There is always controversy surrounding the question, what causes dyslexia? It has baffled teachers and psychologists for over a hundred years. David Morgan examines what he sees as some of the possible causes.
What causes dyslexia?
In my experience there are seven main causes of reading and spelling difficulty:
A conventional reader processes written text first through the eyes and then in the visual cortex. The brain then passes that information to the auditory cortex where the letters are mapped to their sounds and blended into words.
The words are passed to the linguistic cortex where the meaning is comprehended. Finally, the words arrive at the prefrontal cortex where they are stored and linked to the rest of the sentence.
One possible answer to the question of, what causes dyslexia? Is that 80% of struggling readers do not engage their auditory cortex, skipping straight from the visual input to the final storage stage. This leads to guessing and frustration as vocabulary grows more complex.
2) Eye-Tracking Weakness:
Normally a reader’s eyes perform a refined jump from left to right over each word cluster. This is called a saccade. Some struggling readers have a weakness in the neural feedback loop controlling eye muscle movement. This makes it very hard to focus accurately on a word in a sentence.
The correct eye-tracking exercises will usually fix this neural weakness.
3) Irlen Syndrome:
The human eye has a great visual sensitivity to changes in colour and brightness in order to identify patterns. In some cases what causes dyslexia is the struggling reader will have an over-sensitivity to black text on white background.
This causes the words to shimmer or move around on the page. The problem can be alleviated with coloured films to soften the level of contrast.
4) Poor short-term memory:
Learning to read requires a lot of short-term memory capacity. Words are broken into sounds, which then have to be held in memory to be turned into a word, which then have to be held in memory to be placed in a sentence, which then…etc!
Some struggling readers have a limited short-term memory capacity, recalling more than 4 numbers in a sequence can be difficult. This causes comprehension problems and difficulty with decoding long words.
5) Fluency Block:
A conventional reader uses a part of their brain called the letterbox cortex to recognise common letter groupings. Amazgainly you aer able to raed scarblmed txet quite flnuetly, due to this function.
Some struggling readers bypass their letterbox cortex when reading, instead using visual memory to store letter groupings. This causes the reader to be able to decode quickly, but they never really develop fluency or smoothness.
6) Attention Deficit:
Struggling to focus when reading, fidgeting, and being easily distracted are all symptoms of attention deficiency.
However focusing for long periods of time is easy for anyone when a task is enjoyable. There needs to be a greater emphasis on making learning to read Fun.
7) Stress Spirals:
Reading can be a very stressful process for dyslexic people? As stress levels rise higher brain function is shut down. Therefore stress can inhibit reading practice. The struggling reader associates stress with reading practice and tries to avoid it in the future.
So what causes dyslexia? Well a dyslexic reader may have one or several of the above factors. The key to making reading or spelling easier is to identify the cause and then find ways to address it. That is what we specialise in at Easyread.
David Morgan is CEO of Oxford Learning Solutions and creator of the Easyread System, www.easyreadsystem.com.