Hemispheric differences in a categorization matching task.

Abstract

The laterality difference in the execution of the higher-order cognitive task, categorization utilizing a superordinate concept, was examined. The subjects decided whether the two stimuli serially presented in the right or left visual field came under an identical category. In Exp. I, outline drawing stimuli were used and the RVF condition superiority in latency in the "same" response and LVF condition superiority in the "different" responses were demonstrated. These results were similar to those in the previous physical matching task and suggested that a superordinate concept was not in use to execute the present task. In Exp. II, vertically written verbal stimuli were used and the RVF condition superiority in both the "same" and the "different" responses were demonstrated. These results would suggest the superiority of the left hemisphere in the higher-order cognitive tasks.