https://www.elias-tsakas.com/research/ Recent content in Research on Elias Tsakas Hugo en-us Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/affectivepolarization/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/affectivepolarization/ <div class="tc"> <p>(with Maxim Doiron, <a href="https://www.maastrichtuniversity.nl/km-thomsson/research">Kaj Thomsson</a> and <a href="https://www.vostroknutov.com">Alexander Vostroknutov</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/AffectivePolarization.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>The rise in polarization in American politics over recent decades has attracted plenty of interest both in academia and in the broader public discussion. However, the connection between affective polarization and individuals' election expectations is virtually unexplored and poorly understood. Exploring this connection is critical to our understanding of the underlying mechanisms of rising affective polarization; there may, for instance, exist a link between violated election expectations and support for extreme post-election reactions. In October 2020, we asked a set of survey participants to complete positive and negative partisanship scales as well as their probabilistic assessments of the presidential candidates' chances of winning. For both Democrats and Republicans we found a strong positive association between negative partisanship and the likelihood of winning assigned by voters to the presidential candidate of the same party. This indicates that there is a link between affective polarization and election expectations, and that negative partisanship may be the most important facet of that relationship.</p> https://www.elias-tsakas.com/research/aggregateinformationnobet/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/aggregateinformationnobet/ <div class="tc"> <p class="f3"><strong><em>International Journal of Game Theory</em></strong></p> <p><a href="https://www.elias-tsakas.com/files/paper.pdf">Journal publication (open access)</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>This note considers gambles that take place even if only some — but not all — individuals agree to participate. I show that the bet cannot take place if it is commonly known how many individuals are willing to participate.</p> </div> https://www.elias-tsakas.com/research/agreementcps/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/agreementcps/ <div class="tc"> <p class="f3"><strong><em>B.E. Journal of Theoretical Economics</em></strong></p> <p><a href="https://www.degruyterbrill.com/journal/key/bejte/html">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/AgreementCPS.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In this note, we extend Aumann's agreement theorem to a framework where beliefs are modelled by conditional probability systems a la Battigalli and Siniscalchi (1999). We prove two independent generalizations of the agreement theorem, one where the agents share some common conditioning event, and one where they may not.</p> </div> https://www.elias-tsakas.com/research/marginaleffects/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/marginaleffects/ <div class="tc"> <p class="f3"><strong><em>Applied Economics</em></strong></p> <p>(with <a href="https://www.gu.se/en/about/find-staff/alpaslanakay">Alpaslan Akay</a>)</p> <p><a href="https://www.tandfonline.com/doi/abs/10.1080/00036840600994096">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/MarginalEffectsAE.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In this paper we discuss the differences between the average marginal effect and the marginal effect of the average individual in sample selection models, estimated by the Heckman procedure. We show that the bias that emerges as a consequence of interchanging them, could be very significant, even in the limit. We suggest a computationally cheap approximation method, which corrects the bias to a large extent. We illustrate the implications of our method with an empirical application of earnings assimilation and a small Monte Carlo simulation.</p> https://www.elias-tsakas.com/research/identificationproxy/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/identificationproxy/ <div class="tc"> <p class="f3"><strong><em>Review of Economic Studies</em></strong></p> <p><a href="https://academic.oup.com/restud/article/93/1/697/8114609?login=false">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/IdentificationBeliefs.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/IdentificationBeliefsSlides.pdf">Presentation</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>It is well known that individual beliefs cannot be identified using traditional choice data, unless we exogenously assume state-independent utilities. In this paper, I propose a novel methodology that solves this long-standing identification problem in a simple way. This method relies on the extending the state space by introducing a proxy, for which the agent has no stakes conditional on the original state space. The latter allows us to identify the agent's conditional beliefs about the proxy given each state realization, which in turn suffices for indirectly identifying her beliefs about the original state space. This approach is analogous to the one of instrumental variables in econometrics. Similarly to instrumental variables, the appeal of this method comes from the flexibility in selecting a proxy.</p> https://www.elias-tsakas.com/research/updatingmisinformation/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/updatingmisinformation/ <div class="tc"> <p>(with <a href="https://www.larswittrock.eu">Lars Wittrock</a> and <a href="https://martinstrobel.net">Martin Strobel</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/UpdatingMisinformation.