Dissociations between developmental dyslexias and attention deficits.

We examine whether attention deficits underlie developmental dyslexia, or certain types of dyslexia, by presenting double dissociations between the two. We took into account the existence of distinct types of dyslexia and of attention deficits, and focused on dyslexias that may be thought to have an attentional basis: letter position dyslexia (LPD), in which letters migrate within words, attentional dyslexia (AD), in which letters migrate between words, neglect dyslexia, in which letters on one side of the word are omitted or substituted, and surface dyslexia, in which words are read via the sublexical route. We tested 110 children and adults with developmental dyslexia and/or attention deficits, using extensive batteries of reading and attention.

Developmental surface dyslexias.

Individuals with surface dyslexia read via grapheme-to-phoneme conversion due to a deficit in the lexical route. A deficit in the lexical route can be caused by impairments at several different loci. In the current study we identify three subtypes of developmental surface dyslexia, each caused by impairment at a different locus on the lexical route, and each showing a different pattern of performance in various tasks.