And there's more on the functions of the two halves of the brain. Even healthy brains are constantly constructing a false narrative that allows us to function in the world.
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In the previous chapter, we met the plight of split-brain patients, who sometimes struggle with alien hands that literally have a mind of their own. It does appear that there are two centers of consciousness living within the same brain. So how does all this create the sense that we have a unified, cohesive “self” existing within our brains?
I asked one person who may have the answer: Dr. Michael Gazzaniga, who has spent several decades studying the strange behavior of split-brain patients. He noticed that the left brain of split-brain patients, when confronted with the fact that there seem to be two separate centers of consciousness residing in the same skull, would simply make up strange explanations, no matter how silly. He told me that, when presented with an obvious paradox, the left brain will “confabulate” an answer to explain inconvenient facts. Dr. Gazzaniga believes that this gives us the false sense that we are unified and whole. He calls the left brain the “interpreter,” which is constantly thinking up ideas to paper over inconsistencies and gaps in our consciousness.
For example, in one experiment, he flashed the word “red” to just the left brain of a patient, and the word “banana” to just the right brain. (Notice that the dominant left brain therefore does not know about the banana.) Then the subject was asked to pick up a pen with his left hand (which is governed by the right brain) and draw a picture. Naturally he drew a picture of a banana. Remember that the right brain could do this, because it had seen the banana, but the left brain had no clue that the banana had been flashed to the right brain.
Then he was asked why he had drawn the banana. Because only the left brain controls speech, and because the left brain did not know anything about a banana, the patient should have said, “I don’t know.” Instead he said, “It is easiest to draw with this hand because this hand can pull down easier.” Dr. Gazzaniga noted that the left brain was trying to find some excuse for this inconvenient fact, even though the patient was clueless about why his right hand drew the banana.
Dr. Gazzaniga concludes, “It is the left hemisphere that engages in the human tendency to find order in chaos, that tries to fit everything into a story and put it into a context. It seems that it is driven to hypothesize about the structure of the world even in the face of evidence that no pattern exists.”
This is where our sense of a unified “self” comes from. Although consciousness is a patchwork of competing and often contradictory tendencies, the left brain ignores inconsistencies and papers over obvious gaps in order to give us a smooth sense of a single “I.” In other words, the left brain is constantly making excuses, some of them harebrained and preposterous, to make sense of the world. It is constantly asking “Why?” and dreaming up excuses even if the question has no answer.
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The aforementioned "gaps in our consciousness" was an interesting tidbit also. We perceive consciousness as one long but generally uninterrupted segment that fills the gaps between wakefulness and sleep, but the picture that emerges from science is something different altogether.