Rh responses reflect LH decisions, even when these decisions are in mutual conflict. A variant of this technique presents brief chimeras consisting of competing half stimuli around fixation, divided along the vertical meridian (Levy and Trevarthen 2). In this case, both the nature of the task and the response mode interact to select a behaviorally dominant hemisphere.
Bimanual responses facilitate interhemispheric cooperation for compatible stimuli in the two VFs even in the split brain. It seems that motor responses tend to be unified so that in the chronic condition the two hands do not respond in conflict with each other even when the two hemispheres make conflicting decisions.
The disconnected LH can be said to be generally dominant for several reasons. First, it is more likely than the RH to assume control over behavior in unlateralized situations. Second, it has better ipsilateral visual and tactile-kinesthetic sensory motor control than the RH. Third, LH performance is more stable and less sensitive to small task differences. Fourth, although each disconnected hemisphere is hemianopic with respect to ipsilateral half space and does not deny ipsilateral perceptual experience, the disconnected LH does routinely express disbelief of correct RH responses to left sensory field stimuli.
-The Split brain