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In this paper we study experimentally how people process verifications of previously received information. We propose a theoretical model that builds on the standard framework of Grether (1980) to provide a unified mechanism that describes how people react to retractions and confirmations. Our data corroborates the predictions of this model, showing that reactions to verifications are explained by the prior beliefs, i.e., for low priors subjects underreact to retractions and overreact to confirmations, whereas for high priors they overreact to retractions and underreact to confirmations. Our explanation is consistent with the idea that people overreact to unexpected information, which is a direct consequence of base rate neglect within our model. Our findings are qualitatively robust in various dimensions that we tested, and indicate that the way people react to retractions is more nuanced than it has been thought so far.</p> https://www.elias-tsakas.com/research/btib/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/btib/ <div class="tc"> <p>(with <a href="https://egorbronnikov.github.io">Egor Bronnikov</a>, <a href="https://www.maastrichtuniversity.nl/km-thomsson/research">Kaj Thomsson</a> and <a href="https://www.vostroknutov.com">Alexander Vostroknutov</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/BTIB.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Increasing political polarization in the United States has led individuals to process information in ways that reinforce their prior beliefs, often dismissing sources associated with opposing views or the other party. While partisan-motivated rea- soning provides a well-established explanation for this phenomenon, we investigate and document a largely overlooked determinant: the role of surprise in belief updating. Using two experimental studies, we exposed participants to identi- cal political information about the likely outcome of the 2024 presidential elec- tion, while varying its source, and measured belief updating via the Log-Likelihood Ratio. Results show that belief updating was primarily driven by the level of sur- prise, not source credibility. Counter-stereotypical signals —when a source provided unexpected information— elicited stronger updates, overriding partisan bias. Our findings suggest that surprise disrupts ideological echo chambers, challenging entrenched beliefs more effectively than source alignment alone.</p> https://www.elias-tsakas.com/research/choiceviaai/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/choiceviaai/ <div class="tc"> <p>(with <a href="https://sites.google.com/site/janchristopherkops">Christopher Kops</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/AI.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>This paper proposes a model of choice via agentic artificial intelligence (AI). A key feature is that the AI may misinterpret a menu before recommending what to choose. A single acyclicity condition guarantees that there is a monotonic interpretation and a strict preference relation that together rationalize the AI's recommendations. Since this preference is in general not unique, there is no safeguard against it misaligning with that of a decision maker. What enables the verification of such AI alignment is interpretations satisfying double monotonicity. Indeed, double monotonicity ensures full identifiability and internal consistency. But, an additional idempotence property is required to guarantee that recommendations are fully rational and remain grounded within the original feasible set.</p> https://www.elias-tsakas.com/research/cbfr/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/cbfr/ <div class="tc"> <p class="f3"><strong><em>Mathematical Social Sciences</em></strong></p> <p>(with Angie Mounir and <a href="http://www.epicenter.name/Perea/">Andres Perea</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0165489617301312">Journal publication</a> / <a href="https://www.elias-tsakas.com/files/papers/CBFR.pdf">Working Paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>This paper substitutes the standard rationality assumption with approximate rationality in normal form games. Players are assumed to be \(\varepsilon\)-rational, i.e. willing to settle for a suboptimal choice, and so give up an amount \(\varepsilon\) of expected utility, in response to the belief they hold about their opponents' choices. For every player \(i\) and every opponents' degree of rationality \(\varepsilon\), we require player \(i\) to attach at least probability \(F_i(\varepsilon)\) to his opponent being \(\varepsilon\)-rational, where the functions \(F_i\) are assumed to be common knowledge. We refer to this event as belief in \(F\)-rationality. The notion of Common Belief in \(F\)-Rationality (CBFR) is then introduced as an approximate rationality counterpart of the established Common Belief in Rationality. Finally, a corresponding recursive procedure is designed that characterizes those beliefs players can hold under CBFR.</p> https://www.elias-tsakas.com/research/cbwdr/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/cbwdr/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p>(with <a href="https://faculty.econ.ucdavis.edu/faculty/bonanno/">Giacomo Bonanno</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0899825618301441?via 3Dihub">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/Qualitative.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We study common belief of weak-dominance rationality in strategic-form games with ordinal utilities, employing a qualitative model of beliefs. We characterize two standard solution concepts for such games: the Iterated Deletion of Borgers-dominated Strategies (IDBS) and the Iterated Deletion of Inferior Strategy Profiles (IDIP). We do so by imposing nested restrictions on the doxastic models: namely, the respective epistemic conditions differ in the fact that IDIP requires the truth axiom whereas IDBS does not. Hence, IDIP refines IDBS. </p> https://www.elias-tsakas.com/research/cpendogenousuncertainty/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/cpendogenousuncertainty/ <div class="tc"> <p class="f3"><strong><em>Journal of Economic Theory</em></strong></p> <p>(with <a href="https://www.pf-guarino.com/">Pierfrancesco Guarino</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/pii/S0022053121000715">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/EndogenousUncertaintyCP.