Strategic control in developmental dyslexia

Two types of developmental dyslexia are commonly distinguished. Children suffering from one type (e.g. surface dyslexia) read slowly and typically sound out the words during reading and children with the other type (e.g. phonological dyslexia) read at a normal rate but make many word substitutions. Several authors (e.g. Castles & Coltheart, 1993) have proposed that the existence of the two types of dyslexia is due to a deficiency in or a relative inefficiency of either of the two routes postulated in the dual-route theory of reading. The purpose of the present study was to assess whether dyslexic children have strategic control over the two reading routes. Twenty dyslexic children were asked to read aloud word lists and texts as fast or as accurately as possible. When reading fast as opposed to accurately, children showed an increase in number of word substitutions and a decrease in number of responses with sounding-out behaviours: In other words, they behaved more like phonological dyslexics in the fast condition, and more like surface dyslexics in the accuracy condition. Thus, the different symptoms commonly used as a basis for the classification of developmental dyslexia into dyslexic syndromes do not only reflect underlying deficits, but also strategic choices.