An ERP study of category priming: evidence of early lexical semantic access

We investigated the effects of lexical semantic access on early components of high-density ERPs. Participants performed five blocks of a standard lexical decision (LD) task in which visually presented words were distinguished from nonwords (pseudowords) matched on word length. A second condition involved a lexical semantic (LS) version, in which the words (e.g., tiger) used in each block were selected from a single category (e.g., animals). ERP results indicated that (1) a main effect of lexicality occurred at 100 ms with P1 amplitude greater for words than for nonwords; (2) a task effect for both words and nonwords was also found in the P1 amplitude (larger for LS); (3) a lexicalityxtask interaction in the N1 amplitude indicated lexical semantic access by 168 ms; (4) semantic facilitation of response time to word-nonword judgment may be largely explained by P1 enhancement. Our findings of an early lexicality effect at 100 ms and of semantic access by 168 ms is in accordance with results of recent ERP and eye movement studies.