Robert P. O'Shea

Department of Psychology, University of Otago, Dunedin, New Zealand

Visual Consciousness in Split-Brain Observers

A split-brain observer has had the corpus callosum, which normally joins the two cerebral hemispheres, cut to relieve epilepsy. This surgery does help control the epilepsy, but has the fascinating side effect of creating separate consciousnesses in the two brain hemispheres. How different is each hemisphere's experience of the visual world, each hemisphere's visual consciousness? I argue that the continuity of the visual world demands similar visual consciousness in the two hemispheres. I report on research using an intriguing phenomenon of visual consciousness, binocular rivalry. Binocular rivalry occurs when different stimuli are presented to the two eyes: one stimulus disappears for a few moments, then it reappears and the other stimulus disappears. These alternations in visibility continue for as long as one cares to look. Split-brain observers report qualitatively similar rivalry from each hemisphere, although alternations are slower from the left hemisphere than from the right. The difference between hemispheres may arise from differences in response criteria. The similarity between hemispheres is consistent with similar visual consciousnesses. I consider the implications of these results for theories of binocular rivalry in intact-brain observers.

This page was last updated on 16 Feb 2001.

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