Tuesday, February 10, 2009

Why We Ask "Why"?

That we have brains whose left and right hemispheres specialize isn't unheard of in the animal kingdom, but it's odd. Not just because animals tend to be symmetrical, and even choose mates based on how symmetrical (apparently free from genetic mutations) they appear, but because backup systems aid in survival. Our hemispheres are complementary, more like fraternal twins than like clones. Why would some abilities be laid down in only one hemisphere?

For decades, Michael S. Gazzaniga, director of Dartmouth's Centre for Cognitive Neuroscience, has been conducting ingenious experiments with "split brain" people, whose corpus callosum has been surgically severed to prevent the spread of epilectic seizures. Such studies offer insight into how the hemispheres divide their labor. For example, if a split-brain person looks at something only with the right eye (which corresponds to the left hemisphere of the brain), he can say what he sees. But show the same picture to his left eye (right hemisphere) and he'll "see" nothing. The Cheshire cat effect it's called, after the peek-a-boo cat in Lewis Carroll's Alice's Adventures in Wonderland. When the right brain is asked to point to the "invisible" object, the person has no trouble. Many clever experiments with long-suffering volunteers have revealed the left brain to be talkative, the right silent.

In another of Gazzaniga's experiments, a personal favorite of mine, he showed one large picture and four small pictures to each of a volunteer's hemispheres, and then the volunteer was asked to choose the small picture that seemed related to the large one. Neither side knew what the other side was viewing. For a snowstorm scene, the volunteer's right brain had to choose among a shovel, a lawn mower, a rake, and an ax. To go with a picture of a bird's foot, his left brain had to choose among a toaster, a chicken, an apple, and a hammer. Not surprisingly, the right brain correctly chose the shovel for the snowstorm, and the left brain correctly chose the chicken for the bird's foot.

Then things got really interesting. When Gazzaniga asked the subject why his right hemisphere had chosen the shovel, his talky left hemisphere answered, but since the split hemispheres couldn't exchange information, it didn't know about the snow scene and had no idea why the shovel was chosen. So it quickly made up a plausible explanation based on the only information it had, that a chicken was somehow involved. The subject reasoned: "The chicken claw goes with the chicken and you need a shovel to clean out the chicken shed." Good answer, if wrong. Gazzaniga calls the left brain the Interpreter, "a device that seeks explanations for events and emotional experiences." When something bad or advantageous happens, it's essential to know why so one can predict and prepare for future events. Mystery causes a mental itch, which the brain tries to soothe with the balm of reasonable talk. The left brain, that is; the right brain prefers to turn a mute eye.

Born fictioneers, all of us, we quest for causes and explanations, and if they don't come readily to hand, we make them up, because a wrong answer is better than no answer. Also, a fast good-enough answer is better than a slow perfect answer. We're devotees of the hunch, estimate, and best guess. I find it hard to watch, say, a David Lynch film like Mulholland Drive, which shards into free-associative imagery halfway through, and not try to figure it out. Critics plaque Lynch with "But what does it mean?" It's not enough to be startling, beautiful, artful, it has to mean, even if much of life simply is. Despite knowing that, my left hemisphere, not content to joyously perceive, insists on asking why. A word children use relentlessly and adults continue asking. And so we pass our lives, striving to make sense, even if it produces nonsense, which, of course, we never utter, only other people with less-exacting minds. Otherwise, we'd feel at sea, and painfully sure, as the philosopher William Gass says in an essay, that "life, though full of purposes, had none, and though everything in life was a sign, life managed, itself, to be meaningless."

... An Alchemy Of Mind, Diane Ackerman

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