Electrophysiological modulations of lexical prediction by conversation requirements
Language mediates most of our social life and yet, despite such social relevance and ubiquity, little is known about language processing during social interactions. To explore this issue, two experiments were designed to isolate two basic components of a conversation: 1) the interplay between language production and comprehension systems, and 2) the participation of a social partner. We explored how prediction processes in language comprehension are modulated by two basic components of a conversation. Participants were asked to perform a cross-modal priming paradigm in two blocks, one involving only comprehension trials and another in which trials requiring production and comprehension were intermixed. In the first experiment, participants were alone during the task and in the second experiment, participants believed they were performing the task jointly with an interactive partner. A critical electrophysiological signature of lexical prediction was observed, the N400 component, allowing to assess its modulation across conditions and experiments. when production was involved in the task, the effect of lexical predictability was enhanced at the early stages of language comprehension (anticipatory phase), irrespective of the social context. In contrast, language production reduced the effect of lexical predictability at later stages (integration phase), only when participants performed the task alone but not in the social context. These results support production based-models and reveal the importance of exploring language considering its interactive nature.