Dyslexia is becoming clearer
Over the years, I have followed research into dyslexia. What there was amounted to a number of theories and occasional real data. This was true when I was young and it is still true. The way I judged the news was how much it conformed with my experience.
The first theory I encountered was a repeat of the theory of left-handedness (I followed that too because I am left-handed as well as dyslexic): there is obviously nothing physically wrong with these children, they are not stupid or lazy, and so they must be ‘ornery’ probably because of their mothers.
Next was the argument that there was nothing wrong with their ability to speak or understand speech, therefore it must be their vision that was faulty and makes reading and writing a problem. This theory has not died completely. Recently it was featured in a new font for dyslexics. It did improve their ability to read, but it turned out to also improve the reading of non-dyslexics. This is what happened with coloured transparent plastic sheets. They helped dyslexics but then it was shown that it helped normal readers too.
I am sure that there are various types and degrees of dyslexia. The definition is wide enough to cover many conditions. Left handed dyslexics may have different details in their condition then right handed ones, ditto boys and girls, ditto those learning very phonetic languages from those learning a language like English. If pushed, I would even agree that some dyslexic may have predominantly visual problems, but not many.
If it is not a language problem and not a visual problem, it must be a hearing problem. In normal tests of hearing, dyslexics are not abnormal. They hear the frequencies and volumes that normal people hear. How can someone both hear and not hear the nature of a spoken word? That became somewhat clear when it was found that the right and left hemispheres of the brain have a division of labour. (This is not right-brained/left-brained silliness, but about cooperation between different areas.) Where language sound is concerned, the right hemisphere deals with syllables and the left with individual sounds represented by letters in the written language. So it is possible to understand and speak using syllables rather than phonemes.
It seems that most people find it hard to think in terms of syllables but it really rings true to me. If you think of the syllable as a single sound in the form of a vowel that has its beginning, ending or both modified then it can be perceived as a unit and produced as one sound. I remember having difficulty with vowels as a child. My spelling was ridiculous so it was hard for anyone to guess what I was writing but one thing was consistent – vowels were very rare to non-existent. I had been in school almost two years when I was told that every word had to have a vowel, and what the vowels were. Great surprise but of little use! It was difficult to take syllables apart and find the vowels. I understood the sounds of the consonants alone but had difficulty identifying them in words. The phonetic languages have individual letters but there are other older languages that use syllable symbols rather than letters. It is a idea that should not be a surprise. But this syllable rather than phoneme mode of dyslexics never really became a popular theory.
Experiments showed that dyslexics had difficulty perceiving very fast changes in sound. Sounds that were 10 milliseconds or shorter simply could not be properly heard. They reached the brain from the ears but were not processed as speech sounds. Many consonants are very short sounds. This fits with another fact – many dyslexics have very poor reaction times. Mine are terrible. Dyslexic children have to be taught to recognize sounds that are so short they can barely perceive them. I doubt that we ever learn to hear the very shortest consonants except in the way they modify vowels.
Because dyslexia seems to have an inherited tendency, researchers looked for anatomical and connective differences in the brain. Some were found. There was a difference in the connections between the two hemispheres at the level of the auditory areas and there was a difference in the bundles of nerves connecting the auditory area with the language areas at the front of the brain. Differences in the activity of various parts of the language area were also found. However, there was a chicken and egg problem. For example, did the fault in connection between the two hemisphere result in an problem with processing sound, or, did the fault in the sound processing areas result in the lack of communication between the two hemispheres? Do the differences in activity between dyslexic and normal children occur because they learned to read in a different way? It is not that clear what the evidence is actually showing. Two things fit with my experience. First, when I learned to read and spell, it always seemed like there was a gap or a wall that had to be overcome and I was never successful at getting through in a straight forward way. I had to find a path to go around the obstacle, sometimes away around. That implied a missing communication channel between the back and the front of the brain. Second, my brother had a cleft palette and this lack of contact between the two sides of the head is associated with problems with the nerves connecting the two hemispheres and it is an inherited tendency. I have an unusually high palette and some traces of a poor connection. One of the genes that is common in dyslexics is involved in the growth of nerves across the mid-line of the brain.
People have changed their attitudes somewhat to dyslexia. As long as they do eventually learn to read and write (which they mostly do these days) they are no worse for it. Some say they have greater talents but that is probably not statistically valid. I have never thought I was without the dyslexic architecture of my brain – it has not changed – I am not ‘cured’ but adapted with many coping skills.