Inter-Brain Basis Of Group Polarization In Risky Decision-Making

The research of risky decision-making is usually based on the individual,but in fact a large quantity of decisions are made by the group.Previous studies have found that for the same risky scenarios,decisions made in groups may be more extreme than decisions made by individuals,this phenomenon known as the group polarization effect.In different risk situations,when the initial position of group members is risky,the group shows more risk preference than the individual,which is called risky shift.When the initial position of group members is conservative,the risk preference of the group is more conservative than that of the individual,which is called cautious shift.The above group polarization effect has been widely demonstrated.However,the brain basis of group polarization has not been studied yet.This paper used near-infrared-based hyperscanning technology to investigate the group polarization and its direction under different risky scenarios,and the related brain-to-brain mechanism.Experiment 1(behavioral)examined the differences between groups relative to individual risk preferences under risk advantage/neutral/disadvantage scenarios.Experiment 2(f NIRS brain-imaging)simultaneously recorded the brain activity of 3 members of the group in the prefrontal lobe and left temporoparietal junction area,and examined the behavioral differences and neural characteristics of groups relative to individual risk preferences under risk advantage/disadvantage scenarios.Both experiments replicated the group polarization effects,that was,groups were more risk-seeking than individuals when risk was advantageous,and groups were more risk-averse than individuals when risk was disadvantageous.Further,the results of brain image showed that group decision-making elicited greater average inter-brain synchronization than individual decision-making in the right dorsolateral prefrontal cortex(r DLPFC)and left temporo-parietal junction(TPJ),but group decision making has lower average brain activation in the frontopolar area than individual decision making.Comparing the two risk scenarios,the increase of brain synchronization and the decrease of brain activation in the prefrontal cortex in the risk advantage scenarios were larger than those in the risk disadvantage scenarios.Meanwhile,the increase of group brain synchronization in the left temporoparietal junction area in both scenarios was related to group emotion and could predict group polarization.The study investigated the emergence of group polarization under risk-advantage/risk-disadvantage scenarios from behavioral and neural perspectives.Findings indicate that the process of group polarization may involve more inter-brain communication and fewer cognitive control.In addition,we suspect that emotion plays a role in the process of group polarization,for more group polarization with fewer negative emotions.This study is the first to explore the effect of group polarization from a neural perspective,which has practical guiding significance for studying the neural basis of group decision making.