Ingroup Favoritism In Cooperation In The One-shot Game

Previous research has found that individuals are more willing to pay for the benefit of ingroup members than outgroup members in the repeated game and show ingroup favoritism in cooperation.Social identity theory and bounded generalized reciprocity theory explain the ingroup favoritism in cooperation in the repeated game from the perspectives of self-concept and reputation concern.Social identity theory holds that part of individual’s self-concept originates from ingroup.Individuals expect ingroup to perform better than the outgroup through social comparison,thereby gaining a positive self-concept,and thus show ingroup favoritism in cooperation.Bounded generalized reciprocity theory holds that the individuals pay more attention to their reputation in the ingroup,which leads to the ingroup favoritism in cooperation.Recently,some researchers have pointed out that the above two theories are probably not applicable to explain the ingroup favoritism in cooperation in the one-shot game,because it is more difficult for individuals to form a stable self-concept from the group they belong to in the one-shot game than in the repeated game,and they do not need to pay attention to their reputation in the ingroup,but this speculation has not been fully experimentally proven.Thus,at present,the mechanism of the ingroup favoritism in cooperation in the one-shot game is unclear.Social projection theory provides a new perspective for solving the above problems.Previous research has found that individuals project more to ingroup than outgroup,and the social projection theory proposes that the higher the level of social projection,the greater the possibility of cooperation.Therefore,it is likely that individuals’ higher level of social projection to ingroup could lead to ingroup favoritism in cooperation.The purpose of this study is to systematically explore the ingroup favoritism in cooperation in the one-shot game and its influencing factors and potential mechanisms from the perspective of social projection.This study consists of three parts.The first part contains two experiments,which are aimed at examining whether there was ingroup favoritism in cooperation in the one-shot game,and if so,whether social projection theory can explain it better than the aforementioned social identity theory and bounded generalized reciprocity theory.Experiment 1 adopted painting preference task to create groups and examines whether there was ingroup favoritism in cooperation in the one-shot prisoner’s dilemma game.Experiment 2 manipulated the index of cooperation of the earnings matrix in the oneshot prisoner’s dilemma game,social projection theory predicts that the level of the index of cooperation would influence the degree of ingroup favoritism in cooperation,but social identity theory and bounded generalized reciprocity theory predicts that the level of the index of cooperation would not influence the degree of ingroup favoritism in cooperation.In response to these two different predictions,experiment 2 explored which theory’s prediction could be better confirmed,and whether social projection theory was better than the other two to explain the phenomenon of ingroup favoritism in cooperation in the one-shot game.The second part contains three experiments designed to further explore the role of social projection in ingroup favoritism in cooperation in the one-shot game on the basis of the first part.Both experiments 3 and 4 adopted dots estimation task to create groups,and respectively used the prisoner’s dilemma game and the public-goods game to measure the level of cooperation.Based on the speculations of bounded generalized reciprocity theory and social projection theory,the individual’s reputation concern and social projection for ingroup and outgroup were used as potential mediating variables to detect whether they mediated the influence of group on cooperation and which one had a greater mediating effect,to explore whether social projection theory is rational for explaining the ingroup favoritism in cooperation in the one-shot game.Experiment 5 directly manipulated the individual’s level of social projection to make individuals hold the same or different level of social projection for the ingroup and outgroup when completing the prisoner’s dilemma game,to investigate whether the ingroup favoritism in cooperation would disappear when participants held the same level of social projection for the ingroup and outgroup,trying to further prove the role of social projection.In addition,previous research has shown that individual’s level of perspective taking influences the willingness of individuals to project on others in specific situations.If social projection is an important reason for the ingroup favoritism in cooperation,then the level of perspective taking should influence the degree of ingroup favoritism in cooperation.In particular,when the level of perspective taking is low,individuals are less likely to project on ingroup and outgroup,which resulting in weakened ingroup favoritism in cooperation.Based on this,the third part introduces perspective taking as a moderating variable,and aims to explore whether it moderated the effect of group on cooperation through social projection in one-shot game.The third part consists of four experiments: experiments 6 and 7 used laboratory-created groups,experiments 8 and 9 used natural groups,and experiments 6 and 8 measured the individual’s level of perspective taking,and experiments 7 and 9 manipulated the individual’s level of perspective taking.This paper systematically examined the influence of perspective taking on the degree of ingroup favoritism in cooperation in one-shot prisoner’s dilemma game.In this study,the difference in cooperation between ingroup and outgroup was used as an indicator of the degree of ingroup favoritism in cooperation.The results are as follows: first,participants showed ingroup favoritism in cooperation in the one-shot prisoner’s dilemma game(experiment 1).Second,the level of the index of cooperation in the one-shot prisoner’s dilemma game influenced the degree of ingroup favoritism in cooperation(experiment 2): under the condition of high index of cooperation,the phenomenon of ingroup favoritism in cooperation existed,but under the condition of low index of cooperation,the phenomenon of ingroup favoritism in cooperation disappeared,confirming the prediction of the social projection theory.Third,in oneshot prisoner’s dilemma game(experiment 3)and one-shot public-goods game(experiment 4),group influenced cooperation through social projection rather than reputation concern: compared to outgroup,participants projected more to ingroup,and thus cooperated more to ingroup.When the level of social projection was manipulated to make individuals have the same level of social projection to ingroup and outgroup,the phenomenon of the ingroup favoritism in cooperation disappeared;when the level of social projection was manipulated to make individuals project more to ingroup than outgroup,the phenomenon of the ingroup favoritism in cooperation still existed(experiment 5).Fourth,in one-shot prisoner’s dilemma game,perspective taking moderated the effect of group on cooperation through social projection.Further analysis found that perspective taking influenced the degree of ingroup favoritism in cooperation through the difference in social projection between ingroup and outgroup:(1)In the laboratory-created group(experiment 6)and the natural group(experiment 8),compared with individuals with inherently low level of perspective taking,individuals with inherently high level of perspective taking showed greater differences in their degree of social projection between ingroup and outgroup and then showed higher degree of ingroup favoritism in cooperation.(2)In the laboratory-created group(experiment 7)and the natural group(experiment 9),individuals’ differences in the degree of social projection between ingroup and outgroup became larger after the experimental manipulation to enhance the level of perspective taking,showing a greater degree of ingroup favoritism in cooperation.In summary,the results of this study show that,compared to bounded generalized reciprocity theory and social identity theory,social projection theory better explains the phenomenon of ingroup favoritism in cooperation in one-shot game.Although betrayal is a dominant strategy in one-shot game,due to individuals’ higher level of social projection to ingroup,cooperation is more likely to replace betrayal as the dominant strategy when opponents are from ingroup.The level of individual’s social projection to ingroup and outgroup is influenced by perspective taking,the higher the level of perspective taking,the greater the difference in social projection between ingroup and outgroup,and the greater the degree of ingroup favoritism in cooperation.This study refines,improves and deepens research in related fields.It has certain reference and guidance significance on how to weaken the dilemma of cooperation and encourage individuals to choose cooperation to maximize the collective benefits.