The Neural Mechanism Research Of Social Decision-Making Behavior Based On Multi-Brain Hyperscanning Technique

Social decision-making behavior refers to various types of decision-making behaviors based on social interaction.Due to the limitations of equipment,the neural mechanisms of social decision-making behavior in previous studies were conducted in the human-computer interaction or pseudo-personal interaction frame.The development of hyperscanning technique allows us to simultaneously collect and analyse information of multi-subjects’ brains,providing a way to examine the brain interaction and neural mechanisms among multi-subjects in a more realistic social environment.Social decision-making behavior mainly includes various decision-making behaviors based on cooperative and uncooperative frames.The cooperative behavior of social decision-making depends on both individual’s general willingness to(un)cooperate and general expectation of others.Meanwhile,due to the mismatch of information between competing parties,the pursuit of interests led to the occurrence of deceptive behavior and risky decision-making behavior in the uncooperative behavior.Functional near-infrared spectroscopy(fNIRS),a non-invasive neuroimaging tool which can be applied in open environment based on its advantages of portable,insensitive to head movement,excellent spatial and temporal resolution and high ecological validity.To fully understand the intra and inter-brain neural mechanisms of social decision-making behavior in social interaction situation,the present study employed a fNIRS hyperscanning technique to simultaneously measure pairs of participants’ brain activation by focused on two cooperative behaviors(cooperative decision-making behavior and cooperative expectation behavior)and two uncooperative behaviors(spontaneous deception and risky decision-making behavior).Moreover,the impact of individual differences such as gender effects and empathic traits on social decision-making behavior were also examined.Four experiments were set up in this research.Among them,Study #1 and #2 are cooperative behavior research while Study #3 and #4 are uncooperative behavior research.Study #1 used the multi-person prisoner’s dilemma game paradigm to examine the neural mechanisms of cooperative decision-making(group decision-making)behavior.Study #2 explored the neural mechanism of the expectation behavior by using an improved prisoner’s dilemma game.Meanwhile,two kinds of cooperation reward tasks were set up to investigate the impact of social environmental cues.Study #3 used a two-person gambling card-game to examine the neural mechanisms of spontaneous deception behavior.Study #4 explored the neural mechanism of the risky decision-making behavior by using the similar two-person gambling card-game.At the same time,we examine the relationship between environmental cues(i.e.,eye contact)and two uncooperative behaviors.The results are summarized as follows: 1.In the behavioral results of social decision-making behavior,the group decision-making/expectations lead to more collaborative results.The behavioral results of uncooperative behavior found that there is no difference between deception and honesty behavior.In contrast,in the outcome of risk decision-making,participants inclined to make risk aversion than risk seeking behavior.2.There are gender effects in social decision-making behavior.The study of two cooperative behaviors found that:(1)Male subjects have different intra-brain activations only in group decision-making.(2)By the modulation of social environmental cues,female subjects have different INSs in the two cooperative behaviors.(3)In the two cooperative behaviors,the INS of female subjects were higher than male subjects.(4)The study of uncooperative behavior found that only female subjects have INS in the temporo-parietal junction(TPJ).3.The outcomes of social decision-making behavior have different neural mechanisms.Both deceptive behavior and risk-seeking behavior lead to higher intra-brain activation and stronger INS.At the same time,the INS of the cooperative choice is higher than the defective choice in the group decision-making behavior.4.Social situational cues influence the cooperative behavior(group decision-making/expectation).Low-powered incentives yielded higher intra-brain activation,and high-powered incentives lead to stronger interpersonal synchronization(INS).However,the location of cortical activation and INS do not coincide.5.Individual differences have an impact on social decision-making behavior.The empathy and agreeableness traits can predict the outcome of cooperative behavior in female dyads.A general trend is that the INS of the cooperative choice is positively correlate with the agreeableness while the INS of the defective choice is negatively correlated with the empathy trait.In the study of uncooperative behavior,there was a significant positive correlation between the eye contact and the INS of deceptive behavior and the risk seeking behavior,especially in the female subjects.Based on the above experimental results,the following conclusions are drawn.First,the different neural mechanisms between cooperative and competitive behaviors indicate the central role of the theory of mind network and the mirror neuron system.Second,males and females invoke different neural networks in social decision-making.Males may primarily depend on non-social(executive control system)cognitive ability,while females may use both social and non-social cognitive abilities.Third,social decision-making behavior is shaped by the combination of internal and external factors,i.e.,social environmental cues and individual traits.In general,this study has carried out a higher ecological scientific research on social decision-making behavior by using the fNIRS-hyperscanning technique,enriching the study of social decision-making behavior,also contributed to the mechanisms exploration of the social brain in “Human Brain Project”.Meanwhile,the discovery of the underlying mechanisms offer a better guide to the diagnosis and treatment of individuals who lack social decision-making abilities(e.g.,autism).This study aims to make contribution to the understanding of human social decision-making behavior.