Dynamic inter-brain synchrony in real-life inter-personal cooperation: A functional near-infrared spectroscopy hyperscanning study

TLDR

Social interaction involves highly dynamic inter‑brain communication, yet prior hyperscanning studies have mainly examined static overall synchrony patterns, overlooking the temporal dynamics of interaction. In the present study, we propose a data‑driven approach based on sliding windows and k‑means clustering to capture the dynamic modulation of IBS patterns during interactive cooperation tasks. We used a portable fNIRS system to record hemodynamic responses from 20 dyads performing a creative design task and a 3D model‑building task. The sliding‑window, k‑means method revealed that naturalistic cooperation produced a sequence of dynamic IBS states, with the creative design task engaging more complex, region‑specific synchrony, demonstrating the approach’s ability to distill fine‑grained inter‑brain dynamics and advancing understanding of social neurocognition.

Abstract

How two brains communicate with each other during social interaction is highly dynamic and complex. Multi-person (i.e., hyperscanning) studies to date have focused on analyzing the entire time series of brain signals to reveal an overall pattern of inter-brain synchrony (IBS). However, this approach does not account for the dynamic nature of social interaction. In the present study, we propose a data-driven approach based on sliding windows and k-mean clustering to capture the dynamic modulation of IBS patterns during interactive cooperation tasks. We used a portable functional near-infrared spectroscopy (fNIRS) system to measure brain hemodynamic response between interacting partners (20 dyads) engaged in a creative design task and a 3D model building task. Results indicated that inter-personal communication during naturalistic cooperation generally presented with a series of dynamic IBS states along the tasks. Compared to the model building task, the creative design task appeared to involve more complex and active IBS between multiple regions in specific dynamic IBS states. In summary, the proposed approach stands as a promising tool to distill complex inter-brain dynamics associated with social interaction into a set of representative brain states with more fine-grained temporal resolution. This approach holds promise for advancing our current understanding of the dynamic nature of neurocognitive processes underlying social interaction.