Effects Of Acute Stress On Interpersonal Cooperation And Competition

In daily life,individuals often face various internal or external stimuli,and when they perceive an imbalance between their coping skills and objective requirements,there will be psychological and physiological stress responses.In the early days,“fight or flight” has been considered as a common stress response between men and women until “tend and befriend” provides a new perspective for the study of female stress response.Previous studies have shown that acute psychological stress can increase prosocial behavior and lead to “tend and befriend”,but there is little research about direct cooperative behavior under stress.For competitive behavior,there is no consistent results for “fight or flight”.Besides,current stress research is more concentrated in men rather than women,and little is known about the neural mechanism of acute stress response.Also,the ecological validity of current interpersonal cooperation and competition experiments need to be improved.Based on fNIRS hyperscanning technology,present study discussed the problem above and explored effects of acute stress on interpersonal cooperation and competition.Female college students were selected as subjects in current study.Montreal Imaging Stress Task(MIST)was used to induce acute stress(stress group)or nonacute stress(control group).Then subjects were required to complete the cooperative task and the competitive task,and in the same time,the brain activities of each pair of subjects were simultaneously recorded.In cooperative task,the interaction effect of group and time course of cooperation rate was founded.The cooperation rate in stress group was significantly improved.Single brain activation data showed that there was a main effect of time course of Beta.INS data showed that control group and stress group had significantly enhanced INS in different channels in PFC and rTPJ,and there was no significant difference between groups.In addition,the interaction effect of group and time course of INS in the right superior marginal cortex was founded.Also,the INS of right margin of stress group was positively correlated with cooperation rate,but there was no such positive correlation in control group.And it was found that only the stress group had a positive correlation between INS and cooperation rate in late task.There was a positive correlation between late INS and early cooperation rate.The results of cooperative task showed that INS is related to cooperative behavior under acute stress,and both of them had significantly enhanced with time course.Early cooperative behavior may predict late INS.Late brain activation is greater than early brain activation.In competitive task,response time in stress group was significantly smaller meant the competition performance of stress group was significantly stronger than control group.Single brain activation data showed that there was no single brain activation channel in control group,and lots of single brain activation channels in stress group.Include frontopolar area,dorsolateral prefrontal cortex,right superior temporal cortex,right middle temporal cortex,right superior marginal cortex,right posterior central cortex and right inferior parietal cortex.The activation in the frontopolar area of stress group was significantly different from control group.Neither control group nor stress group had INS increase.The results of competitive task showed that competition under acute stress was enhanced,and there was significant brain activation in the frontopolar area compared with control group.As for INS,there was no INS increase in both control group and stress group.By comparing the cooperative task and competitive task in this study,from the perspective of behavior data,the time course had an effect on cooperation rate in cooperative task rather than competitive task.From the perspective of single brain activation,the subjects showed single brain activation only in competitive tasks under stress.From the perspective of INS,significant increase of INS occurred in both control group and the stress group in cooperative task and there was a significant positive correlation between INS and cooperation rate in stress group,but there was no increase of INS in competitive task,both in control group and stress group.In this study,the fNIRS hyperscanning technology was used to reveal the relationship between cooperation behavior and INS under acute stress and the effect of time course on cooperation,brain activation and inter-brain coherence.It reveals the tendency of competition to “fight” for “fight or flight” and a significant increase in brain activation under acute stress.Also,behavioral data,single-brain activation data and INS were compared between cooperative task and competitive task.