Aial Sobeh - First Place
Advisor - Prof. Simone Shamay-Tsoory
Department of Psychology

Research indicates that within ideologically homogenous groups, members tend to adopt more extreme views after group discussions, a phenomenon known as the echo chamber effect. According to previous research, discussions within homogenous groups can lead to polarization because members primarily encounter information that supports their existing positions, thereby fostering a confirmatory rather than critical group mindset and driving over-confidence. Accordingly, we propose that neural mechanisms that support a flexible group mindset may mitigate the polarizing effect of echo chambers. Specifically, we hypothesized that inter-brain synchrony between group members in the executive control network (ECN), a brain network supporting effortful and flexible thinking, can moderate the effect of homogeneity on polarization. To test our hypothesis, we designed a functional near-infrared spectroscopy (fNIRS) hyperscanning paradigm in which groups of four individuals (n groups = 50) engaged in a moral judgment task, while their brain activity is scanned. The task involved presenting participants with a series of moral dilemmas and asking them to rate the morality of controversial actions described in those dilemmas. Participants rated each dilemma two times: first independently in private before any social interaction, and then again a9er a group discussion. This experimental design allowed us to derive two behavioral measures: a measure of group homogeneity based on how homogeneous initial ratings were, and a measure of polarization based on how much participants’ final private ratings (post group discussion) were more extreme compared to initial ratings (pre group discussion). Our results show that deliberations within homogeneous, compared to heterogeneous groups, led to increased polarization. Critically, we also found that higher interbrain synchrony between group members diminishes the effect of homogeneity on polarization. Our research illuminates the interpersonal mechanisms that takes place within echo chambers and suggests how to mitigate their polarizing effect.