Hyperscanning During Conversation
EEG hyperscanning refers to recording electroencephalographic (EEG) data from multiple people simultaneously. Many hyperscanning studies seek to record neuroimaging data under more naturalistic conditions than conventional lab-based studies — relying on unpredictable, participant-generated stimuli rather than standardized, pre-determined stimuli. The majority of this research using EEG has focused on neural oscillatory activity that is quantified over hundreds of milliseconds or more. This contrasts with event-related potential (ERP) research, in which analysis focuses on transient responses, often only tens of milliseconds in duration. Deriving ERPs requires precise time-locking between stimuli and EEG recordings, and thus typically relies on pre-set stimuli that are presented to participants by a system that controls stimulus timing and synchronization with an EEG system. EEG hyperscanning methods typically use separate EEG amplifiers for each participant, increasing cost and complexity — including challenges in synchronizing data between systems.
In a recent paper, we describe a method that allows for simultaneous acquisition of EEG data from a pair of participants engaged in conversation, using a single EEG system with simultaneous audio data collection that is synchronized with the EEG recording. This allows for the post-hoc insertion of trigger codes so that it is possible to analyze ERPs time-locked to specific events. In the paper we also demonstrated methods for deriving ERPs elicited by another person’s spontaneous speech, using this setup.
We have used this approach to demonstrate that we can obtain the classic N400 ERP to spoken words during a conversation, and further that — as in previous lab-based studies — the N400 is modulated by the frequency with which words occur in the language.
This project was funded by NSERC.