I am an economist who combines theory and laboratory experiments to study how
institutions shape collective decisions. Much of my work asks how voting rules aggregate
voters' information and preferences, when they fail, and how people actually behave when
those rules are taken to the laboratory.
I received my PhD from Universitat Pompeu Fabra in 2008. Before joining Queen Mary in
2013, I was a postdoctoral scholar at Caltech and then a research fellow at the Max Planck
Institute for Research on Collective Goods in Bonn.
Publications
with Santiago Oliveros and Ro'i Zultan
Management Science, forthcoming
We study demand for symmetric and asymmetric information sources in the laboratory. Although participants respond to incentives and instrumental considerations, they exhibit a systematic bias towards symmetric sources. These patterns persist among individuals with higher cognitive abilities and better task comprehension, and they are not accounted for by their elicited subjective beliefs.
with Laurent Bouton, Antonin Macé and Dimitrios Xefteris
Journal of the European Economic Association, 2024, 22(6), 2598–2647
This paper examines the comparative properties of voting rules based on the richness of their ballot spaces, assuming a given distribution of voting rights. We focus on how well voting rules aggregate the information dispersed among voters. We consider how different voting rules affect both voters’ decisions at the voting stage and the incentives of the agenda-setter, who decides whether to put the proposal to a vote. Without agenda-setter, the voting efficiency of rules is higher when their ballot space is richer. Moreover, full-information efficiency requires full divisibility of the votes. In the presence of an agenda-setter, we uncover a novel trade-off: in some cases, rules with high voting efficiency provide worse incentives to the agenda-setter to select good proposals. This negative effect can be large enough to wash out the higher voting efficiency of even the most efficient rules.
with Roman Sheremeta and Nora Szech
European Economic Review, 2023, 154, 104327
A well-known theoretical result in the contest literature is that greater heterogeneity decreases investments of contestants because of the “discouragement effect.” Levelling the playing field by favouring weaker contestants through strict bid-caps and favourable tie-breaking rules can reduce discouragement and increase the designer's revenue. We test these predictions in a laboratory experiment. Our data confirm that placing bid-caps and using favourable tie-breaking rules significantly diminishes discouragement of weaker contestants. However, its impact on revenues is muted by the fact that the encouragement of weaker contestants is offset by stronger contestants competing less aggressively, even when not predicted by theory. We discuss deviations from the Nash predictions in light of different behavioural approaches.
with Laurent Bouton, Jorge Gallego and Rebecca Morton
Economic Journal, 2022, 132(641), 106–146
We study experimentally the properties of the majority run-off system and compare them to those of plurality rule. Our focus is on Duverger’s famous prediction that the plurality rule leads to higher co-ordination of votes on a limited number of candidates than the majority run-off rule. We find strong co-ordination forces under both systems. However, as predicted by the theory, in some cases these forces are stronger under plurality. Despite these differences in voting behaviour, we find small and mostly not significant differences in electoral outcomes and, hence, voters’ welfare.
with Helios Herrera and Joseph McMurray
Journal of Public Economics, 2019, 179, 104051
This paper documents a laboratory experiment that analyzes voter participation in common interest proportional representation (PR) elections, comparing this with majority rule. Consistent with theoretical predictions, poorly informed voters in either system abstain from voting, thereby shifting weight to those who are better informed. A dilution problem makes mistakes especially costly under PR, so abstention is higher in PR in contrast with private interest environments, and welfare is lower. Deviations from Nash equilibrium predictions can be accommodated by a logit version of quantal response equilibrium (QRE), which allows for voter mistakes.
with Helios Herrera and Joseph McMurray
Economic Journal, 2019, 129(624), 3137–3153
The swing voter’s curse is useful for explaining patterns of voter participation, but arises because voters restrict attention to the rare event of a pivotal vote. Recent empirical evidence suggests that electoral margins influence policy outcomes, even away from the 50% threshold. If so, voters should also pay attention to the marginal impact of a vote. Adopting this assumption, we find that a marginal voter’s curse gives voters a new reason to abstain: to avoid diluting the pool of information. The two curses have similar origins and exhibit similar patterns, but the marginal voter’s curse is both stronger and more robust. In fact, the swing voter’s curse turns out to be on a knife edge: in large elections, a model with both pivotal and marginal considerations and a model with marginal considerations alone generate identical equilibrium behaviour.
