Stanislas Dehaene, a distinguished French cognitive scientist, who wrote Reading in the Brain is reviewed by the NYT's Sunday Book Review.
In one of the most interesting chapters, he argues that the shapes we use to make written letters mirror the shapes that primates use to recognize objects. After all, I could use any arbitrary squiggle to encode the sound at the start of “Tree” instead of a T. But actually the shapes of written symbols are strikingly similar across many languages.
It turns out that T shapes are important to monkeys, too. When a monkey sees a T shape in the world, it is very likely to indicate the edge of an object — something the monkey can grab and maybe even eat. A particular area of its brain pays special attention to those significant shapes. Human brains use the same area to process letters. Dehaene makes a compelling case that these brain areas have been “recycled” for reading. “We did not invent most of our letter shapes,” he writes. “They lay dormant in our brains for millions of years, and were merely rediscovered when our species invented writing and the alphabet.
However, the very fact that our brains have become so exquisitely adapted for reading looks like an argument against the second kind of innateness — the written in stone kind. Dehaene also endorses the Chomskyan view that reading is highly constrained — that “new cultural inventions can only be acquired insofar as they fit the constraints of our brain architecture” — but it’s not so clear that he really believes it himself. For example, he argues that the primate brain has evolved to treat symmetrical shapes, like the letter pairs p and q, or b and d, as if they were the same. This explains why children, and dyslexics, have so much trouble distinguishing these letters. It also explains our extraordinary ability to “mirror-read” and “mirror-write.” Many children spontaneously reverse not just single letters but whole paragraphs of text.