Effects of increasing the interstimulus interval during classical conditioning of the albino rabbit.

Abstract
Classical nictitating membrane conditioning in rabbits at an interstimulus interval (ISI) of 2,500 msec. was examined as a function of 3 training procedures. Group C2500 (N = 15) received 22 71-trial sessions at an ISI of 2,500 msec; Group C400 (N = 15) received 17 sessions at an ISI of 400, followed by 5 at an ISI of 2,500 msec; Group E400 (N = 14) received 5 sessions at 400, 2 each at, successively, 650, 900, 1,200, 1,500, 1,800, and 2,150, and the final 5 at 2,500 msec. In the last 5 sessions, probability was lowest, and latency and latency SD were largest, in Group C2500; and probability was highest, and latency and latency SD smallest, in Group C400.