How the mind reads

416NQwBS-+L._SY344_BO1,204,203,200_Years ago I walked down the main street of a town I had lived in for years, and noticed some new apartments above the retail shops. When I got back home I told my girlfriend about my discovery, and she rolled her eyes and explained patiently that they’d always been there. The fact is that I’m notorious for not noticing things. I have no attention to visual detail. I’m a tunnel-vision sort of person.

In Stanislas Dehaene’s Reading in the Brain he outlines a neuronal recycling hypothesis, which might explain my strange behavior. The gist is that there are regions of the brain which have been co-opted for reading. In particular, the letterbox region of the brain. It turns out that processing text is localized to a small zone of the left hemisphere, and damage to this area can have consequences for reading comprehension. In many ways the symptoms are similar to aphasia, but a tight analogy would be somewhat perplexing.* Language is a core human competency. Though it needs cultural and social input, it seems clear we have a built in facility toward it. Or at least that is the consensus among cognitive scientists. It has almost certainly been the target of natural selection.

The same can not be said for literacy, which is only 5,000 years old, and, whose widespread penetration among humans is only a feature of the last few hundred years. ~25 percent of the world’s population is still illiterate. In contrast, those who can not speak are considered to have some sort of pathology. How then can there be a region of the brain dedicated to text comprehension? Reading seems to leverage pattern recognition capabilities which have deep evolutionary roots, and those recognition capabilities are localized to particular regions of the brain. This localization occurs early in life, but is not hardwired, so very early damage can result in rerouting to other regions (also, slight differences cross-culturally in positioning can be explained as a function of the nature of letters and length of words).

Dehaene reports that this fact imposes constraints on the nature of symbols utilized in text. For example, letters exhibit a distribution of common to rare patterns which are similar to a sort of stimuli we would experience in nature. That is, particular letter forms are over-represented in all world writing form representations, and those forms correspond to the sort of patterns one sees in the natural environment. The similarities of distributions are curious especially in light of the fact that writing systems evolve over time to become more abstract and less concrete from more elaborate, often pictographic, forms. Convergence in phenomenon rooted in our cognitive architecture implies that there are genuine constraints and biases in the shape of our cultural expression.

51IgD1yKTiL._SY344_BO1,204,203,200_Many of the reviewers of Reading in the Brain highlight that it is interminably technical across its many chapters. The author admits as much as he nears his conclusion and attempts an apologia for testing the reader’s patience. Certainly the repetitive survey of neuroanatomy, or the deep-dive into the cognitive neuroscience of symmetry, seemed a bit much for me as someone without a neuroscience background. But when he comes up for air it turns out that Dehaene’s ultimate goal is very ambitious: to explain the variation of culture as a function of cognitive neuroscience. To do this he refers to the large body of work produced by Dan Sperber, a cognitive anthropologist who argues that culture is an “epidemiology of representations.” It is basically an elaborated model of viral memes, where the cognitive landscape of our minds canalize cultural expression toward particular aesthetically appealing or functionally effective forms. For Dehaene reading, literacy, is a form of viral culture. It gives us pleasure (novels), and, it is functionally useful (accounting). Developed over the last several thousand years independently at least twice, and likely more than twice, it seems to be at an intersection of our facility for language, memory, and symbolic representation, which is naturally evoked out of the environment of complex societies. If we could create mentats we would. Their non-existence is a testament to the difficulties of such an enterprise. As it is, we’ll have to make do with reading, and the symbolic manipulation which reading allows. Culture then, is a finite set of phenomena which express novel syntheses of our cognitive capacities. Dehaene in particular emphasizes the role of the domain-general neocortex in threading together disparate domain-specific functions into cultural novelties (e.g., the visual recognition and language competencies necessary for reading).

51QrNyN0KzL._SY344_BO1,204,203,200_Nestled between the abstruse cognitive neuroscience and speculative theorizing about the nature of culture Dehaene has some concrete suggestions on policy. Whole language learning is a travesty, and phonics are the way to go if you want to encourage early literacy. He seems frustrated that some teachers consider phonics “right-wing” and so favor whole language learning. The science says that whole language learning is by and large bunk, even if there are some techniques which are salvageable. Whole language learning shaves years off reading abilities according to Dehaene. Apparently it can take until adulthood for whole language learners to catch up with those who utilized phonics. In an area where policy is probably impotent, English speakers are at a major disadvantage to Italian or Finnish speakers because of irregular spelling (French is between the two groups). Absorption of complex literature is retarded among British and American students because more time in elementary school must be spent mastering the profusion of words (obviously Chinese readers have a similar issue with delayed reading of higher literature due to the cognitive overhead of written Chinese). Finally, though therapy and treatment can mitigate dyslexia, Reading in the Brain left me very happy that my daughter (who is now reading) does not exhibit this problem. It seems a major handicap.

Which brings me back to my anecdote about my personal ability to not “notice” things. I’ve been a big reader my whole life (you can see which books I remember reading at Good Reads). So I was naturally curious about the cognitive neuroscience of this phenomenon. One of the implications of Dehaene’s neuronal recycling hypothesis is that there is an opportunity cost to devoting one’s resources to reading comprehension. The area of the brain which becomes the letterbox region may very well be the area devoted to noticing subtle differences in one’s environment that make trackers among indigenous people seem preternatural in their aptitudes. The way some stems of leaves have become askew, for example, may be the root of many of the letters which we use to represent sounds. Perhaps then my lack of ability to “notice” small things in the world around me is inextricably linked to the fact that my life’s focus has been on text, more or less. It’s a trade-off that I’m happy with.

* Also, damage to the letterbox region can impair recognition of letters, while allowing for number recognition!

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