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Saturday, July 2, 2022

Shadow of conflict: How past conflict influences group cooperation and the use of punishment

J. Grossa, C. K. W. DeDreua, & L. Reddmann
Organizational Behavior and Human Decision Processes
Volume 171, July 2022, 104152


Intergroup conflict profoundly affects the welfare of groups and can deteriorate intergroup relations long after the conflict is over. Here, we experimentally investigate how the experience of an intergroup conflict influences the ability of groups to establish cooperation after conflict. We induced conflict by using a repeated attacker-defender game in which groups of four are divided into two ‘attackers’ that can invest resources to take away resources from the other two participants in the role of ‘defenders.’ After the conflict, groups engaged in a repeated public goods game with peer-punishment, in which group members could invest resources to benefit the group and punish other group members for their decisions. Previous conflict did not significantly reduce group cooperation compared to a control treatment in which groups did not experience the intergroup conflict. However, when having experienced an intergroup conflict, individuals punished free-riding during the repeated public goods game less harshly and did not react to punishment by previous attackers, ultimately reducing group welfare. This result reveals an important boundary condition for peer punishment institutions. Peer punishment is less able to efficiently promote cooperation amid a ‘shadow of conflict.’ In a third treatment, we tested whether such ‘maladaptive’ punishment patterns induced by previous conflict can be mitigated by hiding the group members’ conflict roles during the subsequent public goods provision game. We find more cooperation when individuals could not identify each other as (previous) attackers and defenders and maladaptive punishment patterns disappeared. Results suggest that intergroup conflict undermines past perpetrators’ legitimacy to enforce cooperation norms. More generally, results reveal that past conflict can reduce the effectiveness of institutions for managing the commons.


• Intergroup conflict reduces the effectiveness of peer punishment to promote cooperation.

• Previous attackers lose their legitimacy to enforce cooperation norms.

• Hiding previous conflict roles allows to re-establish group cooperation.

From the Discussion

Across all treatments, we observed that groups with a shadow of conflict earned progressively less and, hence, benefitted less from the cooperation opportunities they had after the conflict episode compared to groups without a previous intergroup conflict (control treatment) and groups in which previous conflict roles were hidden (reset treatment). By analyzing the patterns of punishment, we found that groups that experienced a shadow of conflict did not punish free-riders as harshly compared to the other treatments. Further, punishment by past attackers was less effective in inducing subsequent cooperation, suggesting that attackers lose their legitimacy to enforce norms of cooperation when their past role in the conflict is identifiable (see also Baldassarri and Grossman, 2011, Faillo et al., 2013, Gross et al., 2016 for related findings on the role of legitimacy for the effectiveness of punishment in non-conflict settings). Even previous attackers did not significantly change their subsequent cooperation when having received punishment by their fellow, previous attacker. Hiding previous group affiliations, instead, made punishment by previous attackers as effective in promoting cooperation as in the control treatment.

These results reveal an important boundary condition for peer punishment institutions. While many experiments have shown that peer punishment can stabilize cooperation in groups (Fehr and G├Ąchter, 2000, Masclet et al., 2003, Yamagishi, 1986), other research also showed that peer punishment can be misused or underused and is not always aimed at free-riders. In such cases, the ability to punish group members can have detrimental consequences for cooperation and group earnings (Abbink et al., 2017, Engelmann and Nikiforakis, 2015, Herrmann et al., 2008, Nikiforakis, 2008).