ECONOMIE COMPORTEMENTALE

Abstract: Policies addressing physician shortages typically target aggregate supply, yet the composition of the local workforce may also determine which health needs get met. I study a program that periodically sends a visiting female general practitioner (GP) to rural Australian towns where all resident physicians are male, comparing each woman's consultations with the visiting GP to her own consultations with local male providers. The same woman is roughly four times as likely to receive genitourinary or hormonal prescriptions when consulting the female GP, against a baseline of 6 percent, and more than ten times as likely to be screened for cervical cancer, against a baseline of 1 percent. Consultations with the female GP are also nearly four times as likely to be long, while placebo visits to other male providers generate no comparable response. Complementary difference-in-differences estimates, which exploit variation in when the program began across towns, show that prescribing effects are concentrated among program users. The pattern is consistent with women raising hormonal and gynaecological concerns with the female GP that they are less likely to raise with local male providers.

Abstract: The paper analyzes the theoretical effect of risk aversion on the demand for vaccines that reduce the severity of a disease but are also perceived as presenting a risk of side effects. Risk aversion is first shown to have ambiguous effect on the propensity to vaccinate. However, the model highlights how this relationship is influenced by the characteristics of the vaccine’s side effects. Namely, risk averse individuals are more prone to get vaccinated than risk neutral ones when the side effects potentially induced by the vaccine are relatively likely but not severe. The opposite result holds – i.e., the propensity of getting vaccinated is higher among risk-neutral individuals than among risk-averse ones – when side effects are more severe but less likely to occur. Finally, we show that the combination of the severity and probability of side effects that reverses the relationship between risk aversion and vaccination depends on the individual’s degree of absolute prudence, suggesting that this attitude toward risk is another driver of the demand for vaccination.

Co-auteur: Sarat Chandra Akella (PSE)
Abstract: After a decision under ambiguity or compound risk, the probabilities associated with the resolution of the final outcome may remain unknown forever or be revealed either before (ex-ante) or after (ex-post) the resolution. Using an integrated discrete-choice experiment, this paper investigates preferences for ex-ante and ex-post information about probabilities under ambiguity and compound risk, in addition to attitudes toward uncertainty in both domains. Our results reveal model-free behavioral patterns and also support an econometric implementation of source theory, capturing preferences along two key dimensions: elevation and likelihood sensitivity. We find demand for both ex-ante and ex-post information that is likelihood-independent and highly correlated both within and across domains, suggesting the presence of a stable behavioral trait. Moreover, the information premium is positively correlated with ambiguity attitudes, but not with compound risk attitudes. These findings offer new insights into the relationship between ambiguity aversion, compound risk aversion, and the demand for information.

Co-author: Pauline Madies (Sciences Po)

Abstract: Gender homophily, the tendency to associate with people of the same gender, affects hiring, mentoring, and labor market outcomes. We propose a new experiment to study gender homophily with endogenous team formation and performance feedback. Each participant chooses a male or female partner before performing an individual real-effort task with a shared payoff. We vary performance feedback across treatments to test whether it affects the gender of the chosen partner. We find no gender differences in performance or beliefs, but clear differences in homophily. Men show no homophily, whereas women more often choose female partners. This pattern is entirely driven by top-performing women. A simple conceptual framework shows how partner-specific altruism lowers the effort threshold, making female teams more attractive to high-performing women.

Abstract :We conducted a contextualized laboratory experiment to determine whether competition between wood buyers affects pro-environmental behaviour, that is, the adoption of new sus-

tainable biomass harvesting practices. We also tested the effect of a non-monetary incentive,that is signing a declaration that commits wood buyers who voluntarily sign it to act in a sustainable manner, on pro-environmental behaviour. Our results provide evidence that competition between wood buyers has an adverse effect on pro-environmental behaviour. Nevertheless, presenting a declaration to sign is effective in inducing wood buyers to act in a sustainable manner as it tends to correct unsustainable behaviour that emerges from competition.

