Temporal Unfolding of Spelling-to-sound Mappings in Visual (Non)word Recognition.

Behavioral research has shown that inconsistency in spelling-to-sound mappings slows visual word recognition and word naming. However, the time course of this effect remains underexplored. To address this, we asked skilled adult readers to perform a 1-back repetition detection task that did not explicitly involve phonological coding, in which we manipulated lexicality (high-frequency words vs. pseudowords) and sublexical spelling-to-sound consistency (treated as a dichotomous-consistent vs. inconsistent-and continuous dimension), while recording their brain electrical activity. The ERP results showed that the adult brain distinguishes between real and nonexistent words within 119-172 msec after stimulus onset (early N170), likely reflecting initial, rapid access to a primitive visuo-orthographic representation. The consistency of spelling-to-sound mappings exerted an effect shortly after the lexicality effect (172-270 msec; late N170), which percolated to the 353- to 475-msec range but only for real words. This suggests that, in expert readers, orthographic and phonological codes become available automatically and nearly simultaneously within the first 200 msec of the recognition process. We conclude that the early coupling of orthographic and phonological information plays a core role in visual word recognition by mature readers. Our findings support "quasiparallel" processing rather than strict cognitive seriality in early visual word recognition.