Publications des chercheurs de PSE

Internet is a very attractive technology for the implementation of experiments, both in order to obtain larger and more diverse samples and as a field of economic research in its own right. This paper reports on an experiment performed both online and in the laboratory, designed to strengthen the internal validity of decisions elicited over the Internet. We use the same subject pool, the same monetary stakes and the same decision interface, and control the assignment of subjects between the Internet and a traditional university laboratory. We apply the comparison to the elicitation of social preferences in a Public Good game, a dictator game, an ultimatum bargaining game and a trust game, coupled with an elicitation of risk aversion. This comparison concludes in favor of the reliability of behaviors elicited through the Internet. We moreover find a strong overall parallelism in the preferences elicited in the two settings. The paper also reports some quantitative differences in the point estimates, which always go in the direction of more other-regarding decisions from online subjects. This observation challenges either the predictions of social distance theory or the generally assumed increased social distance in internet interactions.

This study explores whether an oath to honesty can reduce both shirking and lying among crowd-sourced internet workers. Using a classic coin-flip experiment, we first confirm that a substantial majority of Mechanical Turk workers both shirk and lie when reporting the number of heads flipped. We then demonstrate that lying can be reduced by first asking each worker to swear voluntarily on his or her honor to tell the truth in subsequent economic decisions. Even in this online, purely anonymous environment, the oath significantly reduced the percent of subjects telling “big” lies (by roughly 27%), but did not affect shirking. We also explore whether a truth-telling oath can be used as a screening device if implemented after decisions have been made. Conditional on flipping response, MTurk shirkers and workers who lied were significantly less likely to agree to an ex-post honesty oath. Our results suggest oaths may help elicit more truthful behavior, even in online crowd-sourced environments

The fact that home football teams win more games than away teams has been largely discussed in the literature. Crowd factors appear to be the most dominant cause of this home advantage . At the end of the 2019–2020 season, the COVID-19 pandemic forced European football teams to close their stadium to fans, allowing researchers to exploit this natural experiment to analyze the effects of crowd on match outcomes and referees' decisions. To answer to this question, we used match data played in the top two divisions of four of the main national professional leagues in European countries and Portugal in the 2018–19 and the 2019–20 seasons. We find that the total absence of a generally supportive crowd has a significant effect on home advantage. This results in a reduction of the chances of a home win, a poorer performance by the home team's players, and more severe refereeing decisions toward the home team and less severe toward the away team.

We report in this paper the result of three experiments on risk, ambiguity and time attitude. The first two differed by the population considered (students vs. general population) while the third one used a different protocol and concerned students and portfolio managers. We find quite a lot of heterogeneity at the individual level. Of principal interest was the elicitation of risk, time and ambiguity attitudes and the relationship among these (model free) measures. We find that on the student population, there is essentially no correlation. A non negligible fraction of the population behaves in an extremely cautious manner in the risk and ambiguity domain. When we drop this population from the sample, the correlation between our measures is also non significant. We also raise three questions linked to measurement of ambiguity attitudes that come out from our data sets.

Internet is a very attractive technology for the implementation of experiments, both in order to obtain larger and more diverse samples and as a field of economic research in its own right. This paper reports on an experiment performed both online and in the laboratory, designed to strengthen the internal validity of decisions elicited over the Internet. We use the same subject pool, the same monetary stakes and the same decision interface, and control the assignment of subjects between the Internet and a traditional university laboratory. We apply the comparison to the elicitation of social preferences in a Public Good game, a dictator game, an ultimatum bargaining game and a trust game, coupled with an elicitation of risk aversion. This comparison concludes in favor of the reliability of behaviors elicited through the Internet. We moreover find a strong overall parallelism in the preferences elicited in the two settings. The paper also reports some quantitative differences in the point estimates, which always go in the direction of more other-regarding decisions from online subjects. This observation challenges either the predictions of social distance theory or the generally assumed increased social distance in internet interactions.

In theory, voter attitudes towards policy changes (e.g., whether to increase the minimum wage) ought to depend on their beliefs about the current level of the relevant policy variable. In this paper, I test this hypothesis using a large-scale (n = 5, 000) and pre-registered survey experiment that spans four different policy areas. The experiment yields four main results. First, voters have both inaccurate and biased beliefs about the levels of the policy variables. Second, voters’ attitudes are remarkably unresponsive to changes in their beliefs about levels: for example, exogenously increasing average beliefs about the top tax rate by ∼8.5 percentage points does not increase the share who want to cut the top tax rate. Third, the observed unresponsiveness cannot be rationalised by a model in which voters form attitudes towards policy changes by comparing actual and preferred policy levels. Fourth, although attitudes are unresponsive to the quantitative information presented, they can be swayed by qualitative arguments.

There are many important decision problems where learning through experimentation is costly or impossible. In these situations, individuals may try to learn from observing the outcomes of others who have made similar decisions. Often, however, information about others comprises a selected dataset, as outcomes are observed conditional on specific choices having been made. In this paper, we design an investment game which allows us to study the influence of selection when learning from others. Using the theoretical study of selection neglect in Jehiel (2018) as a guide, we test (i) for the presence of selection neglect in this investment context, and (ii) some comparative static predictions of the model. We find strong evidence for selection neglect-even though subjects are fully informed about the data generating process. As theoretically predicted, the degree of bias due to selection neglect increases when other decision makers become more informed, or become more rational. It decreases when signals are correlated.

We study the choice of multi-person bargaining protocols in the context of politics. In politics, citizens are increasingly involved in the design of democratic rules, for instance via referendums. If they support the rule that best serves their self-interest, the outcome inevitably advantages the largest group. In this paper, we challenge this pessimistic view with an original lab experiment, in which 252 subjects participated. In the first stage, these subjects experience elections under plurality and approval voting. In the second stage, they decide which rule they want to use for extra elections. We find that egalitarian values that subjects hold outside of the lab shape their choice of electoral rule in the second stage when a rule led to a fairer distribution of payoffs compared to the other one in the first stage. The implication is that people have consistent ‘value-driven preferences’ for decision rules.

This study explores selection neglect in an experimental investment game where individuals can learn from others' outcomes. Experiment 1 examines aggregate-level equilibrium behavior. We find strong evidence of selection neglect and corroborate several comparative static predictions of Jehiel's (2018) model, showing that the severity of the bias is aggravated by the sophistication of other individuals and moderated when information is more correlated across individuals. Experiment 2 focuses on individual decision-making, isolating the influence of beliefs from possible confounding factors. This allows us to classify individuals according to their degree of naivety and explore the limits of, and potential remedies for, selection neglect.

In this paper, we design and implement an experiment aimed at testing the level-k model of auctions. We begin by identifying (simple) environments that optimally disentangle the predictions of the level-k model from the natural benchmark of Bayes-Nash equilibrium. We then implement these environments within a virtual laboratory in order to see which theory can best explain observed bidding behaviour. Overall, our findings suggest that, despite its notable success in predicting behaviour in other strategic settings, the level-k model (and its close cousin, cognitive hierarchy) cannot explain behaviour in auctions.