What Really is Dyslexia?

There are several and varied definitions of dyslexia but the problem with many of these are that they often include components that have little or nothing to do with the key concept.

In a paper entitled Defining Dyslexia, published in the latest issue of the Journal of Learning Disabilities (the leading scientific journal in the field of learning difficulties) Prof. William Tunmer and Dr Keith Greaney from Massey University draw on contemporary theory and research on reading development, reading difficulties and reading intervention to develop an up to date scientific conceptualization of dyslexia.

In the paper the authors present arguments and evidence in support of what they maintain are four key components of the definition of dyslexia, which include: (1) persistent literacy learning difficulties; (2) in otherwise typically developing children; (3) despite exposure to evidence-based literacy instruction and intervention; (4) due to an impairment in the phonological domain of language.

The authors claim that the over-riding problem affecting nearly all children with literacy learning problems (including dyslexics) is impairment in the phonological processing skills (e.g., decoding, spelling, phonological awareness) required to learn to read and write.

The authors also compare their definition of dyslexia to one recently proposed by the NZ MoE.

The ministry (like the Dyslexia Foundation of NZ) prefer a “broad spectrum” definition, which, according to Prof. Tunmer and Dr Greaney, encompasses other components that have little or nothing to do with dyslexia.

The full reference for the article is: Tunmer, W, & Greaney, K. (2010). Defining Dyslexia. Journal of Learning Disabilities, 43 (3), 229-243.