A dual-route perspective on poor reading in a regular orthography: evidence from phonological and orthographic lexical decisions.

Impairments of the lexical and the nonlexical reading route were examined for German-speaking dyslexic readers by measuring accuracy and speed of phonological and orthographic lexical decisions. Different from English-based findings, we found little difficulty with the phonological distinction between pseudohomophones and nonwords, but a major difficulty with the orthographic distinction between words and pseudohomophones. Subtyping identified pure surface dyslexia cases but no case of pure phonological dyslexia. Dyslexic speed impairments were traced to three loci in the dual-route model: an impoverished orthographic lexicon, and slow access from orthographic to phonological lexicon entries (lexical route) and from graphemes to phonemes (nonlexical route). A review of distal cognitive deficits suggested that the orthographic lexicon is affected by phonological deficits and that the slow functioning of the lexical and the nonlexical route reflects a general visual-verbal speed impairment and not a purely visual-attentional deficit.