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>For a fixed game and a type structure that admits a common prior, Action Independence states that the conditional beliefs induced by the common prior do not depend on the player’s own strategy. It has been conjectured that Action Independence can be behaviorally characterized by means of a suitable no-betting condition (Dekel & Siniscalchi, 2015), but whether this is indeed the case remains an open problem. In this paper, we prove this conjecture true by focusing on strategy-invariant bets, which are bets that cannot be manipulated by the players. In particular, first we show that at least one of the common priors satisfies Action Independence if and only if there exists no mutually acceptable strategy-invariant bet among the players. Second we show that, all common priors satisfy Action Independence if and only if there exists no mutually acceptable strategy-invariant bet among the players and an outside observer. These results allow us a deeper understanding of existing foundations of solution concepts using only epistemic conditions that are expressed in terms of type structures and are therefore elicitable.</p> https://www.elias-tsakas.com/research/cbe/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/cbe/ <div class="tc"> <p class="f3"><strong><em>Synthese</em></strong></p> <p><a href="http://link.springer.com/article/10.1007/s11229-015-0791-4">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/CBE.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We introduce a new solution concept, called correlated-belief equilibrium. The difference to Nash equilibrium is that, while each player has correct marginal conjectures about each opponent, it is not necessarily the case that these marginal conjectures are independent. Then, we provide an epistemic foundation and we relate correlated-belief equilibrium with standard solution concepts, such as rationalizability, correlated equilibrium and conjectural equilibrium.</p> </div> https://www.elias-tsakas.com/research/epistemicequivalence/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/epistemicequivalence/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0899825614000529">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/EpistemicEquivalenceGEB.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In this paper, we introduce a notion of epistemic equivalence between hierarchies of conditional beliefs and hierarchies of lexicographic beliefs, thus extending the standard equivalence results of Halpern (2010) and Brandenburger et al. (2007) to an interactive setting, and we show that there is a Borel surjective function, mapping each conditional belief hierarchy to its epistemically equivalent lexicographic belief hierarchy. Then, using our equivalence result we construct a terminal type space model for lexicographic belief hierarchies. Finally, we show that whenever we restrict attention to full-support beliefs, epistemic equivalence between a lexicographic belief hierarchy and a conditional belief hierarchy implies that an arbitrary Borel event is commonly assumed under the lexicographic belief hierarchy if and only if it is commonly strongly believed under the conditional belief hierarchy. This is the first result in the literature directly linking common assumption in rationality (Brandenburger et al., 2008) with common strong belief in rationality (Battigalli and Siniscalchi, 2002).</p> https://www.elias-tsakas.com/research/expectedaccuracy/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/expectedaccuracy/ <div class="tc"> <p>(with <a href="https://egorbronnikov.github.io">Egor Bronnikov</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/RobustComplexity.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/RobustComplexitySlides.pdf">Presentation</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We introduce uniform expected accuracy as a proxy for subjective complexity which is robust with respect to the underlying reward for solving the task correctly. The idea is that task A is classified as subjectively more complex than task B if the probability of correctly solving A is smaller than the probability of correctly solving B for any reward. We provide a full characterization of the incomplete order over the set of tasks that this criterion induces. This characterization implies that task A will be classified as subjectively more complex than task B if and only if A is both more difficult and much less known than B. This insight is consistent with the general idea within economics that complexity has both an objective and a subjective part. It is also aligned with the literature in psychology and information science which ---unlike economics--- have identified prior uncertainty as a key dimension of complexity. Then, using a lab experiment, where we can exogenously control both difficulty and uncertainty, we corroborate our theoretical predictions. Thus, the recently surging use of expected accuracy in economics as a proxy for subjective complexity is well warranted, as long as expected accuracy is elicited for multiple different rewards using the strategy method.</p> https://www.elias-tsakas.com/research/partizanshipupdating/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/partizanshipupdating/ <div class="tc"> <p class="f3"><strong><em>Journal of Experimental Psychology: General</em></strong></p> <p>(with <a href="https://scholar.google.com/citations?user=DZlLAN0AAAAJ&hl=el">Giannis Lois</a> and <a href="https://www.arnoriedl.com">Arno Riedl</a>)</p> <p><a href="https://doi.org/10.1037/xge0001815">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/PartizanshipUpdating.