We enrich a simple two-person bargaining model by introducing “behavioral types” who concede more slowly than does the average person in the economy. The presence of behavioral types profoundly influences the choices of optimizing types. In equilibrium, concessions are calculated to induce “reciprocity”: a substantial concession by player i is followed by a period in which j is much more likely to make a concession than usual. This favors concessions by i that are neither very small nor large enough to end the bargaining immediately. A key difference from the traditional method of perturbing a game is that the actions of our behavioral types are not specified in absolute terms, but relative to the norm in the population. Thus their behavior is determined endogenously as part of a social equilibrium.
It seems reasonable to suppose that in repeated games in which communications is possible, play is determined through a process of negotiation and renegotiation as events unfold. In the absence of a satisfying theory of players’ bargaining power, it is unclear how to model this process. Symmetric repeated games are an important class in which the problem is less troublesome. Whatever its source, bargaining power is presumably the same for all players in a symmetric game. We take equal bargaining power to mean that a player can mount a credible objection to a continuation equilibrium in which he receives a particular expected present discounted value, if there are other self enforcing agreements that never give any player such a low continuation value after any history. This is formalized in a solution concept called consistent bargaining equilibrium.
In a repeated partnership game with imperfect monitoring, we distinguish among the effects of (1) shortening the period over which actions are held fixed, (2) increasing the frequency with which accumulated information is reported, and (3) reducing the amount of discounting of payoffs between successive periods. While reducing the amount of discounting generally improves incentives for cooperation, the other two changes can have the reverse effect. When the game is specified in the customary way with information reported at the end of each period of fixed action, the net effect of shortening the period length can be to destroy all incentives for cooperation, reversing the usual conclusion associated with the Folk Theorem for repeated games. Moreover, when interest rates are low, reducing the frequency of information reporting can greatly enhance the efficiency of equilibrium.
JEL Classification: 026
Keywords: Monitoring, Repeated games, Partnership, Incentives, Folk theorems
This paper investigates pure strategy sequential equilibria of repeated games with imperfect monitoring. The approach emphasizes the equilibrium value set and the static optimization problems embedded in external equilibria. We characterize these equilibria, and provide computational and comparative statics results. The “self-generation” and “bang-bang” propositions which were at the core of our analysis of optimal cartel equilibria [2], are generalized to asymmetric games and infinite action spaces. New results on optimal implicit reward functions include the necessity (as opposed to sufficiency) of bang-bang functions, and the nature of optimal punishment regions.
JEL Classification: 026
Keywords: Pure strategy sequential equilibria, Repeated games, Imperfect monitoring
There exist optimal symmetric equilibria in the Green-Porter model [5, 8] having an elementary intertemporal structure. Such an equilibrium is described entirely by two subsets of price space and two quantities, the only production levels used by firms in any contingency. The central technique employed in the analysis is the reduction of the repeated game to a family of static games.