A review of Dehaene (2009) Reading in the Brain

A review of Stanislas Dehaene (2009) Reading in the Brain: the science and evolution of a human invention, Penguin, New York.coverreadinginthebrain

When I first came across this book it was only available in America so I read it in electronic form via my Sony e-reader.  Now I am getting used to this format I find I can read quite rapidly and it is motivating skipping through the electronic pages at quite a pace.  The e-reader  also has the function of being able to flip back and forth to the footnote references as the touch of a stylus.  I could also highlight text that was worth quoting from and create a bank of notes of my own.  The other thing was that, when Dehaene was talking about reading fluency and the way our brain deals with different arrays of print, I could experiment with different sizes and column widths to see what this felt like.  I certainly have an optimal print size for rapid reading. Neither the hard copy nor the e-book has colour illustrations of some detailed and fascinating brain imagery and diagrams Dehaene uses.  However, there is a web site where all these can be viewed: .http://pagesperso-orange.fr/readinginthebrain/figures.htm

The aim of this book is to explain some of the brain circuitry behind reading.  Given that writing (and so reading) is a cultural invention, developing some 5000 to 8000 years ago, the human brain, whose evolutionary development was much older, could not have had a pre-existing reading function.   Dehaene suggests as an explanation for this anomaly a form of “neuronal recycling”, whereby existing networks of connections (for shape recognition and making sense of the visual world) are “co-opted to the task of recognising the printed word” (p. 8).  Reading (for people to whom it comes easily) is such a streamlined process that Dehaene also surmises that indeed the cultural development of writing was influenced by what fitted best to this “cortical niche” (p.121).That is to say, writing is like it is because of our brains as much as vice versa.  Dehaene’s research has shown that people reading such diverse languages as English, French, Japanese and Mandarin Chinese use much the same brain circuitry.

The key area in the brain that starts by recognising letter shapes and words is in the left occipital-temporal region.  Dehaene coins the term “the brain’s letter box” (p.53) for this area.  Clusters of neurons in this area have become specialised to visual recognition of different types of images, with a particular “sweet spot” (p.136) for letter string recognition.  Dehaene’s reasoning is then that the brain processes rapidly and in parallel different aspects of the written text, letters, graphemes, syllables, sounds and meanings in both a top down and bottom up series of checks with different aspects of our language lexicons.  The reading process is complex but also highly developed and efficient, allowing most children to pick up the facets of reading in a couple of years.  The brain’s plasticity allows it to develop new circuitry as we learn.  The competent adult reader then has a fully integrated visual, phonological and lexical system for reading that allows us to make sense of text via a series of mostly unconscious and automatic operations.  Like many academic researchers whose evidence is predominantly from the laboratory Dehaene is strongest and most detailed on his theorising about single word reading.  He has less to say about the more complex issues involved in reading extended text.

Dehaene’s theories stem from both his clinical practice, treating patients with brain damage and his knowledge of and use of the different types of brain imaging now available.  The former aspect leads to one of the most annoying aspects of this book which is its language in relation to dyslexia.  In an otherwise useful series of chapters on the nature of dyslexia Dehaene persists in using the medical model of “impairment”, suffering and “rehabilitation for dyslexia” (p.214), terminology that really grates on the nerves.  Dehaene is also clearly wooed by the powerful faction of researchers who favour an exclusively phonological definition of dyslexia as an “impairment of grapheme-phoneme conversion” (p. 195).  To give him credit, however, Dehaene recognises a minority of dyslexic children who have visual difficulties and/or a joint deficit of vision and language.  He outlines his own theory of dyslexia in general (as a disruption to the early creation of the brain’s networks) and visual dyslexia in particular (as a failure of the brain circuitry to sufficiently specialise to left hemispheric circuitry for reading, causing various aspects of left-right confusions).

Dehaene’s espousal of phonological disorders for most aspects of dyslexia spills over into his foray into pedagogical advice.  This is another area for disquiet.  While rather patronisingly urging that “teacher autonomy [should be] safeguarded” (p.269), he lays down the law extremely dogmatically in advocating a diet of phonics for all beginner readers.  This is in conflict with his much more promising assertion that “every teacher bears the burden of experimenting carefully and rigorously to identify the appropriate stimulation strategies that will provide students’ brains with an optimal daily enrichment” (p.191).

Dehaene does acknowledge that a child’s brain is different from an adult’s when it comes to reading.  With a child, the teacher has to work systematically and sequentially to help build up the most efficient hierarchy of neural connections to make reading work, while the brain is at its most plastic.  With competent adult readers the global and parallel processing system is already there.  The question for adult literacy, then, which Dehaene does not directly address, but offers some insight into, is how to make the best of some possibly muddled brain wiring in adults who struggle with reading.  In my view, it is not relevant to go back to the hierarchical system of tuition, but to look for where an individual’s strengths indicate possible compensatory strategies.  Dehaene offers hope that by active teaching we can actually still change the pattern of neural connections in an adaptive way.  After all, all those centuries ago, our brains adapted to the new stimulus of the written word.