Book review of Michael Gazzaniga

Michael Gazzaniga & Joseph LeDoux
INTEGRATED MIND (Plenum Press, 1978)

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Based on the studies of split brain patients, the authors present a theory that what is transferred between the emispheres is neural codes to maintain an informational balance and provide for mental unity.
But, mainly, the authors criticize the view that the two emispheres are highly specialized units, and that language is "localized" in the left hemisphere, and reduce lateralization to the lateralization of linguistic skills. It is not that each hemisphere has a different cognitive "style": the only thing that is lateralized is language, and language uses up space within an hemisphere to the expense of nonlanguage features of that hemisphere. Lateralization (the fact that each hemisphere is endowed with capabilities that the other hemisphere lacks) is not specialization.
Psychological experiments have shown that an experience has multiple aspects which are stored at different places in the brain. These memory locations are coherent but do not seem to comunicate with each other. The only way for the brain to realize its whole knowldge is for it to watch itself as it behaves. Therefore, behavior is the source of communciation. Once a memory system causes behavior, the other memory systems become "aware" of those impulses/knowledge coming from the memory system that caused the behavior to occur.
By examining his patients, Gazzaniga reached another important conclusion: the conscious self is not aware of our actions before we perfomr them but only afterwards, although it often attributes cause to the action. Inspired by the theory of "cognitive dissonance" of the American psychologist Leon Festinger, Gazzinga concludes that one of the selves, the verbal self, keeps track of what the person is doing and from that interprets reality. As Festinger originally put it, the sense of reality arises as a consequence of considering what one does.
Gazzaniga postulates the existence of multiple mental systems in the brain, each with the capacity to produce behavior. During growth one mental system, the verbal one, comes to "oversee" the others. The mind is not a psychological entity but a sociological entity. Language allows us to create a personal sense of conscious reality out of multiple mental realities. The job of the verbal system is to make sense of mental activity and therefore provide the illusion of the self, when in actuality there exists a conglomerate of selves.

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