Interbrain visual entrainment induces increases in dyadic cooperation

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

Ivo Leiva^1,3 (ivo.leiva@ciae.uchile.cl), Eugenio Rodriguez³, Paulo Barraza^1,2; ¹Institute for Advanced Studies in Education (IE), University of Chile, ²Center for Advanced Research in Education (CIAE), University of Chile, ³Laboratory of Basic and Applied Neurodynamics, School of Psychology, Pontifical Catholic University of Chile

Most hyperscanning studies show that individuals synchronize their brain activities when they engage in social interactions, posing such inter-brain synchrony as a mechanism supporting social activity. However, as social interactions afford similar stimulation for the involved subjects, it has proven difficult to test whether the observed synchrony corresponds to a genuine neural mechanism or is rather spurious due to similar stimulation. To address this problem, we implemented for the first time an interbrain sensory entrainment paradigm, which allowed us to manipulate brain synchrony between interacting partners in terms of frequency and phase. We added flickering stimuli to a classical cue-target cooperation task to visually entrain twelve same-sex dyads in four blocks. At each block, participants were entrained at 16 Hz or 40 Hz, and either synchronously or asynchronously (delayed flickering onset) between them. Sixteen same-sex control dyads performed the same task without any flickering. We found that: i) overall cooperation rates were significantly higher for the entrained group compared to control group; ii) cooperation rates under 16 Hz synchronous entrainment was significantly higher than under 16 Hz delayed-onset and iii) 40 Hz entrainment protocols had no effect over cooperation rates. Additional permutation tests against shuffled pseudo-dyads further confirm the observed differences. Using fine-controlled, rhythmic sensory stimulation, we demonstrate that affecting the degree of neural synchrony between interacting partners yields clear changes in their interpersonal behavior, thus supporting the notion that inter-brain synchrony is not a spurious phenomenon and, conversely, is a genuine neural mechanism supporting social interactions.

Topic Area: EMOTION & SOCIAL: Other