with Dietmar Fehr and Frank Heinemann
Journal of Monetary Economics, 2019, 103, 123–136
In an experiment using a coordination game with extrinsic random signals (“sunspots”), we systematically vary the stochastic process generating these signals and measure how signals affect behavior. We find that sunspot equilibria emerge naturally with salient public signals. However, highly correlated private signals can also lead to sunspot-driven behavior, even when this is not an equilibrium. Private signals reduce the power of public signals as sunspot variables. The higher the correlation of extrinsic signals and the more easily they can be aggregated, the more powerful these signals are in distracting actions from the action that minimizes strategic uncertainty.
with Laurent Bouton and Frédéric Malherbe
Journal of Political Economy, 2018, 126(1), 107–149
We study unanimous decision making under incomplete information. We argue that unanimous decision rules are not all equivalent. We show that majority rules with veto power are (i) Pareto superior to commonly used unanimous rules and (ii) ex ante efficient in a broad class of situations.
with Jon Eguia, Rebecca Morton and Antonio Nicolò
Games and Economic Behavior, 2018, 109, 465–483
Games with imperfect information often feature multiple equilibria, which depend on beliefs off the equilibrium path. Standard selection criteria such as passive, symmetric or wary beliefs rest on ad hoc restrictions on beliefs. We propose a new selection criterion that imposes no restrictions on beliefs: we select the action profile that is supported in equilibrium by the largest set of beliefs. We conduct an experiment to compare the predictive power of the existing and our novel selection criteria in an application on vertical multi-lateral contracting. We find that our criterion outperforms the other selection criteria.
with Ro'i Zultan
European Economic Review, 2017, 95, 84–102
The theoretical literature on collusion in auctions suggests that the first-price mechanism can deter the formation of bidding rings. However, such analyses neglect to consider the effects of failed collusion attempts, wherein information revealed in the negotiation process may affect bidding behaviour. We experimentally test a setup in which theory predicts no collusion and no information revelation in first-price auctions. The results reveal a hitherto overlooked failing of the first-price mechanism: failed collusion attempts distort bidding behaviour, resulting in a loss of seller revenue and efficiency. Moreover, the first-price mechanism does not result in less collusion than the second-price mechanism. We conclude that, while the features of the first-price mechanism may have the potential to deter bidder collusion, the role of beliefs in guiding bidding behaviour make it highly susceptible to distortions arising from the informational properties of collusive negotiation. Auction designers should take this phenomenon into account when choosing the auction mechanism.
with Laurent Bouton and Frédéric Malherbe
Games and Economic Behavior, 2017, 102, 179–198
We study the information aggregation properties of unanimous voting rules in the laboratory. In line with theoretical predictions, we find that majority rule with veto power dominates unanimity rule. We also find that the strategic voting model is a fairly good predictor of subject behavior. Finally, we exploit a framing effect to study how the presence of less sophisticated agents affects Veto's welfare properties.
with Laurent Bouton and Micael Castanheira
Games and Economic Behavior, 2017, 101, 132–150
The rational-voter model is often criticized on the grounds that two of its central predictions (the paradox of voting and Duverger's Law) are at odds with reality. Recent theoretical advances suggest that these empirically unsound predictions might be an artifact of an (arguably unrealistic) assumption: the absence of aggregate uncertainty about the distribution of preferences in the electorate. In this paper, we propose direct empirical evidence of the effects of aggregate uncertainty in multicandidate elections. Adopting a theory-based experimental approach, we explore whether aggregate uncertainty indeed favors the emergence of non-Duverger's law equilibria in plurality elections. Our experimental results support the main theoretical predictions.
