Does discourse congruence influence spoken language comprehension before lexical association? Evidence from event-related potentials

The goal of this study was to examine how lexical association and discourse congruence affect the time course of processing incoming words in spoken discourse. In an event-related potential (ERP) norming study, we presented prime-target pairs in the absence of a sentence context to obtain a baseline measure of lexical priming. We observed a typical N400 effect when participants heard critical associated and unassociated target words in word pairs. In a subsequent experiment, we presented the same word pairs in spoken discourse contexts. Target words were always consistent with the local sentence context, but were congruent or not with the global discourse (e. g., Luckily Ben had picked up some salt and pepper/basil,'' preceded by a context in which Ben was preparing marinara sauce (congruent) or dealing with an icy walkway (incongruent). Event-related potential effects of global discourse congruence preceded those of local lexical association, suggesting an early influence of the global discourse representation on lexical processing, even in locally congruent contexts. Furthermore, effects of lexical association occurred earlier in the congruent than incongruent condition. These results differ from those that have been obtained in studies of reading, suggesting that the effects may be unique to spoken word recognition.