title: Are the literacy difficulties that characterize developmental dyslexia associated with a failure to integrate letters and speech sounds?
abstract: The 'automatic letter-sound integration hypothesis' (Blomert, ) proposes that dyslexia results from a failure to fully integrate letters and speech sounds into automated audio-visual objects. We tested this hypothesis in a sample of English-speaking children with dyslexic difficulties (N = 13) and samples of chronological-age-matched (CA; N = 17) and reading-age-matched controls (RA; N = 17) aged 7-13 years. Each child took part in two priming experiments in which speech sounds were preceded by congruent visual letters (congruent condition) or Greek letters (baseline). In a behavioural experiment, responses to speech sounds in the two conditions were compared using reaction times. These data revealed faster reaction times in the congruent condition in all three groups. In a second electrophysiological experiment, responses to speech sounds in the two conditions were compared using event-related potentials (ERPs). These data revealed a significant effect of congruency on (1) the P1 ERP over left frontal electrodes in the CA group and over fronto-central electrodes in the dyslexic group and (2) the P2 ERP in the dyslexic and RA control groups. These findings suggest that our sample of English-speaking children with dyslexic difficulties demonstrate a degree of letter-sound integration that is appropriate for their reading level, which challenges the letter-sound integration hypothesis.
authors: Department of Psychology, University of Leeds, UK.
authors: Hannah M
authors: HM
authors: Nash
authors: Division of Psychology and Language Sciences, University College, London, UK.
authors: Debbie
authors: D
authors: Gooch
authors: Division of Psychology and Language Sciences, University College, London, UK.
authors: Charles
authors: C
authors: Hulme
authors: The MARCS Institute, University of Western Sydney, Australia.
authors: Yatin
authors: Y
authors: Mahajan
authors: ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Australia.
authors: Genevieve
authors: G
authors: McArthur
authors: Division of Psychology and Language Sciences, University College, London, UK.
authors: Kurt
authors: K
authors: Steinmetzger
authors: St John's College, University of Oxford, UK.
authors: Margaret J
authors: MJ
authors: Snowling
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D004410:Dyslexia / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D000067010:Literacy; D011930:Reaction Time; D013067:Speech Perception