Caffeine and impulsiveness in rats

Abstract

Two groups of rats maintained at 85% free-feeding weight (FFW), water-deprived 23 h daily, received 1-h access to either water or caffeine solution (0.5 mg/ml) and then 10–40 min later were tested for impulsiveness (choice of a small immediate reinforcer over a large delayed reinforcer) in a T maze. When they entered one goalbox, the rats would receive one pellet immediately, which we considered to be the impulsive choice. When they entered the other goalbox, the rats would receive six pellets after a delay of 15 sec, which we considered to be the self-control choice. Change scores revealed a statistically significant difference (p < .01) between groups, with the caffeine group making more impulsive choices. However, the absolute increase in impulsiveness was small. These results support research on the effects of caffeine on impulsive human behavior, which suggests that if caffeine does increase impulsiveness, the effect is weak. It is suggested that aversive stimulation may increase impulsiveness. © 1993, Psychonomic Society, Inc.. All rights reserved.