Repetition, Communication, and Coordination Failure

We examine repetition as an institution that affects coordination failure in a game with and without pre-play communication. We use probit regression with random effects to test hypotheses regarding the frequency and form of coordination failure in the presence of repeated play versus one-shot games. Our results indicate that repetition without pre-play communication results in a lower frequency of coordination failure relative to one-shot game outcomes. This result is reversed when pre-play communication is allowed. Our evidence also suggests that repeated play coordination failures tend to be suboptimal Nash equilibria, whereas one-shot game coordination failures are disequilibria regardless of the presence of pre-play communication.     

Credible communication and cooperation: Experimental evidence from multi-stage Games

It is well known that communication often serves as a facilitator for cooperation in static games. Yet, communication can serve entirely different purposes in dynamic settings as communication during the game may work as a means for renegotiation, potentially undermining the credibility of cooperative strategies. To explore this issue, this paper experimentally investigates cooperation and non-binding communication in a two-stage game. More specifically, two treatments are considered: one with only pre-play communication and one where subjects can also communicate intra-play between the stages of the game. The results highlight a nontrivial difference concerning the effects of pre-play communication between the two treatments. Sending or receiving pre-play messages has a positive and significant effect on cooperation if there is no possibility of intra-play communication. However, this effect is significantly reduced when when intra-play communication is allowed. The results suggest that the credibility of pre-play messages may depend crucially on future communication opportunities.     

Self-Serving Cheap Talk: A Test Of Aumann's Conjecture

The effectiveness of pre-play communication in achieving efficient outcomes has long been a subject of controversy. Aumann conjectures that, in a variant of the Stag Hunt game, “an agreement to play [the efficient outcome] conveys no information about what the players will do” and thus should not affect behavior. Farrell and Rabin suspect that cheap talk will achieve efficiency. Results show impressive coordination when the sender first chooses a signal and then an action. Without communication, efforts to achieve efficiency are largely unsuccessful. As Farrell suggests, reversing the order of the action and signal appears to change players' behavior. Journal of Economic Literature Classification Numbers: A13, C72, C91, D82, D84.     

Computationally restricted unmediated talk under incomplete information

Summary. We show the role of unmediated talk with computational complexity bounds as both an information transmission and a coordination device for the class of two-player games with incomplete information and rational parameters. We prove that any communication equilibrium payoff of such games can be reached as a Bayesian-Nash equilibrium payoff of the game extended by a two phase universal mechanism of interim computationally restricted pre-play communication. The communication protocols are designed with the help of modern cryptographic tools. A familiar context in which our results could be applied is bilateral trading with incomplete information.Received: 9 September 2002, Revised: 14 March 2003, JEL Classification Numbers: C72. Correspondence to: Amparo UrbanoWe wish to thank financial aid from the Valencian Institute of Economic Research (IVIE) and partial support by DIGCYT under project PB95 - 1074. A previous version of this work appears as IVIE Working Paper WP-AD 99-07, under the title: "Unmediated talk under incomplete information".     

Whatever you say, your reputation precedes you: Observation and cheap talk in the trust game

Behavior in trust games has been linked to general notions of trust and trustworthiness, important components of social capital. In the equilibrium of a trust game, the investor does not invest, foreseeing that the allocator would keep all of the returns. We use a human-subjects experiment to test the effects of changes to the game designed to increase cooperation and efficiency. We add a pre-play stage in which the investor receives a cheap-talk message from the allocator, observes the allocator's previous decision, or both. None of these changes alter the game's theoretical predictions. We find that allowing observation results in substantially higher cooperation and efficiency, but cheap talk has little effect.     

Pre-play communication with forgone costly messages: experimental evidence on forward induction

We experimentally study optional costly communication in Stag-Hunt games. Prior research demonstrates that efficient coordination is difficult without a communication option but obtains regularly with mandatory costless pre-play messages. We find that even small communication costs dramatically reduce message use when communication is optional, but efficient coordination can occur with similar frequency as under costless communication. These findings can be accounted for by formalizations of forward induction that take Nash equilibrium as a reference point (such as Kohlberg and Mertens in Econometrica 54: 1003–1037, 1986; Govindan and Wilson in Econometrica 77: 1–28, 2009), while formalizations that only appeal to (higher-order) knowledge of rationality remain silent in this environment.     

Inter-gender interaction and communication in ultimatum games

In this article, we focus on bargaining within male–female pairs, the most pervasive partnership in humankind. We analyse data from an ultimatum game played by Greek participants. Parallel to this, we introduce a one-way communication protocol according to which the responders can send short messages to the receivers, after making their decisions. The analysis shows that gender and message effects exist and males are more effective bargainers.     

How does the effect of pre-play suggestions vary with group size? Experimental evidence from a threshold public-good game

Numerous studies have examined factors influencing the likelihood of cooperative outcomes in nonzero-sum games, but there has been little study of the interaction between two of the most important: group size and pre-play cheap talk. We report results from an experiment in which groups of size between 2 and 15 play a one-shot multi-player threshold public-good game. In our random leader treatment, all group members select a suggestion (e.g., “Everyone should choose X”), with one randomly chosen to be broadcast to the group. In a choice only treatment, subjects choose suggestions but none is sent, and in a baseline treatment, there are no suggestions at all. We find a negative interaction between group size and this kind of communication: the beneficial effect of both suggestions overall and cooperative suggestions on cooperation, cooperative outcomes, and payoffs decreases sharply as the group size increases. We find a similar negative interaction in a follow-up treatment in which all group members’ suggestions are broadcast to the group. Our results suggest that care should be taken in generalising conclusions from small-group experiments to large groups.     