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>A prominent explanation for the proliferation of political misinformation and the growing belief polarization is that people engage in motivated reasoning to affirm their ideology and to protect their political identities. An alternative explanation is that people seek the truth but use partisanship as a heuristic to discern credible from dubious sources of political information. In two experiments, we test these competing explanations in a dynamic setting where Democrats and Republicans are repeatedly exposed to messages from ingroup or outgroup partisan sources and can gradually learn which source is credible based on external feedback. Both Democrats and Republicans initially incorporated information from ingroup sources more than from outgroup sources. This pattern was stronger among partisans that displayed high affective polarization. Across rounds, this partisan bias declined, or even changed direction, as supporters of both groups gradually incorporated information from reliable sources more than unreliable sources irrespective of the source’s partisanship. Importantly, the content of the shared information (i.e., neutral vs political) and the presence of partisan sources as opposed to neutral sources did not affect the learning process indicating the presence of strong accuracy motives. In contrast, increased uncertainty regarding source reliability undermined the learning process. These findings demonstrate that partisans follow Bayesian learning dynamics. Although they initially display a partisan bias in the incorporation of information, they overcome this bias in the presence of external feedback and learn to trust credible sources irrespective of partisanship. </p> https://www.elias-tsakas.com/research/pdps/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/pdps/ <div class="tc"> <p class="f3"><strong><em>Computer Aided Chemical Engineering</em></strong></p> <p>(with <a href="https://www.researchgate.net/profile/Aleksandra-Zderic-2">Aleksandra Zderic</a>, <a href="https://www.researchgate.net/profile/Alexandra-Kiskini">Alexandra Kiskini</a>, <a href="https://www.researchgate.net/profile/Cristhian-Almeida-Rivera">Cristhian Almeida Rivera</a> and <a href="https://people.utwente.nl/e.zondervan">Edwin Zondervan</a>)</p> <p><a href="https://www.sciencedirect.com/science/chapter/bookseries/abs/pii/B9780128186343502666">Journal publication</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In the first years of the 2000's the late professor Peter Bongers introduced together with his co-workers at Unilever a design methodology that could be applied in the development of new products and processes for structured food products; the product-driven process synthesis method (PDPS). The method was successfully employed in the following years, designing new products from different bio based sources. Although researchers used the method and even made improvements; the structural incorporation of mathematical programming tools has been lacking and this seems to be a crucial component for decision-making processes. In this contribution we will discuss the possibilities to extend the PDPS framework with several of these optimization tools.</p> https://www.elias-tsakas.com/research/growthinequalitypgg/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/growthinequalitypgg/ <div class="tc"> <p class="f3"><strong><em>Journal of Public Economics</em></strong></p> <p>(with <a href="https://www.nottingham.ac.uk/economics/people/simon.gaechter">Simon Gaechter</a>, <a href="https://sites.google.com/site/friederikemengel/">Friederike Mengel</a> and <a href="https://www.vostroknutov.com">Alexander Vostroknutov</a>)</p> <p><a href="http://www.sciencedirect.com/science/article/pii/S0047272717300361">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/PubGrowth.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/PubGrowthApp.pdf">Online Appendix</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In a novel experimental design we study public good games with dynamic interdepen- dencies, where each agent’s wealth at the end of period t serves as her endowment in t+1. In this setting growth and inequality arise endogenously allowing us to address new questions regarding their interplay and effect on cooperation. We find that amounts contributed are increasing over time even in the absence of punishment possibilities. Variation in wealth is substantial with the richest groups earning more than ten times what the poorest groups earn. Introducing the possibility of punishment does not increase wealth and in some cases even decreases it. In the presence of a punishment option inequality in early periods is strongly negatively correlated with group income in later periods, highlighting negative interaction effects between endogenous inequality and punishment. </p> https://www.elias-tsakas.com/research/misreporting/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/misreporting/ <div class="tc"> <p><a href="https://www.elias-tsakas.com/papers/Misreporting.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>It is well-known that subjective beliefs cannot be identified with traditional choice data unless we impose the strong assumption that preferences are state-independent. This is seen as one of the biggest pitfalls of incentivized belief elicitation. The two common approaches are either to exogenously assume that preferences are state-independent, or to use intractable elicitation mechanisms that require an awful lot of hard-to-get non-traditional choice data. In this paper we use a third approach, introducing a novel methodology that retains the simplicity of standard elicitation mechanisms without imposing the awkward state-independence assumption. The cost is that instead of insisting on full identification of beliefs, we seek identification of misreporting. That is, we elicit beliefs with a standard simple elicitation mechanism, and then by means of a single additional observation we can tell whether the reported beliefs deviate from the actual beliefs, and if so, in which direction they do.</p> https://www.elias-tsakas.com/research/limitedfocus/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/limitedfocus/ <div class="tc"> <p class="f3"><strong><em>International Journal of Game Theory</em></strong></p> <p>(with <a href="https://www.epicenter.name/Perea/">Andres Perea</a>)</p> <p><a href="https://link.springer.com/article/10.1007/s00182-018-0642-x">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/LocalFI.