Overtraining Effects on Reversal and Nonreversal Discrimination Shifts with a Continuously Reinforced Free Operant
Rats were trained on a single-stimulus, successive discrimination in a free operant situation with continuous reinforcement of responding to S+. Ss were given 0, 4, or 8 days of overtraining (OT) after reaching the discrimination criterion. Half of the Ss were given a reversal shift (RS) and half a nonreversal shift (NRS). An irrelevant stimulus dimension was present at all times in Exp. 1, and it was absent in Exp. 2. OT did not affect RS or NRS learning in either experiment. NRS learning was faster than RS learning. These results were contrasted with other studies which have reported that OT facilitated RS learning and impeded NRS learning. Certain theoretical interpretations of discrimination learning, particularly Sutherland's treatment of centrally mediated attentional mechanisms, were critically discussed in light of the present findings.