Although Mismatch Negativity (MMN) effects indicating early, automatic lexical processing have been reported in the auditory language modality, so far these have not been reliably obtained in MMN studies of visual word recognition. The present study explores this discrepancy by investigating whether visual MMN (vMMN) effects can be obtained in written Chinese single-character word recognition. While participants were engaged in a non-linguistic distraction task, we measured Event-Related Potentials (ERPs) time-locked to perifoveally-presented real and pseudo- characters matched in overall visual-orthographic attributes. VMMN was defined as significant difference between the ERPs to characters presented as deviants or as standards in a context of non-characters. For the native Chinese readers, after sub-lexical structural detection from 120-160 ms, only real characters elicited vMMN at the interval of 170-210 ms, suggesting that lexical information in Chinese words is processed early and automatically. In a later window of 340-380 ms, both real and pseudo- characters yielded vMMNs. In a control group of non-Chinese participants, no evidence of vMMN was found for either real or pseudo-characters. Taken together, these results suggest that long-term memory representations for real characters may enable their early processing even in unattended conditions.
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