Implicit and Explicit Mechanisms of Word Learning in a Narrative Context: An Event-related Potential Study

摘要

The vast majority of word meanings are learned simply bynextracting them from context rather than by rote memorizationnor explicit instruction. Although this skill is remarkable, littlenis known about the brain mechanisms involved. In the presentnstudy, ERPs were recorded as participants read stories in whichnpseudowords were presented multiple times, embedded innconsistent, meaningful contexts (referred to as meaning condition,nM+) or inconsistent, meaningless contexts (M−). Wordnlearning was then assessed implicitly using a lexical decisionntask and explicitly through recall and recognition tasks. Overall,nduring story reading, M− words elicited a larger N400 thannM+ words, suggesting that participants were better able tonsemantically integrate M+ words than M− words throughoutnthe story. In addition, M+ words whose meanings were subsequentlyncorrectly recognized and recalled elicited a more positivenERP in a later time window compared with M+ wordsnwhose meanings were incorrectly remembered, consistent withnthe idea that the late positive component is an index of encodingnprocesses. In the lexical decision task, no behavioral or electrophysiologicalnevidence for implicit priming was found fornM+ words. In contrast, during the explicit recognition task,nM+ words showed a robust N400 effect. The N400 effect wasndependent upon recognition performance, such that only correctlynrecognized M+ words elicited an N400. This pattern ofnresults provides evidence that the explicit representations ofnword meanings can develop rapidly, whereas implicit representationsnmay require more extensive exposure or more time tonemerge. ■