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In this paper we introduce a novel framework that allows us to model games with players who disregard part of the game tree, thus reasoning about their opponents' rationality at some histories only. Our primary interest is to understand the behavioral implications of the players' failure to focus on some parts of the game tree. Indeed, we characterize the strategy profiles that can be rationally played if players try to rationalize their opponents' moves only at the histories they focus on. We also present several special cases and applications of our framework. </p> https://www.elias-tsakas.com/research/noisypersuasion/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/noisypersuasion/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p>(with <a href="https://sites.google.com/site/nikolastsakas/">Nikolas Tsakas</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/NoisyPersuasionGEB.pdf">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/NoisyPersuasion.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We study the effect of noise due to exogenous information distortions in the context of Bayesian persuasion. In particular, we first provide a full characterization of the optimal signal in a standard special case that has attracted a lot of attention in the literature. Then, we ask whether more noise (a la Blackwell) is always harmful for the information designer, i.e., the sender. We show that in general this is not the case. We provide a necessary and sufficient condition for the sender to always be worse off when noise increases in a binary noisy channel. There are two ways to read our result: (a) the sender always dislikes additional noise if and only if we start with little noise in the first place, (b) the sender always dislikes additional noise if and only if this additional noise is modelled by a sufficiently symmetric channel. Then, we provide sufficient conditions that extend this result to channels of arbitrary cardinality. Finally, we show that in every noisy persuasion game, increased complexity of the message space makes the sender weakly better off, while for a rather rich class of games the improvement is strict. This is in contrast to the noiseless case, where the sender’s maximum expected utility can always be achieved with a bounded number of messages.</p> https://www.elias-tsakas.com/research/obviousbeliefelicitation/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/obviousbeliefelicitation/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0899825619300983">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/ObviousElicitation.pdf">Working paper</a> </p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>An investigator is interested in arbitrarily approximating a subject’s latent beliefs in obviously dominant strategies (Li, 2017). We prove that Karni’s ascending mechanism (Karni, 2009) does not have an obviously dominant strategy. Thus, we introduce the novel descending Karni mechanism which always has obviously dominant strategies. Furthermore, under the assumption that the subject chooses an obviously dominant strategy, the true beliefs can be approximated with arbitrary precision with our mechanism. All our results hold for a very broad class of likelihood relations, going well beyond those that are represented by probabilistic beliefs. </p> https://www.elias-tsakas.com/research/agreementcommunication/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/agreementcommunication/ <div class="tc"> <p class="f3"><strong><em>Journal of Mathematical Economics</em></strong></p> <p>(with <a href="https://www.hhs.se/en/persons/v/voorneveld-mark/">Mark Voorneveld</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S030440681100111X">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/ConsensusJME.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/ConsensusPresentation.pdf">Presentation</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>The present paper extends the standard model of pairwise communication among Bayesian agents to cases where the structure of the communication protocol is not commonly known. We show that, even under standard strict conditions on the structure of the protocols and the nature of the transmitted signals, a consensus may never be reached if very little asymmetric information about the protocol is introduced.</p> https://www.elias-tsakas.com/research/pairwiserationalizability/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/pairwiserationalizability/ <div class="tc"> <p class="f3"><strong><em>Mathematical Social Sciences</em></strong></p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0165489613000747">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/PairwiseRationalizabilityMSS.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We provide a foundation for correlated rationalizability by means of pairwise epistemic conditions imposed only on some pairs of players. Indeed, we show that pairwise mutual belief, for some pairs of players, of (i) the game payoffs, (ii) rationality, and (iii) deeming possible only strategy profiles that receive positive probability by the actual conjectures suffice for correlated rationalizability when there is a common prior. Moreover, we show that our epistemic conditions do not require nor imply mutual belief of rationality. Finally, we discuss the relationship between correlated rationalizability and Nash equilibrium on the basis of the respective pairwise epistemic conditions for each of the two concepts.</p> https://www.elias-tsakas.com/research/pairwisene/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/pairwisene/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p>(with <a href="https://www.epicenter.name/bach/">Christian Bach</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0899825614000220">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/PairwiseNE.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/PairwiseNEPres.pdf">Presentation</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We introduce a framework for modeling pairwise interactive beliefs and provide an epistemic foundation for Nash equilibrium in terms of pairwise epistemic conditions locally imposed on only some pairs of players. Our main result considerably weakens not only the standard sufficient conditions by Aumann and Brandenburger (1995), but also the subsequent generalization by Barelli (2009). Surprisingly, our conditions do not require nor imply mutual belief in rationality.