Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The Social Brain
The US neurophysiologist Michael Gazzaniga, a disciple of Roger Sperry (the psychologist commonly associated with the discovery of the "split brain") showed that the brain has a modular organization, whereby many independent systems work in parallel.
These "specialized" modules are evolutionary additions to the brain: it is no surprise that they perform different functions, and it is not surprising that those functions are useful to the overall functioning of the brain.
Split-brain surgery had already proved that the human brain is made of at least two brains (the two hemispheres). Gazzaniga simply extended that idea.
Basically, he thinks that many minds coexist in a confederation. Our behavior is due to the activity of these modules, rather than to conscious decisions.
A special module, the "interpreter", located in the left hemisphere, interprets the actions of modules and provides explanations for our behavior. However, that happens after the unconscious modules have already determined our behavior. Beliefs do not precede behavior: they follow it. They are created by the interaction of the interpreter with the other modules. Behavior determines our beliefs, not the other way around. It is only by behaving that we conceptualize our selves, that we build a theory of our psychological state (in particular, beliefs).
Ultimately, mental life (the life of the interpreter) is the reconstruction of the independent operations of many brain systems.
There are many "i”'s and then one "i" that makes sense of what all other "i"'s are doing.
Initially, Gazzaniga took issue with the view of the "specialized" hemispheres. It is not true that the two hemispheres are highly specialized units, and that language is "localized" in the left hemisphere: the only thing that is "lateralized" is language, and language uses up space within an hemisphere at the expense of non-linguistic features of that hemisphere. Lateralization (the fact that each hemisphere is endowed with capabilities that the other hemisphere lacks) is not specialization.
Gazzaniga and his associates also discovered 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 communicate with each other.
The only way for the brain to realize its whole knowledge is for it to watch itself as it behaves. Therefore, behavior must be the source of communication between modules. 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.
Then Gazzaniga reached another important conclusion: the conscious self is not aware of our actions before we perform them but only afterwards, although it “thinks” that it caused the action. Inspired by the 1956 theory of "cognitive dissonance" by the US psychologist Leon Festinger, Gazzaniga 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. In a sense, we become aware of our actions only "after the fact", as already discovered in 1965 by the US physiologist Benjamin Libet ("Cortical Activation in Conscious and Unconscious Experience", 1965), based on the experiments on the "Bereitschaftspotential" or readiness potential carried out in 1964 in Germany by Hans-Helmut Kornhuber and his student Lueder Deecke.
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, grows 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 reality there exists a conglomerate of selves.
There is still a puzzle, though, in Gazzaniga’s theory: if different brain regions are perfectly capable of providing good reactions to the various situations we encounter, why is there any need for consciousness at all to make sense of the world? Why is there a need for an "interpreter"? (And one that, according to Gazzaniga's findings, makes all sorts of mistakes). If consciousness has no effect on the working of these brain regions, then it's difficult to imagine why it would appear over the course of evolution. If it does have an effect, then Gazzaniga cannot claim that it is merely an "interpreter"...
Note: The US neuroscientist Aaron Schurger provided an alternative explanation of Libet's experiment which would make Gazzaniga's theory false ("An accumulator model for spontaneous neural activity prior to self-initiated movement", 2012).
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