Book review from The Frontal Cortex on Dehaene's new book, looks very cool: http://scienceblogs.com/cortex/2009/11/ … rain_1.php
Frontal Cortex wrote:
"Dehaene begins by introducing the reader to the "letterbox area," a small bit of brain just behind the left ear. The crucial role of this cortical part was first revealed by Mr. C, a 19th-century neurological patient who, after a mild stroke, lost the ability to read. What made Mr. C's case so peculiar is that his vision was perfectly fine; he could make sense of objects and faces and even numbers. However, when he opened up a book or glanced at a newspaper, the letters on the page were utterly inscrutable, a mess of inchoate lines and curves. "He [Mr.C] thinks that he has lost his mind," his doctor dryly noted.
Subsequent studies of patients with pure alexia -- they can see everything but written language -- have located the specific contours of the letterbox area. Not surprisingly, it takes up a significant chunk of our visual cortex, as the invention of the alphabet seems to have usurped brain cells previously devoted to object recognition. (Dehaene refers to this process as "neuronal recycling.") He also speculates that, while "learning to read induces massive cognitive gains," it also comes with a hidden mental cost: because so much of our visual cortex is now devoted to literacy, we're less able to "read" the details of natural world...
... The second major mystery explored by Dehaene is how reading came to exist. It's a mystery that's only deepened by the recency of literacy: the first alphabets were invented less than 4,000 years ago, appearing near the Sinai Peninsula. (Egyptian hieroglyphic characters were used to represent a Semitic language.) This means that our brain wasn't "designed" for reading; we haven't had time to evolve a purpose-built set of circuits for letters and words. As Deheane eloquently notes, "Our cortex did not specifically evolve for writing. Rather, writing evolved to fit the cortex."
Deheane goes on to provide a wealth of evidence showing this cultural evolution in action, as written language tweaked itself until it became ubiquitous. In fact, even the shape of letters -- their odd graphic design -- has been molded by the habits and constraints of our perceptual system. For instance, the neuroscientists Marc Changizi and Shinsuke Shimojo have demonstrated that the vast majority of characters in 115 different writing systems are composed of three distinct strokes, which likely reflect the sensory limitations of cells in the retina. (As Dehaene observes, "The world over, characters appear to have evolved an almost optimal combination that can easily be grasped by a single neuron.") The moral is that our cultural forms reflect the biological form of the brain; the details of language are largely a biological accident."
Dehaene's written some interesting work with others, centered around rigorous studies, and usually I see it spun both ways, but the research itself is fascinating, regardless of how you skew its implications.
Last edited by nest0r (2009 November 24, 3:01 am)