Keywords : Forest; Timber harvest; Laboratory experiment; Non-monetary incentives; Commitment; Competition

Abstract : Reducing greenhouse gas emissions and lowering the risk of non-communicable diseases requires large-scale lifestyle changes, particularly in transport and food consumption. Yet behaviours such as car use or meat consumption are not merely individual choices: they are shaped by daily routines, structural constraints, and social context. This talk examines how high-impact lifestyle behaviours can be effectively shifted through three complementary pillars.

Auteurs : Pavlo Blavatskyy (Montpellier Business School), Elias Bouacida (Universite Paris 8), Jianying Qiu (IMR, Department of Economics, Radboud University) et Liu Shi (IMR, Department of Economics, Radboud University)
Abstract : This paper studies individuals' perceived stochasticity in their own future choices. We elicit subjects' beliefs about how they will decide in 26 risky lottery choice problems and subsequently observe their realized choices. To further characterize individual-level choice stochasticity, we repeat 15 of these problems six times for each subject.
We find that 89% of subjects report non-degenerate beliefs about their future choices, which arise in 69% of all decision problems. These beliefs are predictive of realized behavior and match the stochastic choice distributions revealed through repeated decisions, suggesting that individuals have meaningful insight into the probabilistic nature of their own future choices. Beliefs elicited as intended choices display systematic behavioral biases: they exhibit a pronounced common ratio effect and, to a lesser extent, a reverse common consequence effect. We provide evidence that these patterns largely reflect underlying preferences for such effects, although stochasticity remains a contributing factor (Loomes, 2005; McGranaghan et al., 2024). Finally, we show that the prevalence of non-degenerate beliefs cannot be accounted for by choice noise, indifference, or random preferences. While quasi-concavity in probabilities explains behavior for a subset of subjects, it does not account for the majority, highlighting the role of other mechanisms - most notably preference uncertainty - in shaping stochastic choice and beliefs about one's own decisions.

Abstract : Nudges like Home Energy Reports have been shown to reduce energy use, but their impact is highly heterogeneous. We provide one of the first experimental explanation of this heterogeneity through a year-long field experiment with 150 students living in 82 apartments, combining detailed heat consumption data with survey and experimental measures of pro-environmental attitudes and economic preferences.

We find that HERs reduce average heat consumption by around 7%, consistent with the upper range of existing estimates. Yet, households with stronger pro-environmental attitudes—already consuming less than their peers—reduced usage by nearly 25% more, while the highest-consuming households showed no reduction or even an increase. These findings suggest that social-comparison nudges may act as a form of “moral tax,” affecting individuals unevenly across the consumption distribution and raising important questions about fairness in the design of energy efficiency policies.

Co-authors: Ilke Aydogan and Loïc Berger
Abstract: Measuring ambiguity attitudes with monetary incentives is often logistically complex, costly, and time-consuming. We propose and validate a simplified, introspection-based method that retains the core strengths of state-of-the-art approaches while being suitable for survey implementation. The method involves a hypothetical binary choice between a risky and an ambiguous option, followed by an introspective assessment of the strength of preference. We assess its validity by comparing it to incentivized matching probability measures in two experiments: a laboratory study with university students and an online study with a representative sample of the French population. Our findings show that the introspection-based method reliably captures ambiguity aversion but falls short in measuring ambiguity-generated likelihood insensitivity. These results offer new evidence on the strengths and limitations of non-incentivized approaches to eliciting ambiguity preferences and highlight their practical value in empirical research beyond the lab.

