Differences Between the Left and Right Brain

Left, right, left, right--the marching song of the two-mind movement. To hear them talk, you'd think that everyone had a second mind, suppressed by the first. That the vocal left brain dominated the poor artistic right brain. Preventing it from getting a creative thought in edgewise. Soon there will be a consciousness raising movement: Stop referring to the left cerebral hemisphere as the "dominant" one. Invent a more egalitarian term like co-chairperson. Co-chairhemisphere?

Alas. Were cerebral physiology so simple! If there were strong dominating influences, it would make our research far easier. It is unfortunate that "dominance" is a word with two entirely different meanings, even within psychology. When talking about pecking order, dominant refers to an animal that usually wins in a one-on-one encounter, the animal that can approach, threaten, and successfully displace another animal from food, mates, or the best nesting place. In talking about the cerebral hemispheres, however, dominant is merely a shortening of the technical term "language-dominant hemisphere." It is the outcome of a test to find out where language lives in a person's brain, such as injecting anesthetics into the left and right carotid arteries and seeing when the patient stops talking (or the simpler, but not as accurate, test that merely involves having the subject look at a dot in the middle of a screen and then briefly flashing words to the left or right of the fixation point; people with left-brain language will have an easier time with right-sided words since the information goes first to left brain).

Although a few percent of people have right brains that are language-dominant, about 93 percent of us use the left side. A few percent have "mixed dominance," where both sides are used for language (that is, injecting anesthetics on either side will interfere with speech). But the term hardly refers to language dominating art or music: it's just which side is more essential for language than the other.

Shades of gray become black and white when the dichotomizers go into action. But the real problem is that most of the creativity arguments have about as much to do with the brain as does the English language. The structure of the brain probably has a lot to do with the capability for, even the "deep structure" of, language--but brains hardly come in Chinese, Swahili, and English flavors. Like English per se, the creativity and holistic thinking influences probably lie more in the realm of culture than brain structure. And hardly on a particular side of the brain.

A few decades ago, similar suppressed-creativity arguments were floating around. It's just that they were then phrased in terms of contemplative Eastern thought versus authoritarian Western religious influences. More recently, the dichotomous rendition was holistic versus linear thinking. And now the mod metaphor is right brain versus left brain. Except that it is the worst of mixed metaphors, the kind that mixes up metaphor with reality.

Being a neurophysiologist, I suppose I ought to feel that progress has been made: in no other age could it have taken a mere twenty years to shift from a predominantly religious metaphor to a semi-scientific one. But the neurophysiologists and neuropsychologists who specialize in the human cerebral cortex are starting to view the left-righters with something of the wariness which the astronomers reserve for astrology.

In one sense, the picture of the mind painted by the left-righters is rather like one of those magazine illustrations of the human brain and its convoluted surface--one feels quite sure that the artist has never seen a real human brain, either a fresh one or a preserved one. The result of embroidering upon another artist's rendition bears even less fidelity to the original, an artistic version of the spread of a rumor. My favorite painting of the brain's convoluted surface is not