READING IN THE BRAIN

A neuroscientist explains how the brain deals with reading.

Dehaene (Experimental Cognitive Psychology/Collège de France; The Cognitive Neuroscience of Consciousness, 2002, etc.) begins by pointing out that the brain contains circuitry exquisitely attuned to reading. Humans began to read only 5,000 years ago, so eons of evolution could not have designed it. Since genes haven’t evolved to enable us to read, writing systems have adapted to constraints in the human brain. The author describes experiments using dazzling, high-tech devices that image the brain while a subject reads. The retina sends everything we see to the extensive visual areas at the rear of the brain. An instant later, any written word, in any language, lights up a tiny area. Closer examination of this “letterbox area” reveals a smaller section sensitive only to simple lines and curves, an adjacent area that forms these into letters and another that recognizes words. This is the identical area and mechanism which animals use to recognize objects in their environment, so evolution has cleverly recycled existing brain circuits to handle reading. Dehaene stresses that these findings should help teach reading—phonics trump the whole word method, which has no basis in brain physiology—and treat dyslexia, which is rare in “transparent” languages (i.e., where one letter equals one sound) like Italian but epidemic in English where irregular spelling makes it much harder for the brain to decode words.

Dense with ideas and experiments, but richly rewarding for readers willing to put in the effort.