Slide Slam I6
Detecting the N400 ERP using EEG hyperscanning during conversation in both conversation participants and observers
Caitriona (Katie) Douglas1, Aaron Newman1; 1Dalhousie University
EEG hyperscanning, which refers to recording simultaneous EEG data from multiple people, are becoming more popular in language cognition research. Studies have mainly focused on neuro-oscillatory dynamics as it is difficult to examine unpredictable occurrences in a highly time-locked manner as necessitated by event-related potential (ERP) studies. We developed EEG hyperscanning methods to detect ERPs in response to words people hear during a conversation. Specifically, we examined if the N400 response differed between hearing low and high lexical frequency words. Twenty pairs of participants had a scripted conversation together while EEG hyperscanning occurred. A key feature of this task is that participants are asked to self-generate the linguistic stimuli themselves by reading lines to each other of a scripted dialogue. Each participants' script contained only their own lines that they said during the scripted dialogue and displayed only simple cues of when it was their partners' turn to speak. Therefore, each participant served as their partners' stimuli delivery system as we only examined the participants responses when they were acting as the listener during the conversational exchanged. A control group of twenty other pairs of participants watched a recording of the same conversations while undergoing EEG hyperscanning. We then transcribed the recorded dialogues to mark the onset times of each word of interest to which ERPs were obtained. There was a significantly greater N400 response to low frequency words in comparison to high frequency words in both groups, replicating previous findings. These results demonstrate that the N400 ERP experiments can be conducted using stimuli generated by experimental participants engaged in conversation as N400 characteristics and effects were comparable both when participants self-generated the stimuli themselves by having a scripted conversation and when participants watched video recordings of the scripted conversation. This opens up new opportunities for more naturalistic ERP studies of language.