Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Arthur G. Snapper

Second Advisor

Dr. Frederick P. Gault

Third Advisor

Dr. M. Ray Denny

Access Setting

Masters Thesis-Open Access


Three groups of rats learned a black-white discrimination in a Grice box. All subjects were reinforced with food pellets for correct choices. No-Retrace subjects were confined in the negative goal box after errors. Retrace subjects were allowed to withdraw after errors from the negative goal box to the choice point or start box. Take-Out subjects were manually removed from the goal box during errors immediately after inspecting the empty food dish. All subjects were trained to a criterion and then reversal training was instituted. Retrace subjects learned the original discrimination significantly slower than either No-Retrace or Take-Out subjects, which did not differ from one another. This effect was replicated when Retrace subjects also took more trials to learn the reversal. Apparently, post-nonreinforcement stimuli that Retrace subjects encountered retarded the discrimination learning.