THE HUMAN SPLIT BRAIN-SIGNIFICANCE

The human split brain studies had a number of interesting results. Chief among these was the confirmation, simultaneously and in combination, of two conclusions which had been reached previously and separately on other grounds.

One conclusion is usually called complementary hemispheric specialization (CHS). This had already been inferred fron the results of lateralized lesions (largely through the work of Oliver Zangwill of England and Henri Hecaen of France together with their colleagues, most notably Brenda Milner of Montreal. This conclusion was subsequently supported by various other kinds of evidence(see Bogen refs OSOB I 1969, Education 1975,Dual brain,1985). The importance of the split brain evidence for CHS led to Roger Sperry's sharing of the Nobel Prize for physiology in 1981. By now,the literature on CHS is immense.

The other conclusion was the demonstration of relative hemispheric independence ("duality of mind") which had already been well established in cats and monkeys by Sperry and his students including R. Meyers, C.Hamilton, M. Gazzaniga and C.Trevarthen. This second main conclusion has had relatively less discussion although it seems to me to be at least as important( see Bogen refs. OSOB II 1969, Dual Brain 1985, Mental Duality 1986, and One's Other Mind 2000).

The former conclusion (CHS) has by now ,2001, become widely accepted. The second conclusion was debated for a time by philosophers but the question has for nearly two decades been largely ignored by them as well as a majority of neuroscientists. Some comment on this by me can be found on this website as the addendum to the book review listed in the table of contents for consciousness.