Supporting again the N400 ERP inhibition hypothesis and seeing that being alone vs. with a friend modulates the (self) P2, rather than the social N400

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Sujata Sinha¹ (sujata.sinha@mail.mcgill.ca), Ashley Chau-Morris¹, Milena Kostova², J. Bruno Debruille¹; ¹McGill University, ²University of Paris 8

The presence of a (previously unknown) confederate can induce an increase of the amplitude of the N400 event-related brain potential (ERP). This so-called social N400 has recently been proposed to index the sidelining of the privileged information that the stimulus may activate in the participants so that they can focus on the ground that is common with an unknown person. Confirming this social N400 sidelining interpretation, we observed no social N400s here, where the confederate was a friend of the participants and thus, a person with whom common grounds had already been built and with whom it may be detrimental to set aside privilege information that could enrich the relationship. Unexpectedly, P2 ERPs were smaller, particularly at the central electrode-site. These smaller P2s were tentatively related to a modulation of the binding of the stimulus representations with the representations of the self when participants were in the presence of a well-known friend who was perceiving the stimuli at the same time as they were. Noteworthy, short stories ending predictably, unpredictably, or equivocally were used as stimuli. Interestingly, results fit the N400 inhibition hypothesis, which sees N400 processes as preventing some information from entering working memory and thus, from enlarging the amplitudes of the late positive potentials (LPPs). Indeed, participants who had larger N400s to equivocal than to predictable endings did not have larger LPPs for these endings than for the predictable ones whereas such larger LPPs were observed in participants who had smaller N400s for equivocal than for predictable endings.

Topic Area: LANGUAGE: Semantic