Effects of overtraining on reversal learning by rats in concurrent and single discriminations

Two experiments examined the whole-partial effect of overtraining in concurrent discriminations and assessed the effect against single discrimination training in rats. In Experiment 1 overtraining facilitated reversal in Group W, in which rats were given concurrent training on two simultaneous discrimination tasks (A and B) in original learning before both tasks were reversed. By contrast, overtraining delayed reversal in Group P, in which animals were given the same training as in Group W in original learning, but only Task A was reversed. After overtraining, Group W reversed more rapidly than Group P. Without overtraining, Group P reversed more rapidly than both Group W and Group C, in which animals were trained only on Task A before this task was reversed. Experiment 2 investigated the effects of overtraining on the reversal of a successive discrimination in Groups W, P, and C. In addition, animals in a further group, Group S, received the same concurrent training as Group W before Task B was omitted and Task A reversed. Overtraining facilitated reversal in Groups W, C, and S but delayed it in Group P. After overtraining, Group W reversed more rapidly than Groups P, S, and C. Both Groups S and C also reversed more rapidly than did Group P. Without overtraining, Group P reversed more rapidly than Groups W, S, and C. There were no significant differences in reversal performance among Groups W, S, and C. These findings indicate that the effects of overtraining on reversal learning in concurrent discriminations differ from those observed in single discriminations.