MONEY TALKS? AN EXPERIMENTAL INVESTIGATION OF CHEAP TALK AND BURNED MONEY

We experimentally study the strategic transmission of information in a setting where both cheap talk and money can be used. Theoretically, many equilibria exist side by side, in which senders use either costless messages, money, or both. We find that senders prefer to communicate through costless messages. Only when the interest disalignment between sender and receiver increases does cheap talk tend to break down and high sender types start burning money to enhance the credibility of their costless messages. A behavioral model assuming that sellers bear a cost of lying fits the data best.     

Decentralized advice

We compare the amount of information credibly transmitted by cheap talk when information is centralized to one sender and when it is decentralized, with each of several senders holding a distinct but interdependent piece. Under centralization, full information transmission is typically impossible. Under decentralization, however, the number of receivers is decisive: decentralized communication with one receiver is completely uninformative, but decentralized communication with multiple receivers can be fully informative. We analyze the extent of such fully-informative communication, and apply our results to the issue of transparency in advisory committees.     

Cheap talk with two senders and complementary information

This paper studies a cheap talk model in which two senders having partial and non-overlapping private information simultaneously communicate with an uninformed receiver. The sensitivity of the receiverʼs ideal action to one senderʼs private information depends on the other senderʼs private information. We show that the sendersʼ information transmissions exhibit strategic complementarity: more information transmitted by one sender leads to more information being transmitted by the other sender.     

Cheap talk with multiple audiences: An experimental analysis

We examine strategic information transmission in a controlled laboratory experiment of a cheap talk game with one sender and multiple receivers. We study the change in equilibrium behavior from the addition of another audience as well as from varying the degree of conflict between the senderʼs and receiversʼ preferences. We find that, as in cheap talk games with just one receiver, information transmission is higher in games with a separating equilibrium, than in games with only a babbling equilibrium. More interestingly, we find clear evidence that the addition of another audience alters the communication between the sender and the receiver in a way consistent with the theoretical predictions. There is evidence of the presence of agents that are systematically truthful as senders and trusting as receivers: deviations from the theoretical predictions, however, tend to disappear with experience, and learning is faster precisely in the games where deviations are more pronounced.     

Authority and communication in the laboratory

We report findings from experiments on two delegation–communication games. An uninformed principal chooses whether to fully delegate her decision-making authority to an informed agent or to retain the authority and communicate with the agent via cheap talk to obtain decision-relevant information. In the game in which the delegation outcome is payoff-dominated by both the truthful and the babbling communication outcomes, we find that principal-subjects almost always retain their authority and agent-subjects communicate truthfully. Significantly more choices of delegation than of communication are observed in another game in which the delegation outcome payoff-dominates the unique babbling communication outcome; yet there is a non-negligible fraction of principal-subjects who holds on to their authority and agent-subjects who transmits some information. A level-k analysis of the game indicates that a principal-subject “under-delegates” due to the belief that her less-than-fully-strategic opponent will provide information; such belief is in turn consistent with the actual play.     

Markets for information: Of inefficient firewalls and efficient monopolies

In this paper we study market environments where information is costly to acquire and is also useful to potential competitors. Agents may sell, or buy, reports over the information acquired and choose their trades in the market on the basis of what they learnt. Reports are unverifiable – cheap talk messages – hence the quality of the information transmitted depends on the conflicts of interest faced by the senders. We find that, when information has a prevalent horizontal differentiation component, in equilibrium information is acquired when its costs are not too high and in that case it is also sold, though reports are typically noisy. The market for information is in most cases a monopoly, and there is underinvestment in information acquisition. We also show that regulatory interventions, in the form of firewalls, only make the inefficiency worse. Efficiency can be attained with a monopolist selling differentiated information, provided entry is blocked.     

Coordination with communication under oath

We focus on the design of an institutional device aimed to foster coordination through communication. We explore whether the social psychology theory of commitment, implemented via a truth-telling oath, can reduce coordination failure. Using a classic coordination game, we ask all players to sign voluntarily a truth-telling oath before playing the game with cheap talk communication. Three results emerge with commitment under oath: (1) coordination increased by nearly 50%; (2) senders’ messages were significantly more truthful and actions more efficient, and (3) receivers’ trust of messages increased.     

Self-enforced collusion through comparative cheap talk in simultaneous auctions with entry

Campbell (J Econ Theory 82:425–450, 1998) develops a self-enforced collusion mechanism in simultaneous auctions based on complete comparative cheap talk and endogenous entry, with two bidders. His result is difficult to generalize to an arbitrary number of bidders, since the entry-decision stage of the game is characterized by strategic substitutes. This paper analyzes more-than-two-bidder, symmetric-prior cases. Two results are proved: (1) as the number of objects grows large, a full comparative cheap talk equilibrium exists and it yields asymptotically fully efficient collusion; and (2) there is always a partial comparative cheap talk equilibrium. All these results are supported by intuitive equilibria at the entry-decision stage (J Econ Theory 130:205–219, 2006; Math Soc Sci 2008, forthcoming). Numerical examples suggest that full comparative cheap talk equilibria are not uncommon even with few objects.     

Comparative cheap talk

When are comparative statements credible? We show that simple complementarity conditions ensure that an expert with private information about multiple issues can credibly rank the issues for a decision maker. By restricting the expert's ability to exaggerate, multidimensional cheap talk of this form permits communication when it would not be credible in a single dimension. The communication gains can be substantial with even a couple of dimensions, and the complete ranking is asymptotically equivalent to full revelation as the number of issues becomes large. Nevertheless, partial rankings are sometimes more credible and/or more profitable for the expert than the complete ranking. Comparative cheap talk is robust to asymmetries that are not too large. Consequently, for sufficiently many independent issues, there are always some issues sufficiently symmetric to permit comparative cheap talk.     

