Tóth, D. , Varga, V. & Csépe, V.
Hungarian Academy of Sciences, Research Centre for Natural Sciences, Brain Imaging Centre
Reading acquisition alters the way the brain processes strings of familiar orthographic units (letters) compared to unknown visual stimuli. The left-lateralized N170 component of the event-related potential (ERP) is an early electrophysiological marker of this form of visual expertise.
In a follow-up experiment of an adult dyslexia study, we investigated whether the N170 effect emerges as early as first grade and it undergoes further development by third grade. We also tested the assumption that the development of the N170 effect is driven by grapheme-phoneme mapping. Fourty-one beginner readers were presented with pairs of pseudowords and pairs of Armenian character strings in a novel implicit reading paradigm where their task was to detect physically different (bold font) stimuli. To test the mapping hypothesis, the same pairs of stimuli were also presented in an audiovisual condition.
Our results demonstrated that even first grade students showed the N170 effect, similarly to third graders and previously tested adults. The parallel presentation of auditory stimuli enhanced the N170 effect, which suggests a role of orthographic-phonological mapping in the development of visual expertise for letter strings. Furthermore, the results elucidate the atypical response pattern of developmental dyslexic adults as revealed in our previous experiment.