Able to name, unable to compare: the visual abilities of a posterior split-brain patient

A patient with a lesion of the posterior half of the corpus callosum correc tly named simple (e.g. colors) and complex (e.g. faces) stimuli whether pre sented to one or both hemifields. Although proficient at these tasks, and a lso able to make same/different judgements for stimuli within an hemifield, he failed dramatically when required to compare stimuli between the two he mifields. These results indicate that, while the posterior portion of the c orpus callosum may not be essential for naming visual stimuli, it is essent ial for comparing stimuli between the two visual fields. (C) 2000 Lippincot t Williams & Wilkins.