co-écrit avec Emmanuelle Lavaine et Marc Willinger
Abstract: Social interactions frequently involve situations in which rational, self-interested individualsare unwilling to sacrifice their private benefits for the sake of collective welfare. In the absence of adequate incentives, such behavior often leads to inefficient outcomes, where the pursuit of individual goals undermines the common good, a situation widely known as a social dilemma.
Two classic examples illustrate this problem: the public goods dilemma and the common-pool resources dilemma. The former captures the difficulty of financing goods or servicesthat benefit everyone, such as public safety, infrastructure, or healthcare. Withoutcompulsion or incentives to contribute, individuals are naturally tempted to free ride on thecontributions of others, thereby jeopardizing the quality and sustainability of these collectivegoods. The latter reflects the tension surrounding the exploitation of shared resources, suchas fisheries, forests, or water basins, where open access and rivalry in consumption often lead to overexploitation, the so-called “tragedy of the commons,” threatening long-termsustainability.
To address these imbalances, economists have proposed a range of institutional andbehavioral mechanisms. Some rely on top-down regulation, imposed by external authorities,including quotas, property rights, or corrective taxes. Others take a bottom-up approach, based on voluntary cooperation and community governance, where users monitor and enforce rules themselves through arrangements such as communication, collective voting, or binding agreements. While these approaches have sometimes succeeded in restoring cooperation, their effectiveness varies depending on the institutional context and the specific nature of the social dilemma under consideration. Our research explores new incentive-based frameworks designed to enhance coordination and align individual actions with socially desirable outcomes. These mechanisms typically operate through a two-stage process: in the first stage, individuals make their initial decisions or proposals; in the second, they are invited to evaluate or respond to the choices of others before implementation. This structure promotes transparency, mutual accountability, and convergence toward more efficient collective solutions.
The overarching goal of this research is to assess the ability of such mechanisms to mitigate social dilemmas, particularly in the contexts of public goods and common-pool resources, and to identify the institutional and behavioral conditions that underpin their success. The analysis pays particular attention to decision-making parameters, such as group size and collective approval rules, to better understand how different coordination structures influence cooperative behavior.

Co-auteurs : Julien Jacob, Eve-Angéline Lambert, Emmanuel Peterle.

Résumé : "Artificial intelligence (AI) technologies are increasingly being integrated into healthcare practice, particularly through decision support systems that aim to improve physicians' diagnostic and therapeutic judgments. While these tools have the potential to enhance clinical accuracy and efficiency, they also introduce risks of moral hazard, particularly when AI systems provide an initial medical diagnosis that may unduly influence the physician's independent assessment. This dynamic highlights the need to establish a consistent legal framework to ensure that healthcare professionals remain liable for verifying and interpreting AI-generated information. In the medical field, several liability regimes, such as strict liability and loss of chance, govern professional liability. Strict liability is a legal regime in which a person can be held liable for damage, regardless of any proven fault, as long as there is a causal link between the activity performed and the damage suffered. The doctrine of loss of chance, meanwhile, allows patients or their relatives to hold a physician liable when his or her negligent inaction deprives the patient of a significant opportunity to avoid harm. This article examines how different rules of legal liability influence physicians' behavior when an AI-generated preliminary diagnosis is presented, and how the existence, absence, or nature of these rules influences the degree to which physicians rely on AI recommendations. In addition, the study examines the potential substitutability between AI assistance and physician effort in formulating a diagnosis. Using an experimental methodology, theoretical and empirical analyses are conducted to assess the impact of different liability regimes on healthcare professionals' decision-making processes and their perception of AI-assisted diagnosis. The objective is to elucidate how different legal contexts (namely strict liability, loss of chance, and no liability) influence physicians' behavior in the presence or absence of AI-based diagnostic tools."

Abstract : The presentation combines two experimental studies on intergenerational cooperation in common-pool resources. The first examines how intragenerational conflict —when several individuals must coordinate within a generation— undermines sustainability, even when future generations are clearly identified. The second tests how framing the future —as near or distant generations, close kin, or through self-projection— shapes extraction decisions. Together, these experiments provide new evidence on how social conflict and psychological distance influence people’s willingness to preserve resources for future generations.

Avec Francis Bloch (PSE) et Sudipta Sarangi (Virginia Tech)

Abstract: We investigate rumors through a lab experiment where subjects who prefer sharing truthful information, are exposed to biased agents attempting to promote a specific opinion, regardless of its veracity. In our experiment, message content is minimal (Heads or Tails), network structure and agent types are known, but the source of the message is not known. Participants must assess the veracity of the message before deciding to share or block it. We find that network structure impacts the diffusion of rumors. While the majority of our subjects make few errors, they are much better at using the network as a filter than at computing the credibility of a message on their own. We also uncover two fundamental features of human behavior with regard to transmitting messages: subjects tend to overshare but they also care about the identity of the receiver. Thus, subjects want to be heard but care about who is listening to them.

