Though the brain's left hemisphere is commonly believed to be the "seat of language," the right hemisphere processes a number of subtle linguistic functions. This paper will argue that the degree of right-hemispheric involvement in language is what differentiates "poetic" or "literary" from "referential" or "technical" speech. It will suggest that the absence of left- hemispheric dominance for language in the brains of preliterate and illiterate persons may explain why those populations exhibit so-called "magical" thinking rich in right-hemispheric features. Finally, it will link studies demonstrating high rates of mania and hypomania among poets (but not other types of writers or creative artists) to other studies observing a temporary shift from left- to right-hemispheric dominance for language during the manic phase, suggesting that overactivation of these brain regions may underlie the compulsion to write poetry.
keywords: poetry, poets, right hemisphere, brain, language, mania, hypomania, affective disorders, laterality, literacy
[We are sometimes told] to 'look into our hearts and write.' But that is not looking deep enough. . . . One must look into the cerebral cortex, the nervous system, and the digestive tracts.
-T. S. Eliot
Originally published in Journal of Consciousness Studies, 11, No. 5-6, 2004, pp. 21-59. Reproduced with permission
The human brain is divided into two hemispheres, right and left, that are joined by a thick 'cable' of neural fibres called the corpus callosum. It has long been observed that injury to the left hemisphere in the average adult damages speech, speech comprehension, and reading, and causes paralysis on the right side of the body. Injury to the right hemisphere, on the other hand, seems to leave linguistic capabilities intact, but causes paralysis on the left side of the body. These observations have given rise to the twin concepts of contralaterality of hemispheric control (i.e., that each hemisphere controls the opposite side of the body) and cognitive specialization of hemispheric function. As far back as the nineteenth century, it was recognized that the left hemisphere's specialty was language. Pioneering British neurologist John Hughlings Jackson asserted in 1868 that the left hemisphere was the 'leading side' in most people, responsible for the control of speech and will. In the decade of the 1940s, French neurologist Henry Hécaen and British psychologist Oliver Zangwill demonstrated that the right hemisphere, far from being passive, controlled visuospatial processing (Benton, 1991). Particularly in the decade of the 1970s, mass market publications popularized the notion of the left brain as the processor of language and rational thought and the right brain as the processor of visuospatial images and holistic or intuitive awareness. Hippies and artists were believed to be 'right brain' in orientation, while engineers and businessmen were believed to be 'left'. Indeed, the rather overly enthusiastic adoption of early laterality findings by western popular culture (exemplified by brain dominance quizzes on newspaper feature pages and the advertising of Saab automobiles as 'a car for both sides of your brain') made the whole subject seem rather oversimplified and absurd, and no doubt helped to blind the general public to an awareness of the implications of later research findings in the field of cerebral laterality.
Today it is known that, in about 97 per cent of all right-handed adults, the left hemisphere is dominant for language (Pinker, 1994). Even among the lefthanded population, the great majority, 69 per cent, process language in their left hemispheres, like right-handers (Pinker, 1994). Moreover, the sharply increased rates of neurological deficits such as mental retardation, autism, stuttering, dyslexia, and epilepsy among left-handed individuals (Iaccino, 1993) would make it seem even more apparent that left-hemispheric language is the 'norm' and right-hemispheric language a deviation from that norm. …