Impaired access to phonological representations in dyslexia: New insight from ERPs in picture and letter naming tasks

Mahé, G. 1 , Zesiger, P. 2 & Laganaro, M. 2

1 SCALab - UMR CNRS 9193 - University of Lille, France
2 University of Geneva, Switzerland

In a previous ERPs study investigating reading aloud processes, we show edevidence of differences between dyslexic and expert adult readers in the phonological processing stages. The aim of the present study was to further characterize these phonological deficits in dyslexic readers in two non-reading tasks involving similar phonological processes to reading aloud. 40 university students took part to the experiment: 20 dyslexic and 20 adult expert readers performed a picture naming and a letter naming task under ERP recordings. Spatio-temporal segmentations were performed to determine whether some processing stages differed in nature or in duration between the two groups in each task. Results revealed only minor differences between the two groups in picture naming. In letter naming, spatio-temporal segmentations revealed different topographic maps between the two groups at the N170 time interval and a longer duration of a map related to phonological processes in dyslexic compared to expert readers. Taken together the present findings provide new insight concerning the characteristics of phonological access in dyslexic readers, with larger differences in alphanumeric compared to non-alphanumeric naming. Findings are discussed in relation to the phonological deficit theory of dyslexia.