Screening and Signaling in Communication*

In this paper, we analyze a model of repeated strategic communication between a sender and a receiver. The sender has private information on a policy‐relevant variable but does not know the receiver's motives. Together with the desire of the sender to please the receiver and the desire of the receiver to be pleased, the two‐sided incomplete information creates an interesting communication problem in which players can choose to use information strategically. We analyze various modes of communication, which allow for information transmission, and we compare them in terms of both the quality of the policy implemented and the welfare of the players.     

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.     

Morale,performance and disclosure

We study the optimal disclosure policy in a sender–receiver communication game where the receiver's morale, defined as his expected state of the world, affects his performance. The sender observes the state and chooses whether to disclose it to the receiver, who then decides whether to participate in a task. The receiver wins if his performance in the task meets a target. No disclosure is optimal if the receiver wins with average morale in each state. Otherwise, in the threshold disclosure equilibrium that Pareto-dominates full disclosure, the receiver quits as the sender discloses the worst states and wins as the sender withholds the rest. The receiver wins in more states in the Pareto-optimal equilibrium as the sender chooses a non-monotonic disclosure policy. Our theory reveals a trade-off between transparency and efficiency when morale affects performance. It has applications in a broad range of areas including military, family, education and business.     

Information design,externalities, and government interventions

We consider a model of Bayesian persuasion with spillovers. A sender provides information to persuade a receiver to take an action with external effects. We consider how government interventions, including corrective subsidy and tax, affect social welfare. In addition to internalizing externalities, government interventions affect social welfare through an informational channel. Subsidies to the sender's preferred action incentivize the sender to reveal less information, but taxes on the sender's preferred action incentivize the sender to reveal more information. Because of such an informational effect, the optimal subsidy and tax may be different from the size of the externalities. In some cases, social welfare is maximized with no government intervention.     

BAYESIAN PERSUASION WITH PRIVATE EXPERIMENTATION

This article studies a situation in which a sender tries to persuade a receiver by providing hard evidence that is generated by sequential private experimentation where the sender can design the properties of each experiment contingent on the experimentation history. The sender can selectively reveal as many outcomes as desired. We determine the set of equilibria that are not Pareto‐dominated. In each of these equilibria under private experimentation, the persuasion probability is lower and the receiver obtains access to higher quality information than under public experimentation. The decision quality improves in the sender's stakes.     

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.     

Endogenous Persuasion with Costly Verification

In this paper, I study a situation in which a sender tries to persuade a receiver with evidence that is generated via public or private experimentation. Under public experimentation, any experimental outcome is revealed, and under private experimentation the sender can hide adverse outcomes. The sender can design the properties of the experiments. The receiver chooses whether to verify at a cost the design of the experiment with which the revealed outcome was generated. I find that communication breaks down under public experimentation if there is no restriction on the experiment's design, and that persuasion is possible under private experimentation.     

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.     

Value of public information in sender-receiver games

I find in two classes of sender-receiver games that the receiver’s equilibrium payoff is not increasing in the informativeness of a public signal because the sender may transmit less information when the public signal is more informative.     

Signaling without a common prior: Results on experimental equilibrium selection

The common prior assumption is pervasive in game-theoretic models with incomplete information. This paper investigates experimentally the importance of inducing a correct common prior in a two-person signaling game. Equilibrium selection arguments predict that different equilibria may be selected depending on whether the common prior is induced or not. Indeed, for a specific probability distribution of the sender?s type, the long-run behavior without an induced common prior is shown to be different from the long-run behavior when a common prior is induced, while for other distributions long-run behavior is similar under both regimes. We also present a learning model that allows players to learn about the other players? strategies and the prior distribution of the sender?s type. We show that this learning model accurately accounts for all main features of the data.     

