Chlorpromazine effects on behavior under escape and fixed-time delivery of shock

Chlorpromazine has typically been found to reduce responding maintained by negative reinforcement. In squirrel monkeys, however, it has been shown to increase manipulative responses that occur just prior to shock presented under a fixed-time schedule. The present study compared chlorpromazine effects on behavior of rats under a fixed-time schedule of shock delivery and a schedule involving escape from shock. In all conditions, shock was delivered to the tail of rats held in partial restraint, and the response measured was displacement of a panel positioned directly in front of the rat's nose. The escape and fixed-time schedules generated similar temporal patterns and rates of responding under both schedules, and had no differential effect on the temporal distribution of responses within the shock interval.