This paper studies how competition between groups affects cooperation. In the control condition, pairs of subjects play an indefinitely repeated Prisoner's Dilemma game without external competition. In the treatment, two pairs compete against each other. No monetary rewards are tied to winning,...

We conduct a laboratory experiment to compare the fairness and intensity of round-robin tournaments with three symmetric players, a single prize, and two alternative match formats. Matches are either organized as lottery contests or all-pay auctions. Whereas we confirm the theoretical prediction...