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Sep 12, 2010

Of all the problems I worry about digital books, them being too clear and easy to read is not the most pressing issue for me. But I still found this interesting.

Stanislas Dehaene, a neuroscientist at the College de France in Paris, has helped illuminate the neural anatomy of reading. It turns out that the literate brain contains two distinct pathways for making sense of words, which are activated in different contexts. One pathway is known as the ventral route, and it’s direct and efficient, accounting for the vast majority of our reading. The process goes like this: We see a group of letters, convert those letters into a word, and then directly grasp the word’s semantic meaning. According to Dehaene, this ventral pathway is turned on by “routinized, familiar passages” of prose, and relies on a bit of cortex known as visual word form area (VWFA). When you are a reading a straightforward sentence, or a paragraph full of tropes and cliches, you’re almost certainly relying on this ventral neural highway. As a result, the act of reading seems effortless and easy. We don’t have to think about the words on the page.

But the ventral route is not the only way to read. The second reading pathway – it’s known as the dorsal stream – is turned on whenever we’re forced to pay conscious attention to a sentence, perhaps because of an obscure word, or an awkward subclause, or bad handwriting. (In his experiments, Dehaene activates this pathway in a variety of ways, such as rotating the letters or filling the prose with errant punctuation.) Although scientists had previously assumed that the dorsal route ceased to be active once we became literate, Deheane’s research demonstrates that even fluent adults are still forced to occasionally make sense of texts. We’re suddenly conscious of the words on the page; the automatic act has lost its automaticity.

This suggests that the act of reading observes a gradient of awareness. Familiar sentences printed in Helvetica and rendered on lucid e-ink screens are read quickly and effortlessly. Meanwhile, unusual sentences with complex clauses and smudged ink tend to require more conscious effort, which leads to more activation in the dorsal pathway. All the extra work – the slight cognitive frisson of having to decipher the words – wakes us up.

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