with Emanuel Towfigh, Sebastian J. Goerg, Andreas Glöckner, Philip Leifeld, Sophie Bade and Carlos Kurschilgen
Public Choice, 2016, 167, 47–65
Are direct-democratic decisions more acceptable to voters than decisions arrived at through representative procedures? We conduct an experimental online vignette study with a German sample to investigate how voters’ acceptance of a political decision depends on the process through which it is reached. For a set of different issues, we investigate how acceptance varies depending on whether the decision is the result of a direct-democratic institution, a party in a representative democracy, or an expert committee. Our results show that for important issues, direct democracy generates greater acceptance; this finding holds particularly for those voters who do not agree with a collectively chosen outcome. However, if the topic is of limited importance to the voters, acceptance does not differ between the mechanisms. Our results imply that a combination of representative democracy and direct democracy, conditional on the distribution of issue importance among the electorate, may be optimal with regard to acceptance of political decisions.
with Laurent Bouton and Micael Castanheira
Journal of Public Economics, 2016, 134, 114–128
We propose a theory-based experimental approach to compare the properties of approval voting (AV) with those of plurality. This comparison is motivated by the theoretical prediction that, in our aggregate uncertainty setup, AV should produce close to first-best outcomes, while plurality will not. The experiment shows, first, that welfare gains are substantial. Second, both aggregate and individual responses are in line with theoretical predictions, and thus with strategic voting. Finally, subjects' behavior under AV highlights the need to study equilibria in asymmetric strategies.
with Rafael Hortala-Vallve and Rosemarie Nagel
Experimental Economics, 2013, 16, 88–113
We analyze a bargaining protocol recently proposed in the literature vis-à-vis unconstrained negotiation. This new mechanism extracts “gains from trade” inherent in the differing valuation of two parties towards various issues where conflict exists. We assess the role of incomplete vs. complete information in the efficiency achieved by this new mechanism and by unconstrained negotiation. We find that unconstrained negotiation does best under a situation of complete information where the valuations of both bargaining parties are common knowledge. Instead, the newly proposed mechanism does best in a situation with incomplete information. The sources of inefficiencies in each of the two cases arise from the different strategic use of the available information.
with Alessandra Casella and Thomas R. Palfrey
Journal of Political Economy, 2012, 120(4), 593–658
We develop a competitive equilibrium theory of a market for votes. Before voting on a binary issue, individuals may buy and sell their votes with each other. We define the concept of ex ante vote-trading equilibrium and show by construction that an equilibrium exists. The equilibrium we characterize always results in dictatorship if there is any trade, and the market for votes generates welfare losses, relative to simple majority voting, if the committee is large enough or the distribution of values is not very skewed. We test the theoretical implications in the laboratory using a continuous open-book multiunit double auction.
with Rafael Hortala-Vallve
International Journal of Game Theory, 2012, 41, 331–343
We analyze a Colonel Blotto game in which opposing parties have differing relative intensities. In other words, the game is non-zero sum because colonels have asymmetric and heterogeneous battlefield valuations. We characterize the colonels’ payoffs that sustain a pure strategy equilibrium and present an algorithm that reaches the equilibrium actions (when they exist). Finally we show that the set of games with a pure strategy equilibria is non-empty.
with Rafael Hortala-Vallve
Games and Economic Behavior, 2010, 70(2), 375–391
In Conflict Resolution situations where two parties with opposed preferences need to make a number of decisions simultaneously, we propose a simple mechanism that endows agents with a certain number of votes that can be distributed freely across issues. This mechanism allows parties to trade off their voting power across issues and extract gains from differences in the intensities of their preferences. The appealing properties of such a mechanism may be negated by strategic interactions among individuals. We test its properties using controlled laboratory experiments. We observe that equilibrium play increases over time and truthful/honest play decreases over time. The subjects almost reach the welfare predicted by the theory even when their behaviour is far from equilibrium. The fact that deviations from equilibrium do not do much damage to its welfare properties is a further argument in favour of the use of this mechanism in the real world.