VARIATIONS IN ATTENTIONAL BIAS OF THE DISCONNECTED CEREBRAL HEMISPHERES

The research presented in this paper investigates differences in the h emispheric control of attention. In particular, the contribution of en vironmental as well as egocentric co-ordinates to the speed of respons es to attended visual stimuli is considered. Five patients with comple te section of the corpus callosum were tested under conditions that al low hemispheric sensitivity to environmental and egocentric co-ordinat es to be examined separately. We conclude that each hemisphere can dir ect attention in the contraversive direction in both egocentric and en vironmental co-ordinate space. Additionally, right-hemisphere dominanc e for maintenance of alertness is supported. These results are discuss ed in the context of neurophysiological data and current theories of a ttention.