STRATEGIC AND SOCIAL PREPLAY COMMUNICATION IN THE ULTIMATUM GAME

Pre-play face-to-face communication is known to facilitate cooperation. Various explanations exist for this effect, varying in their dependence on the strategic content of the communication. Previous studies have found similar communication effects regardless of whether strategic communication is available. These results were so far taken to support a social-preferences based explanation of the communication effects. The current experiment provides a replication and extension of previous results to show that different processes come into play, depending on the communication protocol. Specically, pre-play communication in an ultimatum game was either restricted to nongame- related content or unrestricted. The results show that strategic, but not social, communication affects responders' strategies. Thus, the existing results are cast in a new light. I conclude that pre-play communication effects may be mediated by qualitatively dierent processes, depending on the social context.

See No Evil: Information Chains and Reciprocity in Teams

Transparency in teams can facilitate cooperation. We study contribution decisions by agents when previous decisions can be observed. We find that an information chain, in which each agent directly observes only the decision of her immediate predecessor, is at least as effective as a fully-transparent protocol in inducing cooperation under increasing returns to scale. In a comparable social dilemma, the information chain leads to high cooperation both in early movers when compared to a non-transparent protocol and in late movers when compared to a fully-transparent protocol. we conclude that information chains facilitate cooperation by balancing positive and negative reciprocity.team production, public goods, incentives, externality, information, transparency, conditional cooperation

Timing of Messages and the Aumann Conjecture: A multiple-Selves Approach

The Aumann (1990) conjecture states that cheap-talk messages do not necessarily help to coordinate on efficient Nash equilibria. In an experimental test of Aumann’s conjecture, Charness (2000) found that cheap-talk messages facilitate coordination when they precede the action, but not when they follow the action. Standard game-theoretical modeling abstracts from this timing effect, and therefore cannot account for it. To allow for a formal analysis of the timing effect, I study the sequential equilibria of the signaling game in which the sender is modeled as comprising two selves: an acting self and a signaling self. I interpret Aumann’s argument in this context to imply that all of the equilibria in this game are ‘babbling’ equilibria, in which the message conveys no information and does not affect the behavior of the receiver. Using this framework, I show that a fully communicative equilibrium exists—only if the message precedes the action but not when the message follows the action. In the latter case, no information is transmitted in any equilibrium. This result provides a game-theoretical explanation for the puzzling experimental results obtained by Charness (2000). I discuss other explanations for this timing-of-message effect and their relationship to the current analysis.pre-play communication, Nash equilibrium, coordination games, multiple selves

Auctions and Leaks: A Theoretical and Experimental Investigation

We study first- and second-price private value auctions with sequential bidding where second movers may discover the first movers bids. There is a unique equilibrium in the first-price auction and multiple equilibria in the second-price auction. Consequently, comparative statics across price rules are equivocal. We experimentally find that in the first-price auction, leaks benefit second movers but harm first movers and sellers. Low to medium probabilities of leak eliminate the usual revenue dominance of first-price over second-price auctions. With a high probability of a leak, second-price auctions generate higher revenue