Reaction times and dyslexia.

Five groups of children, including two groups of dyslexics (aged 15 and 11 years), were tested on simple reaction, selective choice reaction, and lexical decision tasks. In simple reactions to a pure tone, the dyslexic children responded as quickly as their chronological age controls and significantly faster than their reading age controls. In selective choice reactions to pure tones, the dyslexic children were significantly impaired compared with their chronological age controls and no faster than their reading age controls. This speed impairment obtained even though a selective choice reaction task has only one positive response. In "by-item" analyses of lexical decisions to spoken words, the dyslexic children were significantly impaired compared even with their reading age controls. The pattern of results suggests that at least two factors contribute to slowness of dyslexic children: a general deficit reflected in slower stimulus classification speed and a linguistic deficit reflected in slower lexical access speed.