Indirect higher order beliefs and cooperation

This study experimentally examines the role of indirect higher order beliefs in sequential psychological games. We consider a three-player sequential game in which the first and third players do not interact sequentially, but only through an intermediary, the second player. We posit that the third player’s decision to cooperate depends on his indirect higher order belief, namely, his belief about what the first player believes the second player would choose. We employ pre-play communication between the first and third players as a way to influence the third player’s indirect higher order belief. The evidence demonstrates that communication can effectively induce cooperation from the third player by shaping his indirect higher order belief.     

Message spaces for perfect correlated equilibria

Summary. We show that a perfect correlated equilibrium distribution of an N-person game, as defined by Dhillon and Mertens (1996) can be achieved using a finite number of copies of the strategy space as the message space.Received: 31 August 2004, Revised: 1 April 2005, JEL Classification Numbers: C72.Srihari Govindan: Correspondence toGovindan would like to thank the Social Sciences and Humanities Research Council of Canada for research support.     

Cheap talk in games with incomplete information

The paper studies Bayesian games which are extended by adding pre-play communication. Let Γ be a Bayesian game with full support and with three or more players. The main result is that if players can send private messages to each other and make public announcements then every communication equilibrium outcome, q, that is rational (i.e., involves probabilities that are rational numbers) can be implemented in a sequential equilibrium of a cheap talk extension of Γ, provided that the following condition is satisfied: There exists a Bayesian Nash equilibrium s in Γ such that for each type t_i of each player i the expected payoff of t_i in q is larger than the expected payoff of t_i in s.     

More than words: the effects of cheap talk in a volunteer’s dilemma

We theoretically and experimentally investigate a game in which exactly one person should make a costly effort to achieve a socially efficient outcome. This setting is commonly known as the volunteer’s dilemma. We implement one-way communication by allowing one player to send a message indicating whether she intends to volunteer and investigate the message’s effects on behavior and efficiency in the subsequent game. We theoretically demonstrate that there are asymmetric mixed-strategy equilibria in the volunteer’s dilemma and argue that one of these is likely to emerge through one-way communication. The experimental data support this notion. We find that the actions of both the sender and receiver of the message are crucially affected by the cheap talk stage and that efficiency in the volunteer’s dilemma increases with one-way communication.     

On core stability, vital coalitions, and extendability

If a TU game is extendable, then its core is a stable set. However, there are many TU games with a stable core that are not extendable. A coalition is vital if there exists some core element x such that none of the proper subcoalitions is effective for x. It is exact if it is effective for some core element. If all coalitions that are vital and exact are extendable, then the game has a stable core. It is shown that the contrary is also valid for matching games, for simple flow games, and for minimum coloring games.     

Stackelberg-solvable games and pre-play communication

The concept of Stackelberg-solvable games is introduced and analyzed as a generalization of 2-person zero-sum games. Then, the problem of sincere pre-play communication is examined and the incentive compatibility of the Nash-equilibrium selection is shown to correspond to the Stackelberg-equilibrium property.     

Harmful lie aversion and lie discovery in noisy expert advice games

This study tests whether individuals are reluctant to tell lies, or perhaps only “harmful lies”, in a previously untested environment: an expert sending a message to a decision maker whose interpretation of that message is subject to error, i.e. a noisy sender–receiver game. In the Aligned treatment, the expert can send a “white lie” to the receiver, eliminating the negative effects of noise and improving both parties’ payoffs. In the Conflict treatment, lies are harmful and the inability to commit to truthtelling destroys all meaningful communication in equilibrium unless there is a cost of lying. In the experiment, receivers are overly trusting and experts learn to take advantage of this. As experts gain experience they tell stronger and more frequent lies in both treatments, consistent with models of reinforcement learning. The findings suggest that neither harmful nor universal lie aversion is a factor when communication is noisy, provided individuals have time to discover their personal benefits of lies.     

More Is Better, But Fair Is Fair: Tipping in Dictator and Ultimatum Games

This paper examines Allocators' willingness to reward and punish their paired Recipients. Recipients only compete in a skill-testing contest, the outcome of which determines the size of the surplus. In the dictator game, Allocators reward skillful Recipients, but punish unskillful ones only modestly. The punishment effect is mitigated by the belief held by some Allocators thateffortis the appropriate measure of deservingness. The ultimatum game extension reveals offerers' ability to adapt to the strategic environment. Offers to skillful Recipients in the ultimatum game, however, are shown to be motivated by a taste for fairness, and not strategic considerations.Journal of Economic LiteratureClassification Numbers: C70, C91, D63.     

Perturbed communication games with honest senders and naive receivers

This paper studies communication games in which the sender is possibly honest (tells the truth) and the receiver is possibly naive (follows messages as if truthful). The characterization of message-monotone equilibria in the perturbed games explain several important aspects of strategic communication including sender exaggeration, receiver skepticism and message clustering. Surprisingly, the strategic receiver may respond to more aggressive claims with more moderate actions. In the limit as the probabilities of the non-strategic players approach zero, (i) the limit equilibrium corresponds to a most-informative equilibrium of the limit (Crawford-Sobel) game; (ii) only the top messages are sent.     

Co-ordination, Spillovers, and Cheap Talk

We analyze the role of cheap-talk in two player games with one-sided incomplete information. We identify conditions under which (1) players can fully communicate and coordinate on efficient Nash equilibria of the underlying complete information game; and (2) players cannot communicate so cheap-talk does not alter the equilibrium set of the Bayesian game. We present examples that illustrate several issues that arise when there is two-sided incomplete information. Journal of Economic Literature Classification Numbers: C72, D82.