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Abstract:
This ERP study investigated the cognitive nature of the P1–N1 components during orthographic
processing. We used an implicit reading task with various types of stimuli involving different amounts
of sublexical or lexical orthographic processing (words, pseudohomophones, pseudowords, nonwords,
and symbols), and tested average and dyslexic readers. An orthographic regularity effect (pseudowords–
nonwords contrast) was observed in the average but not in the dyslexic group. This suggests
an early sensitivity to the dependencies among letters in word-forms that reflect orthographic structure,
while the dyslexic brain apparently fails to be appropriately sensitive to these complex features.
Moreover, in the adults the N1-response may already reflect lexical access: (i) the N1 was sensitive to
the familiar vs. less familiar orthographic sequence contrast; (ii) and early effects of the phonological
form (words-pseudohomophones contrast) were also found. Finally, the later N320 component was
attenuated in the dyslexics, suggesting suboptimal processing in later stages of phonological analysis.
