Group Identity and Social Preferences
通过实验室实验，发现当参与者与同组成员配对时，利他行为显著增加：慈善关注提高47%，嫉妒减少93%，更倾向于奖励好行为而少惩罚坏行为，并更可能选择社会福利最大化的行动。
We present a laboratory experiment that measures the effects of induced group identity on social preferences. We find that when participants are matched with an ingroup member, they show a 47 percent increase in charity concerns and a 93 percent decrease in envy. Likewise, participants are 19 percent more likely to reward an ingroup match for good behavior, but 13 percent less likely to punish an ingroup match for misbehavior. Furthermore, participants are significantly more likely to choose social-welfare-maximizing actions when matched with an ingroup member. All results are consistent with the hypothesis that participants are more altruistic toward an ingroup match.