</p> https://www.elias-tsakas.com/research/pastexperienceuncertainty/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/pastexperienceuncertainty/ <div class="tc"> <p class="f3"><strong><em>Experimental Economics</em></strong></p> <p>(with <a href="https://sites.google.com/site/friederikemengel/">Friederike Mengel</a> and <a href="https://www.vostroknutov.com">Alexander Vostroknutov</a>)</p> <p><a href="https://link.springer.com/article/10.1007/s10683-015-9431-6">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/AwarExp.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/AwarExpSuppl.pdf">Supplementary material</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In an experiment with more than 500 participants we study how past experience of uncertainty (imperfect knowledge of the state space) affects risk preferences. Participants in our experiment choose between a sure outcome and a lottery in 32 periods. All treatments are exactly identical in periods 17 to 32 but differ in periods 1 to 16. In the early periods of the Risk Treatment there is perfect information about the lottery; in the Ambiguity Treatment participants perfectly know the outcome space but not the associated probabilities; in the Unawareness Treatment participants have imperfect knowledge about both outcomes and probabilities. We observe strong treatment effects on behavior in periods 17 to 32. In particular, participants who have been exposed to an environment with very imperfect knowledge of the state space subsequently choose lotteries with high (low) variance less (more) often compared to other participants. Estimating individual risk attitudes from choices in periods 17 to 32 we find that the distribution of risk attitude parameters across our treatments can be ranked in terms of first order stochastic dominance. Our results show how exposure to environments with different degrees of uncertainty can affect individuals' subsequent risk-taking behavior.</p> https://www.elias-tsakas.com/research/procuringunverifiableinformation/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/procuringunverifiableinformation/ <div class="tc"> <p class="f3"><strong><em>Mathematics of Operations Research</em></strong></p> <p>(with <a href="https://sites.google.com/view/salilsharma/salil-sharma">Salil Sharma</a> and <a href="https://www.hhs.se/en/persons/v/voorneveld-mark/">Mark Voorneveld</a>)</p> <p><a href="https://pubsonline.informs.org/doi/abs/10.1287/moor.2022.0085?journalCode=moor">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/PriceInformation.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We study settings where information in the form of Bayesian signals is acquired by an expert on behalf of a principal. Information acquisition is costly for the expert, and crucially not verifiable by the principal. The expert is compensated by the principal with a menu of state-contingent payments. We provide a full characterization of the set of all menus that implement (resp., strictly implement) each signal. Moreover, we provide a closed-form characterization for the expected cost for the cheapest such menu, which we call proxy cost of the signal. Surprisingly, in general, the proxy cost is neither increasing in the Blackwell order, nor posterior-separable, even when the expert’s cost function is posterior-separable itself. Subsequently, we study the full agency problem (by introducing a downstream decision), thus endogenizing the signal. We show that there is always an optimal signal that can be strictly implemented, meaning that it is without loss of generality to exogenously restrict attention to strict implementation. As a result, similarly to Bayesian persuasion, the complexity of the principal’s optimal signal is bounded by the cardinality of the state space. Finally, we present some applications of interest. </p> https://www.elias-tsakas.com/research/rationalbeliefhierarchies/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/rationalbeliefhierarchies/ <div class="tc"> <p class="f3"><strong><em>Journal of Mathematical Economics</em></strong></p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0304406813000979">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/RationalBeliefsJME.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We consider agents who attach a rational probability to every Borel event. We call these Borel probability measures rational, and introduce the notion of a rational belief hierarchy, where the first order beliefs are described by a rational measure over the fundamental space of uncertainty, the second order beliefs are described by a rational measure over the product of the fundamental space of uncertainty and the opponent's first order rational beliefs, and so on. Then, we derive the corresponding rational type space model, thus providing a Bayesian representation of rational belief hierarchies. Our main result shows that this type-based representation has the counterintuitive property that some rational types are associated with non-rational beliefs over the product of the fundamental space of uncertainty and the opponent's types, thus implying that the agent may attach an irrational probability to some Borel event even if she has a rational belief hierarchy.</p> https://www.elias-tsakas.com/research/guessinggames/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/guessinggames/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p>(with <a href="https://sites.google.com/view/christianseel">Christian Seel</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0899825617301689?_docanchor=&_fmt=high&_origin=gateway&_rdoc=1&md5=b8429449ccfc9c30159a5f9aeaa92ffb">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/Guessing.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Games in which players aim to guess a fraction or multiple \(p\) of the average guess are known as guessing games or \(p\)-beauty contests. In this note, we derive a full characterization of the set of rationalizable strategies and the set of pure strategy Nash equilibria for such games as a function of the parameter \(p\), the number of players and the (discrete) set of available guesses to each player.