Some effects of non-reinforcement in split-brain monkeys.

Some effects of non-reinforcement in split-brain monkeys. PHYSIOL. BEHAV. 6 (6) 703-706, 1971.-Three experienced split-brain monkeys were taught a visual pattern discrimination in one eye hemisphere and shifted to an FR-2 schedule of reinforcement. The opposite hemisphere was then allowed to view the discrimination on thenon-reinforced trials. Under this condition the untrained hemisphere began disrupting the performance of the trained hemisphere. This was reflected in an increase in response latencies and number of errors. In a second experiment, both hemispheres independently learned the same discrimination on FR-2. Again, a disruption in responding occurred when one hemisphere viewed the discrimination only on the non-reinforced trials. The results suggest that reinforcement aids learning by eliminating the disruptive responses of non-reward. Also the data gives some indication of the brain processes involved in extinction and secondary reinforcement. Split-brain Learning Extinction Secondary reinforcement Unity of consciousness Frustration IN AN earlier report [8] it was found that an untrained hemisphere of a slit-brain monkey could learn a visual discrimination by observing the errorless performance of the task by the opposite hemisphere. These results indicated that a half brain need not experience errors or make overt responses in order to learn a discrimination. Further consideration of the minimal conditions for learning drew attention to the role of reinforcement. In that experiment, liquid reinforcement was experienced by both hemispheres on every trial. In the present study, in an effort to determine the role of reinforcement, one hemisphere was trained on a visual discrimination task and placed on an FR-2 schedule of reinforcement. After steady, near perfect performance was acheived the opposite hemisphere was allowed to view the discrimination on the non-reinforced trials, while the other hemisphere was responding to a discrimination task in which every other trial was reinforced. Contrary to our expectation there was no evidence of learning. Rather the half brain that observed the discrimination only on the non-reinforced trials began to disrupt the ongoing behavior of the opposite hemisphere. METHOD Three monkeys (Maccaca mulatta) were used in this study. All had undergone midline section of the corpus callosum, anterior and hippocampal commissures and optic chiasm [5]. The monkeys were maintained in specially designed restraining chairs throughout the training and testing procedures. During an experimental session, the chair was placed in a soundproof box facing a response panel. Vision was restricted on three sides by a Plexiglas shield, allowing the panel to be viewed only …