Interpersonal Cooperation And Aggression Between In-group And Out-group: A FNIRS Research

Interpersonal cooperation,defined as interaction with others that increase shared performance,is one of the most important human social behaviors.Interpersonal conflict,which is another important social behavior,refers to people or groups competing for common goals.They are the most essential parts of social interaction and have important effects on human society.Significant differentiations displayed between In-group members and Out-group members during decision making of cooperation and aggression.Previous studies have identified that people tended to cooperate with intergroup members and it was critical for maximizing profit of their group.However,neural substrates are not clear about decision making of cooperation and aggression between in-group and out-group members.This study was conducted to exploring brain substrates of decision making about cooperation and aggression between in-group members and out-group members to 20 undergraduates using traditional Economic Game,Chicken Game,and functional near-infrared spectroscopy(fNIRS).The results revealed that:1、The average percentage of participants selected cooperation towards in-group members and out-group members was 57%and 35.16%,respectively.Paired-samples t-tests indicated that participants selected the cooperation strategy more with in-group members significantly than they did to out-group members.2、The reaction times of four conditions were not found to be statistically significant.3、Repeated measures analysis of variance revealed that the interaction between Group condition(In-group vs Out-group)and Decision making(Cooperation vs Aggression)was significant.The cortex area which significantly active was right dorsolateral prefrontal cortex,located at channel 5.Simple effect analysis revealed that compared with the out-group members,stronger brain activation was showed when participants chose aggression to their own team members;Compared with chose aggression,stronger brain activation was displayed when participants chose cooperation with out-group members.4、Significant differences for the main effect of Decision making(Cooperation vs Aggression)were showed.Right frontopolar area channel 11,displayed stronger activation when subjects chose cooperation than they chose aggression.5、Significant differences for the main effect of Group condition(In-group vs Out-group)were showed.Orbitofrontal area,channel 43,displayed stronger activation when made decision with in-group members than they interacted with out-group members.