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In the two-person sequential best shot game, first player 1 contributes to a public good and then player 2 is informed about this choice before contributing. The payoff from the public good is the same for both players and depends only on the maximal contribution. Efficient voluntary cooperation in the repeated best shot game therefore requires that only one player should contribute in a given round. To provide better chances for such cooperation, we enrich the sequential best shot base game by a third stage allowing the party with the lower contribution to transfer some of its periodic gain to the other party. Participants easily establish cooperation in the finitely repeated game. When cooperation evolves, it mostly takes the form of "labor division," with one participant constantly contributing and the other constantly compensating. However, in a treatment in which compensation is not possible, (more or less symmetric) alternating occurs frequently and turns out to be almost as efficient as labor division.

Two pairs of two participants each interact repeatedly in two structurally Independent but informationally linked Prisoner’s Dilemma games. Neither pair receives Feedback about past choices by their own partner but is fully informed about the choices by the other pair. Considering this as a four-person infinite horizon game allows for Folk-Theorem-like voluntary cooperation. We ask whether monitoring and indirect punishment with the help of others are comparable to direct monitoring and punishment in establishing and maintaining voluntary cooperation. The treatment effects we find are rather weak. Others’ monitoring of own activities is only an insufficient substitute for direct observability.

This paper tests two basic assumptions underlying court made or statutory provisions prohibiting predatory pricing. Such prohibitions are usually based on the economic grounds that monopolistic pricing is likely to occur in the long run, causing harm to competition and consumers. The first assumption under scrutiny is that customers will accept monopolistic prices during the subsequent phase of recoupment, even though they have become accustomed to low prices during the price war. The second assumption is that no competitor will (re-)enter the market in this subsequent phase. Our two experiments indicate that both assumptions are not backed up by actual decision making both of consumers and of competitors. Moreover, we find that consumers use their market power in order to maintain long-run competition.

Unlike previous attempts to implement cooperation in a prisoners' dilemma game with an infinite horizon in the laboratory, we focus on extended prisoners' dilemma games in which a second (pure strategy) equilibrium allows for voluntary cooperation in all but the last round. Our four main experimental treatments distinguish long versus short horizon and strict versus non-strict additional equilibrium compared to the control treatment, a standard prisoners' dilemma. Quite surprisingly, according to our results, only a strict additional equilibrium increases cooperation rate for a given time horizon. As expected a longer time horizon promotes cooperation.

Using a symmetric 2-person prisoners’ dilemma as the base game, each player receives a signal for the number of rounds to be played with the same partner. The actual number of rounds (the length of the supergame) is determined by the maximal signal where each player expects the other’s signal to be smaller, respectively larger, by a fixed number of rounds with 50% probability. In the tradition of Folk Theorems we show that both, mutual defection and mutual cooperation until the individually perceived last round, are subgame perfect equilibrium outcomes. We find experimental evidence that many players do in fact cooperate beyond their individual signal period.