</p> https://www.elias-tsakas.com/research/reasonabledoubt/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/reasonabledoubt/ <div class="tc"> <p><a href="https://www.elias-tsakas.com/papers/ReasonableDoubt.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/SlidesReasonableDoubt.pdf">Presentation</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Choice rules based on probability thresholds are common in several disciplines. The most well-known application of such a threshold rule is the standard of reasonable doubt. Accordingly, a rational juror prefers to convict a defendant if and only if the probability that she attaches to the defendant being guilty is above a given threshold. In this paper we prove that generically such a threshold exists if and only if the juror reasons only about two events, viz., the defendant's guilt and innocence. This result implies that threshold rules are usually inconsistent with individual rationality. Thus, if we insist on using a threshold choice rule, we will have to accept some irrational convictions (false negatives) or some irrational acquittals (false positives) or both. We subsequently characterize each probability threshold in terms of the irrationalities that it induces. Finally, we discuss the empirical implications of our theory.</p> https://www.elias-tsakas.com/research/reasoningbasedintrospection/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/reasoningbasedintrospection/ <div class="tc"> <p class="f3"><strong><em>Theory and Decision</em></strong></p> <p>(with <a href="http://gossner.me">Olivier Gossner</a>)</p> <p><a href="https://link.springer.com/article/10.1007/s11238-011-9284-1">Journal publication</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We show that if an agent reasons according to standard inference rules, the truth and introspection axioms extend from the set of non-epistemic propositions to the whole set of propositions. This implies that the usual axiomatization of partitional possibility correspondences is redundant, and provides a justification for truth and introspection that is partly based on reasoning.</p> </div> https://www.elias-tsakas.com/research/regulatinginformation/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/regulatinginformation/ <div class="tc"> <p>(with <a href="https://www.pgonzalezfernandez.com">Pedro Gonzalez-Fernandez</a> and <a href="https://sites.google.com/site/stefanterstiege/home">Stefan Terstiege</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/RegulatingInformation.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Economic agents often seek to acquire information before taking an important action, but in many domains, gathering this information requires approval from a regulator. This paper develops a model in which an agent designs an experiment to inform his decision, but can only implement it if a regulator authorizes it ex ante. We characterize the agent's optimal experiment under this approval constraint and show that, whenever the regulator rejects full revelation, the agent strategically reduces informativeness in the states where their disagreement is least sensitive. We then extend the model to settings with multiple regulators, comparing sequential and collective approval mechanisms. The analysis yields predictions for how institutional structure shapes access to information, with applications to clinical trials, data privacy, and ethics boards.</p> https://www.elias-tsakas.com/research/resistingpersuasion/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/resistingpersuasion/ <div class="tc"> <p class="f3"><strong><em>Economic Theory</em></strong></p> <p>(with <a href="https://link.springer.com/article/10.1007/s00199-020-01339-0">Nikolas Tsakas</a> and <a href="https://sites.google.com/site/dxefteris/">Dimitrios Xefteris</a>)</p> <p><a href="https://www.elias-tsakas.com/files/paper.pdf">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/ResistingPersuasion.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In the context of Bayesian Persuasion (Kamenica and Gentzkow, 2011), typically, a biased Sender designs a signal to influence the binary decision of an unbiased Receiver. Can the Re- ceiver improve her payoffs by adopting a resistance strategy, i.e., by committing into incurring (deterministic or stochastic) costs if she picks the Sender-preferred action? We argue that deter- ministic resistance strategies cannot improve the Receiver’s payoffs, whereas stochastic resistance strategies can increase both the informativeness of the signal and the Receiver’s payoffs. We fully characterize the optimal resistance strategy and show that it always induces a substantial increase in the Receiver’s welfare, as well as a perfectly informative signal.</p> https://www.elias-tsakas.com/research/robustscoringrules/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/robustscoringrules/ <div class="tc"> <p class="f3"><strong><em>Theoretical Economics</em></strong></p> <p><a href="https://econtheory.org/ojs/index.php/te/article/viewArticle/3557">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/ScoringRules.pdf">Working paper</a> / <a href="https://www.elias-tsakas.com/papers/ScoringRules2.pdf">Working paper (older version)</a> / <a href="https://www.elias-tsakas.com/papers/SlidesScoringRules.pdf">Presentation</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Is it possible to guarantee that the mere exposure of a subject to a belief elicitation task will not affect the very same beliefs that we are trying to elicit? In this paper, we introduce mechanisms that make it simultaneously strictly dominant for the subject (a) not to acquire any information that could potentially lead to belief updating as a response to the incentives provided by the mechanism itself, and (b) to report his beliefs truthfully. Such mechanisms are called robust scoring rules. We prove that robust scoring rules always exist under mild assumptions on the subject's costs for acquiring information. Moreover, every scoring rule can become approximately robust, in the sense that if we scale down the incentives sufficiently, we will approximate with arbitrary precision the beliefs that the subject would have held if he had not been confronted with the belief-elicitation task. </p> https://www.elias-tsakas.com/research/sequentialsearch/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/sequentialsearch/ <div class="tc"> <p>(with <a href="https://www.pilinov.com">Pavel Ilinov</a>, <a href="https://sites.google.com/view/andreimatveenko/home">Andrei Matveenko</a>, <a href="https://sites.google.com/view/salilsharma/salil-sharma">Salil Sharma</a> and <a href="https://www.hhs.se/en/persons/v/voorneveld-mark/">Mark Voorneveld</a>)</p> <p><a href="https://www.elias-tsakas.com/papers/ScreeningCandidates.