Interhemispheric interference during word naming

Abstract

The hypothesis that the use of two hemispheres as receiving stations for information, rather than just one hemisphere, decreases interference between items, and improves performance, was tested by requiring subjects to identify four words simultaneously projected to one visual field (Unilateral-single hemisphere presentation) or divided between two visual fields (Bilateral-bihemispheric presentation.) In Experiment I, words projected to different hemispheres were incorrectly “blended” into a single response as frequently as words projected to a single hemisphere. In Experiment II, subjects were told that half of the display was irrelevant. Irrelevant words which were projected to a different hemisphere than the relevant words were incorrectly named as often as when all four words were projected to the same hemisphere. In addition, overall performance during Bilateral-bihemispheric presentations did not exceed that during the better of the two Unilateral-single hemisphere presentations, not only when naming was required (Experiments I and II), but even when only recognition was required (Experiment III). This demonstrates that division of inputs between the hemispheres does not always improve performance.