Dr. Fredric Schiffer is a psychiatrist and teaches the theory and practice of Dual-Brain Psychology. In his book, Of Two Minds he describes how after reviewing the split-brain studies of the 1960s, patients who had their corpus callosums cut, manifested two separate minds and personalities!

He believes that most of us have two minds, one linked to each hemisphere; one that is more mature, reasonable, and present orientated, and one that is more childlike, emotional, and holds traumatic experience. He shows how this explains changes in mood and personality where someone might seem like two different people.