Do You Have a Touch, or More Than a Touch, of Dyslexia?

Have you heard the one about the agnostic insomniac dyslexic who stayed awake pondering the existence of Dog? If not, you’ve got a fresh joke for the next cocktail party. But when you spin this yarn over a glass of Chablis, be sure to add that it’s flawed: Dyslexia is not about letter reversals. Rather, it is a brain disorder that makes it difficult for a dyslexic to connect the sound components of speech, which are called phonemes, to the written letters representing those sounds. A few dyslexics may see letters reversed, but more often the problem can’t be so easily described.

Recently, researchers Albert Le Floch and Guy Ropars at The University of Rennes in France discovered that the reading disorder may arise because of a lack of asymmetry between retinas of each eye of afflicted individuals. In the human fovea, the central part of the retina with highest visual acuity (where we focus on text), humans have a small patch of blue-cone free receptors called the Maxwell Spot. In most people, the shape of this spot differs between the two eyes—circular in one eye and slightly elliptical in the other. But in Dyslexics, the two spots are typically the same shape. Le Floch and Ropars speculate that when the Maxwell spots have identical shapes in the two eyes, the brain might confuse and superimpose images, creating a type of double vision, or mirror reversed vision, that makes it hard for brains of dyslexics to convert text into the sound of words

To understand dyslexia better, consider the contortions the brain must go through in order to read and understand the word rutabaga. First, it must resolve the word’s contours into letters (perhaps more difficult in Dyslexics due to Maxwell Spot symmetries), and then match these letters to the individual phonemes the letters represent. Next, the brain stitches the phonemes together into the sound of rutabaga, then retrieves the word from memory to comprehend it. In English, the more than 40 phonemes outnumber letters of the alphabet because letters can express multiple sounds. For rutabaga, a normal brain would select the phonemes /r/, /u/, /t/, /ə/, /b/, /e/, /g/, /ə/. The t sounds similar to a d, while the pronunciation of the letter a, which occurs three times in the word, requires two different phonemes. The first and last a take on the sound of the a in sofa, while the second a sounds like the long a in bait.

The phonemes in rutabaga illustrate how complex reading actually is. Now imagine trying to navigate this lexical jungle while lacking the ability to match the letter a to the sound of /ə/. The brain’s method of unlocking the meaning of a word—silently sounding out /rut/—is disrupted for a dyslexic, thus creating a challenge.

Research has shown that dyslexia is not an all-or-nothing reading disorder, but comes in many "flavors" from mild to severe. You may have had mild or moderate dyslexia and never realized it. To see if you might have dyslexia to one degree or another, try these tests.

Test #1

1. Do you have difficulty reading aloud?
2. Are you a bad speller?
3. Do blood relatives of average or higher intelligence have trouble learning? (Le FLoch and Ropars also discovered that Maxwell spot symmetry runs in families, incidentally)
4. Do you struggle to follow written but not oral directions?
5. When reading, do you often have to go back over the same word several times before understanding it?
6. Did you have problems learning a foreign language?

Answering yes to more than two questions means you should try the next test to see how well you connect letters to phonemes.

Test #2

Below are 20 nonsense words. If spoken aloud, nine of them sound like real words; baik, for example, stands for bake. Without speaking the words out loud, figure out which ones correspond to real words. Missing more than three could mean you have some degree of dyslexia and could benefit from further evaluation. The answers are upside down at the end of the experiment.

zam lep crope bete mord

sed rool peze frire blone

baik calp hib masp thoe

vust praid blut karn crasp

Source: Eric Haseltine

If tests lead you to believe you might have dyslexia, you’re in good company; dyslexia affects up to15 percent of us and is a leading cause of reading disabilities. New teaching methods that emphasize the sounds of language can help dyslexic readers attain normal reading skills.

Some neuroscientists believe that dyslexics are more creative than the average person—Albert Einstein and William Butler Yeats had the disorder—because the brain structures normally devoted to processing language rewire themselves, thereby priming the mind to cook up novel ideas.

If you are curious about additional ways your brain differs other people's, check out the "What about you?" section of my new book, Brain Safari.

This material was excerpted from Brain Safari, and from my Neuroquest column in Discover Magazine.