Enjoy the silence: an experiment on truth-telling

We analyze experimentally two sender–receiver games with conflictive preferences. In the first game, the sender can choose to tell the truth, to lie, or to remain silent. The latter strategy is costly. In the second game, the receiver must decide additionally whether or not to costly punish the sender after having observed the history of the game. We investigate the existence of two kinds of social preferences: lying aversion and preference for truth-telling. In the first game, senders tell the truth more often than predicted by the sequential equilibrium analysis, they remain silent frequently, and there exists a positive correlation between the probability of being truthful and the probability of remaining silent. Our main experimental result for the extended game shows that those subjects who punish the sender with a high probability after being deceived are precisely those who send fewer but more truthful messages. Finally, we solve for the Perfect Bayesian Nash Equilibria of a reduced form of the baseline game with two types of senders. The equilibrium predictions obtained suggest that the observed excessive truth-telling in the baseline game can be explained by lying aversion but not by a preference for truth-telling.

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Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users. Financial support through the Ramón y Cajal program of the Spanish Ministry of Education and Science is gratefully acknowledged. This work was initiated while the author was working at Maastricht University.     

Reputational cheap talk with misunderstanding

We consider a cheap talk game with a sender who has a reputational concern for an ability to predict a state of the world correctly, and where receivers may misunderstand the message sent. When communication between the sender and each receiver is private, we identify an equilibrium in which the sender only discloses the least noisy information. Hence, what determines the amount of information revealed is not the absolute noise level of communication, but the extent to which the noise level may vary. The resulting threshold in transmission noise for which information is revealed may differ across receivers, but is unrelated to the quality of the information channel. When information transmission has to be public, a race to the bottom results: the cut-off level for noise of transmitted information now drops to the lowest cut-off level for any receiver in the audience.     

WELFARE GAINS AND LOSSES IN SUNSPOT EQUILIBRIA*

We study a standard two period exchange economy with one nominal asset. As is well known, there is a continuum of sunspot equilibria around each efficient equilibrium. A sunspot equilibrium is inefficient but some households may gain in sunspot equilibria relative to the efficient equilibrium. We show that a household's equilibrium utility level is either locally maximized or locally minimized at the efficient equilibrium, and derive a condition which identifies whether or not a household's utility is locally minimized or maximized.     

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.     

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.     

An experiment on deception,reputation and trust

Experimental Economics - An experiment is designed to shed light on how deception works. The experiment involves a twenty period sender/receiver game in which period 5 has more weight than other...     

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.     

An experimental study of blind proficiency tests in forensic science

We conducted a series of sender?Creceiver experiments to study the consequences of implementing a regime of blind proficiency tests in forensic science to reduce error rates and improve the criminal justice system. Senders are our surrogate for forensic laboratories and receivers, for the judge or jury. Our experimental surrogate (random audits with a penalty) for blind proficiency tests reduced sender error rates by as much as 46% depending on the level of experimentally induced bias. When penalties improve information quality, receiver error rates fell by as much as 26% depending on the level of the sender bias. We also find that the penalty must be large relative to the payoff to induce the reduction in errors. Our results suggest that a regime of blind proficiency testing has the potential to reduce forensic science errors.     

GRANTING AN EXIT OPTION TO CONDUCT AN AUDIT

We study a principal–agent relationship with auditing in which information from an audit is ‘soft’– by conducting an audit, the principal observes the agent's private information, but cannot obtain verifiable evidence on the information. Moreover, the principal's auditing effort is unverifiable in our model. Therefore, besides the agent's misreporting incentive, there is the principal's incentive to accuse the truthful agent even without auditing. If the principal's auditing effort is verifiable, granting no exit option to the agent is optimal although the principal can still accuse a truthful agent after the audit. We show that when the principal's auditing effort is unverifiable, granting an exit option to the agent and auditing are complementary. Without granting an exit option to the agent, no auditing is optimal, and the principal grants an exit option to conduct a sincere audit, which in turn mitigates the agent's misreporting incentive. Our analysis also reveals that, when the cost of auditing is sufficiently large, the principal conducts more sincere audits with a smaller amount of penalty.     

Job market signaling and employer learning

We consider a signaling model where the sender?s continuation value after signaling depends on his type, for instance because the receiver is able to update his posterior belief. As a leading example, we introduce Bayesian learning in a variety of environments ranging from simple two-period to continuous-time models with stochastic production. Signaling equilibria present two major departures from those obtained in models without learning. First, new mixed-strategy equilibria involving multiple pooling are possible. Second, pooling equilibria can survive the Intuitive Criterion when learning is efficient enough.