By Adam Leonard
Michael S. Gazzaniga is a pioneering neuroscientist in split-brain research who is currently Director of the SAGE Center for the Study of the Mind at the University of California, Santa Barbara. His books for non-scientists, from /The Social Brain/ (1985) to /The Ethical Brain/ (2006), have allowed anyone with an interest to follow the fascinating and revealing research being conducted with patients whose brain hemispheres had to be “split” (the connecting corpus callosum severed) to control life-threatening epilepsy.
The most intriguing – and potentially momentous – discovery arising from this research is not the much publicized left-brain, right-brain differences, but the uncovering of a function in the speaking hemisphere (usually the left-brain) that may prove instrumental to understanding Man’s recurring irrational behavior. The function, called the “interpreter,” apparently generates conscious and implicitly believed “rational” explanations for anything we do or feel in response to unconscious motivations.
Gazzaniga’s books describe how it is possible to provide information selectively to only the left (speaking) brain or the right (non-speaking) brain of a split-brain patient and monitor their responses. The startling discovery was that whenever the non-speaking brain was given a command to perform some action and the patient obeyed it, the speaking brain (which knew nothing of the command) would generate an explanation to explain the action … and would believe the explanation truly /was/ the reason for the action.
For example: the non-speaking brain could be instructed, “walk,” and the patient would stand up and begin walking away; if asked why, he (his speaking brain) would reply that he was going to get a drink, or a coke, or whatever. /Never/ would the speaking brain be nonplused or seem surprised by whatever action the non-speaking brain initiated, but would calmly explain it away with varying degrees of logic. … If the explanation seemed implausible and the patient was questioned about it, he would become annoyed, even angry, for he clearly believed it to be the true reason he’d performed the action.
The existence of the interpreter function has been known for over twenty years, and has been incorporated into Psychology’s explanations of self-deception, self-serving biases, cognitive dissonance, and defense mechanisms of the ego. What scientists have not yet addressed, however, is the possibility that the interpreter function explains how Man can be a tribal territorial animal (with DNA 98% the same as chimpanzees!) but totally unaware of any animal instincts affecting his behavior. … Is it possible that our chronic irrational behavior may actually be driven by instincts, but the interpreter covers this up by generating rational explanations for our irrational behavior, and convincing us the explanations are true? … Is it possible that the reason Man has never been able to live in peace is simply that as tribal territorial animals we compulsively form tribes and war with one another? … Is it possible that is also why we compulsively take sides and argue issues – such as this one – angrily and irrationally, as if they were territory to be taken or defended?