INFORMATIONAL CASCADES ELICIT PRIVATE INFORMATION*

We introduce cheap talk in a dynamic investment model with information externalities. We first show how social learning adversely affects the credibility of cheap talk messages. Next, we show how an informational cascade makes truth‐telling incentive compatible. A separating equilibrium only exists for high‐surplus projects. Both an investment subsidy and an investment tax can increase welfare. The more precise the sender's information, the higher her incentives to truthfully reveal her private information.     

Credulity, lies, and costly talk

This paper studies a model of strategic communication by an informed and upwardly biased sender to one or more receivers. Applications include situations in which (i) it is costly for the sender to misrepresent information, due to legal, technological, or moral constraints, or (ii) receivers may be credulous and blindly believe the sender's recommendation. In contrast to the predictions obtained in the benchmark cheap talk model, our model admits a fully separating equilibrium, provided that the state space is unbounded above. The language used in equilibrium is inflated and naive receivers are deceived.     

A note on cheap talk and burned money

Austen-Smith and Banks [Cheap talk and burned money, J. Econ. Theory 91(1) (2000) 1-16] study how money burning can expand the set of pure cheap talk equilibria of Crawford and Sobel [Strategic information transmission, Econometrica 50(6) (1982) 1431-1451]. I identify an error in the main Theorem of Austen-Smith and Banks, and provide a variant that preserves some of the important implications. I also prove that cheap talk can be influential with money burning if and only if it can be influential without money burning. This strengthens a result of Austen-Smith and Banks, but uncovers other errors in their analysis. Finally, an open conjecture of theirs is proved correct.     

Equilibrium selection in experimental cheap talk games

In the past, many refinements have been proposed to select equilibria in cheap talk games. Usually, these refinements were motivated by a discussion of how rational agents would reason in some particular cheap talk games. In this paper, we propose a new refinement and stability measure that is intended to predict actual behavior in a wide range of cheap talk games. According to our Average Credible Deviation Criterion (ACDC), the stability of an equilibrium is determined by the frequency and size of credible deviations. ACDC organizes the results from several cheap talk experiments in which behavior converges to equilibrium, even in cases where other criteria do not make a prediction.     

Promises and lies: can observers detect deception in written messages

We design a laboratory experiment to examine predictions of trustworthiness in a novel three-person trust game. We investigate whether and why observers of the game can predict the trustworthiness of hand-written communications. Observers report their perception of the trustworthiness of messages, and make predictions about the senders’ behavior. Using observers’ decisions, we are able to classify messages as “promises” or “empty talk.” Drawing from substantial previous research, we hypothesize that certain factors influence whether a sender is likely to honor a message and/or whether an observer perceives the message as likely to behonored: the mention of money; the use of encompassing words; and message length. We find that observers have more trust in longer messages and “promises”; promises that mention money are significantly more likely to be broken; and observers trust equally in promises that do and do not mention money. Overall, observers perform slightly better than chance at predicting whether a message will be honored. We attribute this result to observers’ ability to distinguish promises from empty talk, and to trust promises more than empty talk. However, within each of these two categories, observers are unable to discern between messages that senders will honor from those that they will not.     

Communication in bargaining over decision rights

This paper develops a model of bargaining over decision rights between an uninformed principal and an informed but self-interested agent. We introduce two different bargaining mechanisms: tacit and explicit bargaining. In tacit bargaining, an uninformed principal makes a take-it-or-leave-it price offer to the agent, who then decides whether to accept or reject the offer. In the equilibrium of the game, the principal inefficiently screens out some agent types so that the agent's private information cannot be fully utilized when the decision is made. In explicit bargaining in which parties can communicate explicitly via cheap talk before tacit bargaining, however, an equilibrium with no such inefficient screening exists even when the conflict of interest is arbitrarily large. We also follow a mechanism design approach, showing that under certain conditions, explicit bargaining is an optimal bargaining mechanism that maximizes the joint surplus of the parties.     

For those about to talk we salute you: an experimental study of credible deviations and ACDC

We test the Average Credible Deviation Criterion (ACDC), a stability measure and refinement for cheap talk equilibria introduced in De Groot Ruiz et al. (Equilibrium selection in cheap talk games: ACDC rocks when other criteria remain silent, Working paper, University of Amsterdam 2012a). ACDC has been shown to be predictive under general conditions and to organize data well in previous experiments meant to test other concepts. In a new experimental setting, we provide the first systematic test of whether and to which degree credible deviations matter for the stability of cheap talk equilibria. Our principal experimental result is that in a setting where existing concepts are silent, credible deviations matter and matter gradually, as predicted by ACDC.     

Truthtelling in Matching Markets

We analyze a search and matching model with non‐transferable utility and asymmetric information. Randomly paired agents go through an evaluation phase, at the end of which they discover each other's types and choose to match or not. Before deciding to enter this phase, agents can communicate through cheap talk. We provide conditions for this communication to be informative, and we examine how it affects agents' welfare. We show that communication is Pareto‐improving only when the matching is assortative in the absence of communication and left unchanged by information transmission.     

Unmediated communication in games with complete and incomplete information

We study the effects of adding unmediated communication to static, finite games of complete and incomplete information. We characterize S^U(G), the set of outcomes of a game G, that are induced by sequential equilibria of cheap talk extensions. A cheap talk extension of G is an extensive-form game in which players communicate before playing G. A reliable mediator is not available and players exchange private or public messages that do not affect directly their payoffs. We first show that if G is a game of complete information with five or more players and rational parameters, then S^U(G) coincides with the set of correlated equilibria of G. Next, we demonstrate that if G is a game of incomplete information with at least five players, rational parameters and full support (i.e., all profiles of types have positive probability), then S^U(G) is equal to the set of communication equilibria of G.