Context Matters: Hyperscanning the N400 Lexical Frequency Effect During Conversation and Passive Listening

Abstract

Conventional event-related potential (ERP) studies of lexical processing typically involve individuals comprehending isolated words or sentences. However, much of language processing occurs in conversation with others. Here, we used EEG hyperscanning to record ERPs from pairs of acquaintances either engaged in conversation, or passively viewing a conversation. Our primary goals were to replicate the established N400 frequency effect (a greater amplitude negativity between ~300–600 ms for low-frequency words), and compare this effect during conversation versus passive viewing, which more closely resembles traditional ERP paradigms. Pairs of participants engaged in a scripted conversation while EEG was simultaneously recorded from both interlocutors. Separately, pairs of individuals watched a recording of the same scripted conversation to control for the effect of social interaction. Target words of high and low lexical frequency were embedded in the dialogues, and the onsets of these words were identified post hoc from audio synchronized with the EEG data. Both groups exhibited a significantly greater N400 response to low-frequency words compared to high-frequency words, replicating previous findings. However, the N400 frequency effect was larger in the passive viewing group than in the conversation group across midline central-parietal channels. This attenuation in the conversation condition may reflect differences in lexical processing during active social interaction compared to passive comprehension. These findings demonstrate that ERP experiments can be conducted using natural conversational stimuli, opening new opportunities to study real-time language processing in interactive social contexts.