Reversal learning in rats as a function of percentage of reinforcement and degree of learning.

Abstract

An experiment was performed investigating the effect of percentage reinforcement and degree of overlearning on reversal learning in rats. 168 female albino rats, 75-80 days old, were run in a black-white discrimination task according to a 2 x 4 orthogonal design. Acquisition was under 1 of 2 percentages of reinforcement[long dash]100% and 50%. Upon reaching criterion the groups were divided into 4 subgroups receiving 0, 70, 140, or 280 trials overlearning. Following overlearning, reversal learning was begun. Acquisition level was also controlled. Results showed that following 50% reinforcement, there is an inverse relationship between the number of overlearning trials and ease of reversal learning. Following 100% reinforcement, no effect due to over-learning was found. Reversal was easier following 100% than following 50% reinforcement. It was concluded from the reversal results that at least 2 factors are required to explain the partial reinforcement effect and the overlearning reversal effect.