Differential reinforcement effects in rats reared in enriched and impoverished environments

Comparison of the effects of environmental enrichment (EC) and impoverishment (IC) on learning in the rat is hindered by difficulty in distinguishing, experimentally, EC/IC differences in learning capacity per se from differences in performance-related variables such as sensory or motor ability, activity and motivation. Experiments are described which analyse EC/IC performance differences in a simple lever-press training procedure. In particular the hypothesis that EC and IC rats may be differentially reinforced by the same response-contingent events is examined. The data firmly support this hypothesis and possible explanations of the differential reinforcement effect are examined.