Chlorpromazine-induced suppression in appetitive and avoidance responding as a function of shock intensity.

Abstract

This experiment investigated the role of shock intensity in determining the effects of chlorpromazine on appetitive and avoidance responses maintained concurrently in individual rats. Ss were trained and tested in a two-lever cage. Pressing one lever produced food according to a variable interval schedule of reinforcement; pressing the second lever at the onset of a warning signal avoided shock. After performance on this concurrent schedule had become stable, the effects of chlorpromazine in doses of 1.0, 2.0, and 4.0 mg/kg of body weight were observed at three intensities of shock: 0.5, 2.0, and 4.0 ma. The major results were as follows: (a) Chlorpromazine generated a dose-dependent decrease in both rate of appetitive responding and per cent avoidance responses. (b) Shock intensity did not significantly affect the rate of appetitive responses. (c) However, there was a significant Shock Intensity × Dosage interaction for avoidance responding. When compared to appetitive responding, chlorpromazine may effect a greater or lesser suppression in avoidance responding depending upon the intensity of shock maintaining the avoidance response.