Dyslexia, another model and a therapy

I suspect my readers have figured out I suffer from dyslexia, well regarding that this work by Gadi Geiger, Jerry Lettvin, and others is thought provoking.

They found interesting visual test you can run to test for dyslexia. You have the subject stare at a dot a screen, and then you briefly flash a single letter in place of the dot. At the same time you also flash another letter a some distance away from the centered letter. You then ask the subject to enter the two letters. A series of these samples allows you to build a map of how the subject’s visual focus ranges across his visual field.

Not surprisingly people skill at catching that second letter varies with how far from the centered letter it appears. But dyslexics, apparently, tend to drop off more rapidly in near the center while they are better at catching the letters further off from the center. This matches up nicely with the experiance of dyslexia, i.e. that it’s difficult to see the individual words and one is often skittering about on the page noticing items that if you could manage your attention more successfully would be ignored. I also am amused by how this ties into some of the stuff I’ve been thinking recently about attention managment.

They also noticed that the focus of attention across the field of vision is shaped differently for people who read English v.s. Hebrew (which is read left to right).

They also noticed that dyslexics who have managed to learn to be effective readers, like me, will have one mode when they are attentive and another when they are fatigued. Boy I’m familiar with that syndrome.

Based on this test, and optimism about the plasticity of the brain, they invented a little therapy to try. They cut a hole in an index card so that only a dozen letters of text were visible and asked some kids with dyslexia to try reading through that window for a few weeks.  This turned out to be amazingly effective! Presumably it trains the visual system to attend more closely to the material near the point were your reading.

Update: Having attended a talk by Geiger it appears that description is missing a critical element; i.e. they also asked the kids to engage in an art/craft activity that involved fine motor and eye coordination.  Follow on studies have indicated this is a necessary component of the therapy.  Why exactly they included this complementary activity is unclear to me, but it helps explain why nobody stumbled on the therapy before.  Gadi suggested it was an intuitive move; possibly triggered by some studies done in the years before this.  Those studies showed that active hand/eye interaction made a substantial difference in people’s ability to compensate for the effects of silly goggles that did things like shift your vision six inches to the right.

I want to note that this approach doesn’t attempt to treat the cause of dyslexia. The visual field anomaly is a symptom and the therapy treats that symptom. Dyslexia has other symptoms, for example there are significant phonetic aspects which make it miserable to learn a foreign language, recall names, or repeat words you hear.

Reading thru a window also used in some speed reading schemes; see for example this demo of RSVP and if you like that try this this Firefox extension.

I wrote an emacs mode that simulates their index card.

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