Interpersonal Neural Mechanisms Underlying Shift Of Risk Preference During Observing Others’ Gambling

Attitudes towards risk lead people to making various decision.Besides,others’ attitude also modulate individuals’ risky decision.This phenomenon is social influence which is a tendency to conform to others’ beliefs or attitudes when the individual’s belief conflicts with others’.Previous studies usually focus on the individuals under social influence while ignoring individuals who are behind the social influence.The dynamic characteristic of social influence and the underlying interpersonal neural mechanisms remain poorly understood.In this study,we investigated how the social influence changed the individuals’ risk preference during observing others’ gambling.We recruited 4 participants to be as observee and 60 participants to be as observer.The risk preference of participants was either risk-seeking or risk-averse.We manipulated the congruence of risk preference between observee and observer,resulting in two groups in the current study(i.e.,observee’s risk preference was congruent/incongruent with observer’s).The observer was asked to complete three types of task,namely solo task,predict task and observe task,while the observee was only asked to complete solo task repeatedly.The observer was asked to predict the observee’s choice during predict task and observe the observee’s choice during observe task.The risk preference was estimated individuals’ choice during solo task with computational model.The shift of risk preference was the difference of risk preference between before and after observe task.We calculated the prediction accuracy of observer during three blocks of predict task.Because theta band oscillation represents the prediction error signal and beta band oscillation represents reward in task,we calculated the brain-to-brain coupling between observee and observer in the two bands with Circular Correlation Coefficient(CCorr)when they were doing observe task.We calculated the time-lagged CCorr and the CCorr of pseudo dyads.Several fundamental observations were made.First,the shift of observers’ risk preference was larger in the incongruent group than in the congruent group,suggesting social influence could alter the individuals’ risk preference.Second,the prediction accuracy showed significant difference between groups in the first round,while the accuracy didn’t differ between groups in the last two rounds.Third,in the theta band,CCorr in the congruent group was significantly higher than CCorr in the incongruent group,which were between the left temporal-parietal and frontal-central areas of observer and the parietal-occipital area of observee.CCorr in this band was associated with the shift of observer’s risk preference,suggesting that brain-to-brain coupling in this band could predict the change of risk preference and was the interpersonal neural marker of prediction error signal.Fourth,in the beta band,CCorr in the incongruent group was significantly higher than CCorr in the congruent group,which were between the right temporal-parietal area of observer and the frontalparietal area of observee.CCorr in this band was associated with the distance between observee’s and observer’s risk preference,suggesting that brain-to-brain coupling in this band might represent the social reward due to having similar risk preference to others’.Fifth,significant coupling was found at lags of-100,0 and 100 ms in the theta band,while significant coupling was only found at lags of 0 ms in the beta band.This result demonstrated that the brain-to-brain coupling was due to the real-time interaction between observee and observer.Sixth,there was a congruence × group(real,pseudo group)interaction in both bands,suggesting that coupling was special to real interacting dyads.This study demonstrated that brain-to-brain coupling in the theta and beta band could be an interpersonal neural marker representing how social influence change individuals’ risk preference.And brain-to-brain coupling could be a potential mechanism underlying social influence.Furthermore,the current study suggested this coupling might play a key role in various activities involving social influence.