csc@watmath.UUCP (Computer Sci Club) (08/21/85)
Ms. Sunny Kirsten writes: > The human brain is composed of two hemispheres. Some people believe >(others, I think the minority, object), that the logical and mathematical and >the spatial perceptive abilities are active primarily in the left hemisphere, >and that these are more adept in males than females, and, conversely, that, >the emotional and intuitive and artistic abilities are active primarily in >the right hemisphere, and that these are more adept in females than males. The statements here are much more controversial than the above passage implies. While it is true that a large body of evidence has accumulated over recent years showing some differentiation of function between the two hemispheres, the theory that "emotional and intuitive and artistic abilities are active primarily in the right hemisphere" is an artifact of highly speculative popularizations of the basic research. The theory is certainly not supported by the present body of scientific evidence. As Howard Gardner puts it in his article "What we know (and don't know) about the two halves of the human brain": It is becoming a familiar sight. Staring directly at the reader -- frequently from a magazine cover -- is an artist's rendition of the two halves of the brain. Surprinted athwart the left cerebral hemisphere (probably in stark blacks and grays) are such words as "logical", "analytical", and "Western rationality". More luridly etched across the right hemisphere (in rich orange or royal purple) are "intuitive", "artistic", or "Eastern consciousness". Regrettably, the picture says more about a current popular science vogue than it does about the brain. ([1] p. 24) In a scathing (and often hilarious) essay on this controversy, "Left brain, Right brain: Science or the New Phrenology?", William Calvin writes: "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" ([2] p 104). Even Springer and Deutsch who are quite sympathetic to these types of speculations call the chapter of their book "Left Brain, Right Brain" [3] which deals with these speculations "Beyond the Data: Speculative Issues". Calvin sums up the problem nicely: If you try tracing some of the left-righters' enthusiasms back to the scientific evidence, you'll often wonder how the rumor ever got started. It is not that the scientific evidence contradicts their notions, though that sometimes happens. But they've gotten way out in front of the state of the scientific art, in about the same way as the phrenologists' maps (all those political subdivisions on the brain map marked love, acquisitiveness, compassion, etc.) were premature, quite unsupported by any evidence at the time. ([2] p.104) There do exist differences between the hemispheres (an overview can be found in [1], while [3] is quite detailed) dealing with, among other things, language processing and spatial recognition. But these differences are by no means as pronounced nor as uniform as might be inferred from a reading of the popular press. There is also evidence suggesting that there is an inherent difference in the way in which male and female brains specialize, but this difference is NOT, "male brains are more adept at left hemisphere functions, female brains are more adept at right hemisphere functions". (see for instance [3] pp. 121-130) Again the differences are by no means completely uniform. Note that this article confines itself to a discussion of the left brain/ right brain section of Ms. Kirsten's article. I offer no opinion at this time as to the basic validity of the argument that observed behavioral differences between the sexes can be traced to physiological causes. I do argue that the theory that these physiological causes include a sex difference in the degree to which the right and left hemispheres are used is completely unsupported by the current evidence. William Hughes [1] Gardner, Howard, "What we know (and don't know) about the two halves of the brain", Harvard Magazine, v.80 no.4 (mar-apr 78), pp. 24-27 [2] Calvin, William, "The Throwing Madonna" chapter 10 "Left Brain, Right Brain: Science or the New Phrenology?", McGraw-Hill, New York, 1983 [3] Springer S. and Deutsch G., "Left Brain, Right Brain", W. H. Freeman and Company, San Francisco, 1981