Taking the high road on subcortical transfer

Kingstone and Gazzaniga (1995) presented conceptually ambiguous word pairs, such as HOT–DOG, to a split-brain patient. Each hemisphere received only one of the words. With one hand, the patient drew the word pairs literally (e.g., a dog panting in the heat) but never drew the emergent object (e.g., a frankfurter in a bun). This finding suggested that each hemisphere has a remarkable capacity to switch control of the same response hand. The present study tested this idea directly. The results indicated that each hemisphere could draw words with either the contralateral or the ipsilateral hand. This capacity of disconnected hemispheres to switch control of the response hand can create the illusion of subcortical transfer of higher-order information and must be taken into account in studies with split-brain patients.