Reading and dyslexia

Click to expand

It has been found that one of the most important characteristics for predicting difficulty with reading in children is difficulty with phonological processing. That is, children who have trouble breaking down words into sounds (bug= /b/ + /ʌ/ + /g/) have greater difficulty learning to read. This is because a reader who cannot identify individual sounds cannot make sense of sound-spelling correspondences; they cannot tell what a letter is meant to represent (Richlan et al., 2011; Wagner & Torgeson, 1987). This also impacts a person’s ability to process words orthographically; a person who cannot analyse a word cannot learn to recognise it by sight (McCandliss & Noble, 2003).

Earlier it was explained that, for typical readers, different parts of the brain are associated with different parts of the reading process. However, it has been found that these centres are not activated in the same way for readers with dyslexia: the areas responsible for rule-based analysis of words (in particular, phonological processing) and whole word recognition (orthographic processing) are under-activated (McCandliss & Noble, 2003; Pugh et al., 2000; Richlan et al., 2009). Using magnetic resonance imaging (MRI) technology, Shaywitz et al. (2003) observed differences in brain activity of young adults with a persistently poor reading compared to non-impaired readers while performing rhyming tasks. The images below roughly illustrate these differences.

While there is still more to learn, this kind of research provides important evidence that dyslexia is a very real phenomenon with neurological causes.

Click to expand

Areas of brain activity observed in persistently poor readers (left) and non-impaired readers (right) while performing rhyming tasks.

Activity

Question

Thinking about the basic underlying causes of dyslexia mentioned above, what kind of instruction do you think would be most effective for helping a child with dyslexia learn to read?

Answer

According to Shaywitz et al. (2004), “evidence based phonologic reading intervention” leads to observable differences in the brain (p. 930). In their controlled experimental study, Shaywitz et al. (2004) provided second and third grade children with dyslexia 50 minutes of systematic phonological instruction each day for eight months, teaching them how to break down words into sounds and to associate sounds with their spellings. Following the intervention, these children demonstrated greater improvement in measures of reading ability relative to a group of children with dyslexia who did not receive additional phonological instruction.

It was also found through functional magnetic resonance imaging (fMRI) that the phonological intervention group experienced important and lasting changes in parts of the brain associated with reading. Interestingly, it was found that the part of the brain associated with rapid recognition of whole words (orthographic processing) had continued to develop after one year, suggesting that developments in phonological processing ability also increased the children’s capacity to learn new words by sight.

Activity

Please watch the following video: