Hemispheric lateralization of the decisional stage in choice reaction times to visual unstructured stimuli

Simple manual RTs to lateral visual stimuli were found to be faster in uncrossed than in crossed anatomical conditions. Neither hand nor hemifield effects were found. By contrast significant asymmetries were found in Choice RTs involving both hemispheres, even in uncrossed condition. The field effect was marked when the responding hand was the right but insignificant when the responding hand was the left. The data seem consistent with a model which assumes the location of the decisional structures in the left hemisphere.