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

The present experiments examined two forms of savings after the extinction of a conditioned response (CR) in the rabbit nictitating membrane preparati on. Each experiment entailed three groups. First, a reacquisition (RAQ) gro up received initial conditioned stimulus-unconditioned stimulus (CS-US) acq uisition, followed by CS-alone extinction, and then CS-US reacquisition wit h the same stimulus. Second, a cross-modal acquisition (CMA) group received initial acquisition and extinction with one stimulus but received its fina l stage of training with a stimulus from another modality. Third, a naive a cquisition group (designated as REST) received only the final stage of CS-U S training. In all three groups, tone and light were used as CSs in a count erbalanced fashion. In addition, the experiments tested whether the manipul ation 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 th e CR to the original CS was very rapid relative to Group REST, (2) cross-mo dal 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 pheno menon and is distinct from spontaneous recovery. However, the relative rate s of acquisition after extinction appeared constant across the contextual m anipulations. The results are discussed with respect to the relative stabil ity of excitatory and inhibitory learning, as well as two alternative theor ies of savings after extinction.