We report an experiment in which the Intergroup Prisoner's Dilemma (IPD) game was contrasted with a structurally identical (single-group) Prisoner's Dilemma (PD). The games were played repeatedly for 40 rounds. We found that subjects were initially more likely to cooperate in the IPD game than in the PD game. However, cooperation rates decreased as the game progressed and, as a result, the differences between the two games disappeared. This pattern is consistent with the hypothesis that subjects learn the structure of the game and adapt their behavior accordingly. Computer simulations based on a simple learning model by Roth and Erev (Learning in extensive-form games: Experimental data and simple dynamic models in the intermediate term, Games and Economic Behavior 8, 164-212, 1995) support this interpretation.
Bibliographical noteFunding Information:
This researchw as supportedb y a grantf rom the Israel FoundationT rustees (94-96) to Gary Bornsteina, nd by a grantf rom the Israel ScienceF oundation (94-97)t o Gary Bornsteina ndEyal Winter.W e wish to thankY ael Zick, Alona Harnes,S hiraPnueli, and Naomi Shwimerf or their help in data collectiona nd dataa nalysis.
- Intergroup Prisoner's Dilemma game
- Intergroup conflict
- Repeated team-games