Motivated by cycles of intergroup revenge in real-world conflicts, we experimentally test the hypothesis that humans practice group-based reciprocity: if someone harms or helps them, they harm or help other members of that person's group. Subjects played a trust game, then allocated money between other people. Senders whose partners returned more in the trust game gave more to that partner's group members. The effect was about half as large as the effect of direct reciprocity. Receivers' allocations to group members were not affected by their partners’ play in the trust game, suggesting that group reciprocity was only triggered by strong norm violations. We discuss the role of group reciprocity in conflict among early humans.
|Number of pages||6|
|Journal||Evolution and Human Behavior|
|Early online date||30 Aug 2018|
|Publication status||Published - Jan 2019|
- Upstream reciprocity
- Group identity
- Intergroup conflict