Binocular rivalry in split-brain observers.

During binocular rivalry, visual perception switches between a stimulus viewed by one eye and a different stimulus viewed by the other. We studied rivalry in split-brain observers to test two explanations. Rivalry could reflect switching of activity between the cerebral hemispheres, or switching by a structure in the right frontoparietal cortex. From these two theories, we predict no rivalry when stimuli are presented to a split-brain observer's left hemisphere. Yet we found similar rivalry from the left and right hemispheres of the split-brain observers, consistent with switchings being mediated by low-level processes within each hemisphere.