Effect of Chlorpromazine on Discrimination and Reversal Learning in the White Rat

Abstract

The literature concerning the effects of chlorpromazine on basic psychological processes has been concerned primarily with problems involving the acquisition or retention of conditioned emotional behavior (5, 6) . The present report deals with a study of the effects of two dose levels of chlorpromazine on speed of learning a black-white discrimination, a learning problem which may be considered to be non-emotional as compared, for example, with gridshock motivated responses. METHOD Sabjects.-30 male albino rats of the Wistar strain between 90 and 100 days of age were divided into three groups and handled for 15 to 20 min. daily for 10 days prior to drug administration. Throughout the study Ss were fed 10 mg. per day of powdered Purina Dog Chow mixed 1:2 with water by weight at 10:OO p.m. For three days prior to the learning trials animals were in the apparatus for one-half hour where food was available in the goal compartments. Apparatu.r.-A Y-maze with a start box of 8 in., approach of 23 in., and choice alleys of 22 in. was used. It was 5 in. wide and 8 in. deep throughout. The entire maze was painted grey and was covered with hardware cloth which was hinged over the start and goal boxes. One door was white, the other black, with their positions varied during each day's trials following Hilgard ( 7 ) . The correct door could swing free and the incorrect door was blocked. The reward ( . l mg. of wet mash) was placed at the rear of the appropriate goal box. Light was provided by a 40-w bulb 10 in. above the choice point.