rates of acquisition in Groups RAQ and CMA after extinction. The experiments demonstrated that (1) reacquisition of the CR to the original CS was very rapid relative to Group REST, (2) cross-modal acquisition was also rapid relative to Group REST, and (3) in Group CMA, tests of the original CS showed concurrent recovery, which is a new phenomenon and is distinct from spontaneous recovery. However, the relative rates of acquisition after extinction appeared constant across the contextual manipulations. The results are discussed with respect to the relative stability of excitatory and inhibitory learning, as well as two alternative theories of savings after extinction.