Uncovering the Neural Basis of Risk Preferences in Cooperative Dyads: A fNIRS Study

Individuals' risk preferences have been shown to influence their decision-making in various contexts. However, the neural mechanisms underlying the relationship between risk preference and decision-making in a social setting remain unclear. This study utilized functional near-infrared spectroscopy (fNIRS) to investigate the neural correlates of dyadic decision-making under risk and the modulating effect of individual risk preference. This study examined the impact of risk preference on group decision-making using a two-phase experimental design. Based on G-power software calculations, 168 right-handed participants (62 males, 106 females, mean age 21.26±1.70) were recruited initially. Participants first completed a single-player Sequential Risk Task to measure risk preference, followed by group classification into three groups: Risky&Risky, Risky&Safe, and Safe&Safe. Task performance and decision-making behavior were recorded. Functional Near-Infrared Spectroscopy (fNIRS) was employed to measure cortical activation in the prefrontal cortex, focusing on inter-brain synchrony and coupling directionality using wavelet coherence and Granger causality(GC) analyses. Data were preprocessed to remove noise, and statistical analyses included repeated measures ANOVAs, Support Vector Regression and multiple regression analyses. The study investigated dyadic risky decision-making among different paired groups, and the "Risky&Risky" group showed the highest risk-seeking behavior, with a significant main effect (F(2,81) = 7.438, P = 0.001). Inter-brain synchrony showed significance during outcome periods characterized by positive feedback, notably being higher within the "Risky&Risky" group. Granger causality analysis unveiled unique brain connectivity patterns, indicating that the GC values of "Risky&Safe" pairs increased during the diversion condition and decreased during the cooperation condition in comparison to other pairs, albeit without reaching statistical significance. Regression analysis indicated that OFC-mdlPFC GC values and personality traits were significant predictors of risk-taking, with the moderation of these effects by group membership (R²adjusted = 0.173 and 0.191). This study employed fNIRS hyperscanning to investigate how individual differences in risk preference impact decision-making in dyadic contexts. The results indicated that variations in connectivity and information transfer between the orbitofrontal and medial prefrontal cortices underlie the distinct risk-taking behaviors exhibited by dyadic pairs. These findings underscore the pivotal role of affective and cognitive control mechanisms and individual risk personality traits in cooperative decision-making under conditions of uncertainty.