The right and wrong places to look for the cognitive locus of reading disability.

A coherent conception of dyslexia has been difficult to arrive at because research findings have continually created logical paradoxes for the psychometric definition of reading disability. One such paradox is that cognitive research has undermined the assumption of specificity in the definition of dyslexia. The assumption of specificity is the underlying premise that the cognitive problems characteristic of the dyslexic child are reasonably specific to the reading task and do not implicate broader domains of cognitive functioning. This paper demonstrates how to develop hypotheses about the cognitive deficits of dyslexic children that do not undermine the assumption of specificity. Phonological awareness is explored as one candidate process.It is argued that in order to avoid the pitfalls surrounding the assumption of specificity three things are important: 1) We must understand the operation of Matthew effects in education (rich-get-richer and poor-get-poorer effects); 2) Strict psychometric criteria must be used to define dyslexia; 3) We must continually be aware that dyslexia does not demarcate a discrete category, separate from other groups of poor readers, but represents the outcome of the application of an arbitrary criterion in a continuous distribution.