Electrophysiological evidence for reversed lexical repetition effects in language processing

Effects of word repetition are extremely robust, but can these effects be modulated by discourse context? We examined this in an ERP experiment that tested coreferential processing (when two expressions refer to the same person) with repeated names. ERPs were measured to repeated names and pronoun controls in two conditions: (1) In the prominent condition the repeated name or pronoun coreferred with the subject of the preceding sentence and was therefore prominent in the preceding discourse (e.g., "John went to the store after John/he...''); (2) in the nonprominent condition the repeated name or pronoun coreferred with a name that was embedded in a conjoined noun phrase, and was therefore nonprominent (e.g., "John and Mary went to the store after John/he...''). Relative to the prominent condition, the nonprominent condition always contained two extra words (e.g., "and Mary''), and the repetition lag was therefore smaller in the prominent condition. Typically, effects of repetition are larger with smaller lags. Nevertheless, the amplitude of the N400 was reduced to a coreferentially repeated name when the antecedent was nonprominent as compared to when it was prominent. No such difference was observed for the pronoun controls. Because the N400 effect reflects difficulties in lexical integration, this shows that the difficulty of achieving coreference with a name increased with the prominence of the referent. This finding is the reverse of repetition lag effects on N400 previously found with word lists, and shows that language context can override general memory mechanisms.