The effects of dark isolation on the performance of a white-black discrimination task in the rat.

Four experiments were performed on rats using a white-black discrimination task. In Exp. 1 the animals that were isolated in darkness for four hours after each learning trial performed with fewer errors than the animals that spent the same posttrial periods in enriched environments in groups. In Exp. 2 training was carried further and retention after 10 days was investigated. The isolated animals again performed with fewer errors. In Exp. 3 a control was added to the Isolated and Enriched conditions. Animals in the control group were returned to their home cages after each training trial. No difference was found between Enriched and Control animals. In Exp 4 Dark-Isolated, Light-Isolated, Dark-Crowded and Light-Crowded groups were used. The performance of the two Dark-treated groups was superior to that of the Light-treated groups. The findings are discussed with reference to interference and consolidation theory.