Things I read today (neuroscience of literacy – you’ve begun to read)

December 6th, 2009 by amy

Right now, your mind is performing an astonishing feat. Photons are bouncing off these black squiggles and lines — the letters in this sentence — and colliding with a thin wall of flesh at the back of your eyeball. The photons contain just enough energy to activate sensory neurons, each of which is responsible for a particular plot of visual space on the page. The end result is that, as you stare at the letters, they become more than mere marks on a page. You’ve begun to read…

But reading isn’t just about seeing — we still have to imbue those syllabic sounds with meaning. This is why, once the letterbox area deciphers the word — this takes less than 150 milliseconds — the information is immediately sent to other brain areas, which help us interpret the semantic content. Such a complex act requires a variety of brain areas scattered across both hemispheres, all of which must work together to make sense of a sentence…

…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.”…

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.

Reading in the Brain By STANISLAS DEHAENE, Reviewed by Jonah Lehrer

a single neuron, fascinating

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