Sensitivity to voicing similarity in printed stimuli: effect of a training programme in dyslexic children

Abstract

Dyslexic children exhibit great difficulties in acquiring reading skills, despite adequate intelligence and instruction, and in the absence of any obvious neurological or sensory disorders. Both phonological and surface dyslexics are impaired in phonological skills (Sprenger-Charolles, Col! e, Lacert, & Serniclaes, 2000), but the origin of these disabilities is controversial. According to the ‘rapid processing hypothesis’, phonological impairments in dyslexia stem from an auditory deficit in the processing of brief and/or rapidly changing acoustic events, which compromises phoneme discrimination, and the acquisition of metaphonological skills and grapheme–phoneme correspondence rules (Nagarajan et al., 1999; Tallal, 1980). According to the ‘linguistic hypothesis’, auditory deficits and language disorders may be associated but are not causally related (Cornelissen, Hansen, Hutton, Evangelinou, & Stein, 1998; Nittrouer, 1999; Rosen, 2003). The evidence for this view is twofold. First, many studies demonstrated the existence of a speech-specific impairment in dyslexia (Mody, Studdert-Kennedy, & Brady, 1997; Rosen & Manganari, 2001). Second, the processing of short and/or rapidly varying acoustic signals may not be the fundamental problem in dyslexia (Bradlow et al., 1999). Intensive training with artificially slowed speech did not improve reading and phonemic awareness, compared with training on unmodified speech (Rey, De Martino, Espesser, & Habib, 2002). Whatever the origin of linguistic disorders in dyslexic children, it is generally agreed that the core deficit is phonological. In this paper, we ask which phonological mechanisms and which aspects of phonological knowledge are impaired in dyslexia. We assume that this impairment relates to the phonetic underpinnings of phonemic knowledge. This hypothesis is supported by recent experiments on the effect of phonetic similarity in reading. ARTICLE IN PRESS