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Economic agents often seek to acquire information before taking an important action, but in many domains, gathering this information requires approval from a regulator. This paper develops a model in which an agent designs an experiment to inform his decision, but can only implement it if a regulator authorizes it ex ante. We characterize the agent's optimal experiment under this approval constraint and show that, whenever the regulator rejects full revelation, the agent strategically reduces informativeness in the states where their disagreement is least sensitive. We then extend the model to settings with multiple regulators, comparing sequential and collective approval mechanisms. The analysis yields predictions for how institutional structure shapes access to information, with applications to clinical trials, data privacy, and ethics boards.</p> https://www.elias-tsakas.com/research/targetprojection/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/targetprojection/ <div class="tc"> <p class="f3"><strong><em>Games and Economic Behavior</em></strong></p> <p>(with <a href="https://www.hhs.se/en/persons/v/voorneveld-mark/">Mark Voorneveld</a>)</p> <p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0899825609000141">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/ProjectionDynamicGEB.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>We study the target projection dynamic, a model of learning in normal form games. The dynamic is given a microeconomic foundation in terms of myopic optimization under control costs due to a certain status-quo bias. We establish a number of desirable properties of the dynamic: existence, uniqueness and continuity of solution trajectories, Nash stationarity, positive correlation with payoffs, and innovation. Sufficient conditions are provided under which strictly dominated strategies are wiped out. Finally some stability results are provided for special classes of games.</p> https://www.elias-tsakas.com/research/motivatedbeliefsfmri/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/motivatedbeliefsfmri/ <div class="tc"> <p class="f3"><strong><em>Social Cognitive and Affective Neuroscience</em></strong></p> <p>(with <a href="https://scholar.google.com/citations?user=DZlLAN0AAAAJ&hl=el">Giannis Lois</a>, <a href="https://scholar.google.com/citations?user=QEuNykgAAAAJ&hl=en">Kenneth Yuen</a> and <a href="https://www.arnoriedl.com">Arno Riedl</a>)</p> <p><a href="https://academic.oup.com/scan/article/19/1/nsae056/7738142?login=false">Journal publication</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>Susceptibility to misinformation and belief polarization often reflect people's tendency to incorporate information in a biased way. Despite the presence of competing theoretical models, the underlying neurocognitive mechanisms of motivated reasoning remain elusive as previous empirical work did not properly track the belief formation process. To address this problem, we employed a design that identifies motivated reasoning as directional deviations from a Bayesian benchmark of unbiased belief updating. We asked members of a pro-immigration or an anti-immigration group how much they endorse factual messages on foreign criminality, a polarizing political topic. Both groups exhibited a desirability bias by over-endorsing attitude-consistent messages and under-endorsing attitude-discrepant messages and an identity bias by over-endorsing messages from ingroup members and under-endorsing messages from outgroup members. In both groups, neural responses to the messages predicted subsequent expression of desirability and identity biases suggesting a common neural basis of motivated reasoning across ideologically opposing groups. Specifically, brain regions implicated in encoding value, error detection, and mentalizing tracked the degree of desirability bias. Less extensive activation in the mentalizing network tracked the degree of identity bias. These findings illustrate the distinct neurocognitive architecture of desirability and identity biases and inform existing cognitive models of politically motivated reasoning.</p> https://www.elias-tsakas.com/research/universallyrationalbeliefhierarchies/ Sat, 16 May 2026 15:11:34 +0200 https://www.elias-tsakas.com/research/universallyrationalbeliefhierarchies/ <div class="tc"> <p class="f3"><strong><em>International Game Theory Review</em></strong></p> <p><a href="https://www.worldscientific.com/doi/abs/10.1142/S0219198914400039">Journal publication</a> / <a href="https://www.elias-tsakas.com/papers/UnivRationalBeliefsIGTR.pdf">Working paper</a></p> <p><strong>Abstract.</strong></p> </div> <div class="tj"> <p>In a recent paper, Tsakas (2012) introduced the notion of rational beliefs. These are Borel probability measures that assign a rational probability to every Borel event. Then, he constructed the corresponding Harsanyi type space model that represents the rational belief hierarchies. As he showed, there are rational types that are associated with a non-rational probability measure over the product of the underlying space of uncertainty and the opponent's types. In this paper, we define the universally rational belief hierarchies, as those that do not exhibit this property. Then, we characterize them in terms of a natural restriction imposed directly on the belief hierarchies.</p>