Split-brain basics: relevance for the concept of one's other mind.

Frontal and horizontal sections of the cerebrum make plain that with a few exceptions (pineal, pituitary) all structures are paired. Hemicerebrectomy has made clear that only one member of the hemispheric pair suffices to sustain the sentiments, emotions, memories, and intentions both conscious and unconscious that we call in the aggregate, mind. That the anatomical duality can sustain a duality of mentation is evident from not only the split-brain results in all species examined but also the results of appropriate testing of anatomically intact individuals. There is no physiological evidence for a plurality of mind beyond duality. Psychoanalytic views of mind can benefit from revision in the light of the split-brain studies. But such revisions seem slight compared with improvements needed in the views prevalent among most other psychologic and philosophic theorists.