Stimuli preceding electric shock can acquire positive reinforcing properties.

Abstract

In a snugly fitting cage within apparatus designed for automatic administration of chemical, electrical and other stimuli, and continuous recording of head position and autonomic responses, male albino rats were presented fluctuating stimuli (auditory in one expt., visual in another) either before or during 30 or more tail shocks. Immediately after the last shock, photocells fluctuated the stimuli, i.e., presented reinforcement as long as the head was on the nonpreferred side. Duration of head position and frequency of moves increased significantly only in the Before group and only on the reinforced side. Max. effects occurred from 30 to 60 min. after the last shock. By this time most of the Before rats preferred the reinforced side. Explanations in terms of emotion, fear, punishment or repression seem more difficult than explanations in terms of Pavlovian conditioning of movements.