Dehaene on the Brain


It has been a few years since I blogged about the work of Stanislas Dehaene.  You can access many of the crucial publications from this prolific cognitive neuroscientist here, with his work of particular interest to us centering on visual aspects of the brain – particularly those involved in reading.

wiseSince 2009 there has been an annual international summit known as WISE: World Innovation Summit for Education.  It is billed as a multi-sectoral and action-oriented platform for innovation in education that connects innovators, nurtures new ideas, and recognizes and supports successful initiatives that are helping revitalize education.  In 2012, Stanislas Dehaene was invited to present a synopsis of his work on how the brain learns to use its visual areas in concert with language areas.

There is much to enjoy about Professor Dehaene’s presentation – and he covers this in the first 18 minutes.  If you’re tight for time please watch and listen to that part of the video; the second half of the video dedicated to Q and A isn’t as informative.  At the 10 minute mark he gives a very nice explanation about the need for all children to overcome the tendency to have difficulties with the laterality and directionality of print as related to writing and reading in contrast with the symmetry of faces or objects.  He goes on to note that the massively parallel operations used in letter processing for reading can give the illusion of “whole word reading”.

Phonetic FocusIt has long been my contention that a key element of visual processing in reading is “sight word recognition”, but by that I mean recognizing patterns.  As Professor Dehaene notes, English is the most opaque and irregular alphabetic language in the world.  Yet  what most successful readers master are the probability patterns that allow us to master the 70% of the printed language that is regular, and to take better educated guesses at roots and word families.  This is part of what Sarah Cobb attended to years ago with the vision therapy procedure of phonetic focus charts in encoding word families.

 

I would like to add another observation that bolsters Professor Dehaene’s argument that visual global shapes are not used in reading words in print.  Take a look at the passage below, and begin reading it silently.

Reading 2

You may not notice anything unusual about the print, particularly if you are a good reader and engaged in comprehending what you are reading.  However I may be able to gain your awareness of illusory contours that occur if you attend to the global patterns of the print rather than to the flow of reading.  Look at the top line of print below and without moving your eyes see if you notice something unusual occurring in the lower region of the page, angling from the right margin inward.

Reading

 

It begins the line below “The moment you start connect-“.  See it now?  Because of the overload of the number of similar letters and the spacing of the words, your visual system has formed a descending staircase proceeding at roughly a 45 degree angle over the course of the next six lines.  If you look directly at that area you aren’t as likely to be aware of the illusion as you are when you look above or below the area.  Now that you’ve seen it, if you go back to the first image that has the full page it should be more apparent to you.

This dovetails with Professor Dehaene’s theory of neuronal recycling, and how the visual parts of the brain transform their sensitivity for pictorial representation in the brain and re-allocate some of that real estate for grapheme-phoneme correspondence.  Those individuals who remain very “visual” in the sense of being more pictographic wind up with illusory contours that we can’t fully imagine.  The tension between the object and face recognition real estate transforming to the grapheme/phoneme correspondence can literally result in visual instability as the brain toggles between two modes of processing, print vs. pictorial.  Other visual instabilities such as ocular motor or binocular compounds this tension in visual input.  I believe that much of what we do in vision therapy helps struggling readers balance this tension in a more effective way.  With these thoughts in mind, go back and view Professor Dehaene’s first 18 minutes.

 

 

 

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