Developmental Dyslexia

Stuart G. Andrewes & Karen E. Waldie, Department of Psychology, The University of Auckland.

Developmental Dyslexia (specific reading disability) is characterised by moderate to extreme difficulties in acquiring reading related skills in spite of normal intelligence and adequate educational opportunities and affects around six per cent of the population.

Dyslexia has been extensively researched in the academic literature.

Contrary to popular mythology, seeing letters/words backwards is not a defining feature of the disorder.

Rather, deficits in phonological processing are widely acknowledged as the core deficit. These can be seen most often in difficulties in the explicit ‘sounding out’ and blending of letters and words.

These difficulties can be exhibited as either inaccuracies (substitution of incorrect words that are similar or the mixing of letter orders in words) and/or processing deficits (slow speed/labour intensive reading).

Phonological processing skills are thought to be specialised to the left side of the brain, specifically within two ‘dorsal’ areas of the cortex called the inferior frontal gyrus and the angular gyrus (see Figure 1A).

Research from The University of Auckland has shown that adults with dyslexia recruit different brain areas when reading in comparison to non dyslexic adults (see Figure 1B).

Children (and some adults) with dyslexia will often use external cues (such as pictures, body language and copying of others in the class/setting) to help give a response to a reading or spelling question. In some, if not most cases, dyslexic individuals will engage in avoidance behaviour which may be charcterised by a reluctance to engage in reading related activities. In extreme cases this can lead to skipping classes or antisocial behaviour in the classroom.

Dyslexia is not a sentence to illiteracy. With appropriate support, dyslexic individuals can develop accurate reading though reading speed often remains slower and spelling remains a challenge.

For general information about dyslexia see: http://www.dyslexiafoundation.org.nz. For an article from a NZ perspective, see: Thompson, G.B., McKay, M.F., & Fletcher-Flinn, C.M. (2004). New theory for understanding reading disability. Australian Journal of Learning Disabilities, 9, 3-7.

RESEARCH STUDY: Dyslexia has a high rate of co-occurrence with other learning disabilities such as dyscalculia (mathematics disability). Why is this, and how does it effect identification and remediation? We are investigating these questions in an on-going project led by Dr. Karen Waldie and Dr. Anna Wilson (University of Canterbury). We are particularly in need of adult volunteers with reading difficulties and no mathematical difficulties (contact LDstudy.auckland@gmail.com). All participants will receive a detailed copy of their test results.

Figure 1. fMRI allows us to map increases in oxygenated blood flow that accompany local synaptic activity during cognitive tasks. The bright areas indicate statistically significant areas of activation. In both A and B, the image shows a coronal section of the brain whereby the left side represents the left hemisphere and the right side represents the right hemisphere.

Modified from Waldie, KE. Introduction to developmental neuroscience: Neurological development and the mechanisms underlying reading. In Jason Low and Paul Jose (Eds., Part 2, Ch.3 pp.20-30), Lifespan Development: The New Zealand Context. Auckland, Pearson, 2005.

Research by Karen Waldie from The University of Auckland has shown that phonological processing skills are specialised to the left side of the brain, specifically within two “dorsal” areas of the cortex called the inferior frontal gyrus and the angular gyrus (see Figure 1A) whereas adults with dyslexia recruit different brain areas when reading (see Figure 1B).