kitchen table math, the sequel: Dehaene's Reading in the Brain

Sunday, April 4, 2010

Dehaene's Reading in the Brain

I thought I'd slapped a post up here in January when I got the book, but evidently not.

Fascinating interview with Stanislaus Dehaene, author of Reading in the Brain

On the shapes of letters:

In the case of reading, the shapes of our writing systems have evolved towards a progressive simplification while remaining compatible with the visual coding scheme that is present in all primate brains. A fascinating discovery, made by the American researcher Marc Changizi, is that all of the world's writing systems use the same set of basic shapes, and that these shapes are already a part of the visual system in all primates, because they are also useful for coding natural visual scenes. The monkey brain already contains neurons that preferentially respond to an “alphabet” of shapes including T, L, Y. We merely “recycle” these shapes (and the corresponding part of cortex) and turn them into a cultural code for language.
How literacy changes the brain.
We are starting to do brain-imaging experiments in illiterates, and we find that this region, before it responds to words, has a preference for pictures of objects and faces. We are also finding that this region is especially attuned to small features present in the contours of natural shapes, such as the “Y” shape in the branches of trees. My hypothesis is our letters emerged from a recycling of those shapes at the cultural level. The brain didn't have enough time to evolve “for” reading – so writing systems evolved “for” the brain!

On the scientific bankruptcy of whole-language (and balanced literacy)

In the case of reading, very concretely, as I explain in the book, we now have plenty of evidence that the whole-language approach has nothing to do with how our visual system recognizes written words – our brain never relies on the overall contours of words, rather it decomposes all of its letters and graphemes in parallel, subliminally and at a high speed, thus giving us an illusion of whole-word reading. Experiments even suggest that the whole-language method may orient learning towards the wrong brain region, symmetrical to the visual word form area in the right hemisphere! We need to inform our teaching with the best brain science – and we also need to develop evidence-based education research, using classroom experiments to verify that our deductions about teaching methods actually work in practice.

On dyslexia

This isn't fully known, but I was intrigued by recent research which indicates that dyslexic children and adults can be better on tasks of symmetry detection – they have a greater ability to notice the presence of symmetrical patterns, and the evidence even suggests that this was helpful in a group of astrophysicists to detect the symmetrical spectrum of black holes!

My theory is that mirror recognition is one of the functions that we have to partially “un-learn” when we learn to read – it is a universal feature of the primate brain that is, unfortunately, inappropriate in our alphabet where letters p, q, d and b abound. By somehow managing to maintain this ability, dyslexics might be at some advantage in visual, spatial or even mathematical tasks.

1 comment:

Catherine Johnson said...

Thanks for posting this!

I'd been planning to do it myself --