Brain-to-Brain Synchronization When Sharing Positive Emotions Based on Memories: An fNIRS Hyperscanning Study

Interpersonal neural synchrony (i.e., brain-to-brain synchronization, BBS) during collaborative tasks is an emerging area of research.The aim was to investigate whether sharing positive emotions through storytelling among colleagues enhances neural synchrony levels measured by functional near-infrared spectroscopy (fNIRS).

Fifteen pairs of co-workers (age: 39.5 ± 12.2 years, range: 21-60 years) from different professional backgrounds participated in the study. Each pair participated in three measurement sessions, with simultaneous fNIRS recording (left/right temporal-parietal and prefrontal cortex) during three different tasks: puzzle completion, sharing positive memories, and a verbal reasoning task. Participants were divided into three groups based on the frequency of practicing positive memory sharing between sessions. BBS was assessed using wavelet transform coherence (frequency range: 0.015-0.15 Hz). Linear mixed model analysis with bootstrapping was employed to examine the effects of "session" and "group" on BBS, with "pair ID" treated as a random effect.

Significant increases in [O₂Hb] BBS in the left temporal-parietal region were observed between session 1 and session 3 (0.004-0.02) and between session 1 and session 2 (0.01-0.06). Groups practicing more frequently showed higher BBS levels (0.005-0.6 in [O₂Hb]; 0.009-0.06 in [tHb]).

In our fNIRS hyperscanning study, we found that continuous sharing of personal experiences with positive emotions significantly enhances neural synchrony among co-workers, particularly in the left temporal-parietal region. More frequent practice led to higher BBS levels, suggesting the importance of regular collaborative activities, such as team-building exercises, in workplace settings. While bootstrapping was applied to improve statistical robustness, the small sample size remains a limitation, and further studies with larger sample size are needed to validate these findings.