Payoff levels, loss avoidance, and equilibrium selection in the Stag Hunt: an experimental study

Game theorists typically assume that changing a game’s payoff levels—by adding the same constant to, or subtracting it from, all payoffs—should not affect behavior. While this invariance is an implication of the theory when payoffs mirror expected utilities, it is an empirical question when the “payoffs” are actually money amounts. In particular, if individuals treat monetary gains and losses differently, then payoff–level changes may matter when they result in positive payoffs becoming negative, or vice versa. We report the results of a human–subjects experiment designed to test for two types of loss avoidance: certain–loss avoidance (avoiding a strategy leading to a sure loss, in favor of an alternative that might lead to a gain) and possible–loss avoidance (avoiding a strategy leading to a possible loss, in favor of an alternative that leads to a sure gain). Subjects in the experiment play three versions of Stag Hunt, which are identical up to the level of payoffs, under a variety of treatments. We find differences in behavior across the three versions of Stag Hunt; these differences are hard to detect in the first round of play, but grow over time. When significant, the differences we find are in the direction predicted by certain– and possible–loss avoidance. Our results carry implications for games with multiple equilibria, and for theories that attempt to select among equilibria in such games.

Horizontal Agreements and R&D Complementarities: Merger versus RJV

We study the decision of two rms within an oligopoly concerning whether to enter into a horizontal agreement to exploit complementarities between their R&D activities and, if so, whether to merge or form a research joint venture (RJV). In contrast to horizontal merger, there is a probability that an RJV contract will fail to enforce R&D sharing. We nd that a horizontal agreement always arises. The insiders' merger/RJV choice involves a trade-o : While merger o ers certainty that R&D complementarities will be exploited, it leads to a pro t-reducing reaction by outsiders on the product market, where competition is Cournot. Greater brand similarity and contract enforceability (\quality") both favour RJV, while greater R&D complementarity favours merger. Interestingly, the insiders may choose to merge even when RJV contracts are always enforceable, and they may opt to form an RJV even when the likelihood of enforceability is negligible.