Lallier, M. 1 , Donnadieu, S. 2, 3 & Valdois, S. 2, 4
1 Basque Center on Cognition, Brain and Language (BCBL). Donostia. Spain
2 Laboratoire de Psychologie et Neurocognition, Grenoble, France
3 Université de Savoie, Chambéry, France
4 Centre National de la Recherche Scientifique, Grenoble, France
It has been suggested that auditory and visual sequential processing deficits contribute to phonological disorders in developmental dyslexia. As an alternative explanation to a phonological deficit as the proximal cause for reading disorders, the visual attention span hypothesis (VA Span) suggests that difficulties in processing visual elements simultaneously would lead to dyslexia, regardless of the presence of a phonological disorder. In the present study, we assessed whether deficits in processing not only visual but also auditory elements displayed simultaneously is linked to dyslexia associated with a VA Span impairment. Sixteen children with developmental dyslexia and 16 age-matched skilled readers were assessed on visual and auditory search tasks. Participants were asked to detect a target presented simultaneously with 4, 10 or 16 distracters. Target detection performance was impaired in the dyslexic group compared to the control group in the visual modality only. Within the dyslexic group, both visual and auditory target detection measures strongly correlated with irregular word reading accuracy. They also were associated with VA Span but not phonological skills. The present data suggests that visual and possibly auditory simultaneous processing engaged in search tasks contribute to dyslexia via VA Span and/or orthographic knowledge deficits. Implications of the results for the "temporal sampling framework" of dyslexia in the auditory (Goswami, 2011) and the visual modalities are discussed, focusing on the links between the sequential and simultaneous dimensions of processing involved in reading, and the oscillatory frequency bands supporting cerebral processing.