Abstract:
Perceptions of inequality are shaped by how different dimensions of inequality are portrayed and communicated across traditional media, digital platforms, and online conversations. Leveraging large language models (LLMs), we study the global trends in the salience and pupillarity of inequality and its dimensions as well as the narratives driving its portrayal, and the conversation from YouTube videos and its discussions across English-speaking countries. This approach allows us to trace how public discourse evolves over time, identify the key drivers of change, and examine how these dynamics respond to turning points triggered by political and business cycles. We examine the main drivers of such trends and study how such trends are affected by turning points resulting from political and business cycles. Finally, we show that when political and business recessions coincide, these conversations tend to amplify polarization, accelerating the adoption of more extreme preferences and underscoring the powerful role of discourse and dialogue in shaping public attitudes toward inequality.

Co-écrit avec François Cochard, Xavier Hollandts, Eli Spiegelman
Abstract: Despite the explicit integration of social goals into their governance, members’ adherence to the cooperative is not guaranteed. Some of them are reluctant: they participate, but lack intrinsic commitment; opportunistic behaviors then can trouble the collective project. External observers may not trust that cooperative principles are really endorsed by members. This paper studies these issues with laboratory and lab-in-the-field experiments. Based on interviews and pilots with cooperative members, we adapt a standard linear public goods game to isolate the basic principles of cooperatives in a menu of institutions. To see whether the effects are specific to cooperatives, we implement choice frames of a cooperative, a general business enterprise, and an unframed “group”. Because cooperatives are fundamentally social structures, and therefore likely rely on norms for their effectiveness, we also apply a Keynesian “beauty contest” procedure to test the extent to which expectations of others’ behavior influences cooperation. Our main results show that, when compared to other groups, individuals in a cooperative frame contribute more. Nevertheless, in the lab, cooperative members have no strict preferences for institutions meant to induce more cooperation. In the field, wine producers engage in effective redistribution public goods, while their business partners fail to anticipate it.

Abstract: "The experimental literature on bargaining has largely focused on identifying bargaining power and the intriguing role of equal-split solutions as reference points in diverse bargaining settings. In contrast, the theoretical literature has devoted comparatively less attention to reference points and the related concept of loss aversion. Typically, most theoretical papers concentrate on solutions that Pareto-dominate the disagreement point and are Pareto efficient; hence, the reference point naturally inherits those properties. In this paper, we seek to bridge the gap between the theoretical and empirical literatures by examining whether bargaining agreements are influenced by an experimentally induced reference point. We conducted a laboratory experiment with 166 participants involved in bilateral bargaining, where participants were first endowed with points earned through a real-effort task. The results show that the reference point is not always chosen, even when it is Pareto-efficient. Notably, in scenarios with asymmetric fallback positions, some degree of disagreement remains, and a minority of pairs continues to favor egalitarian outcomes. Our results also show the emergence of an Equal-change solution as an alternative to the standard Egalitarian and Nash solutions."

Co-auteurs: David Craininch, Wanda Mimra

Abstract: Industry gifts to experts tasked with making decisions on behalf of their clients are a common phenomenon. A notable example is the pharmaceutical industry's provision of gifts to physicians, such as conference invitations and complimentary meals. In this paper, we analyze the impact of such gifts on experts' diagnostic effort and product recommendation behavior. Using a simple model, we demonstrate that a sufficient condition for these gifts to reduce an expert’s propensity to seek diagnostic information is that the expert's valuation of their client’s welfare remains constant or decreases with reciprocity for gifts. Additionally, we propose an experimental framework to empirically test these theoretical predictions.

Arash Talebi (EDHEC), Sonja Prokopec (ESSEC), Ayse Onculer (ESSEC)

Abstract: This research explores the paradoxical effects of uncertain price promotions, focusing on how low-probability gains can influence evaluations and future choices. Our findings reveal that receiving a low-value reward in an uncertain promotion is more disappointing than receiving no promotion at all—a result that contradicts conventional utility-based predictions. This effect arises from the interplay of upward and downward counterfactual comparisons: individuals compare their realized outcome both to the unattained high-value prize and the baseline of no promotion. This dual reference-point mechanism challenge the assumption that any positive gain enhances consumer satisfaction and offer new insights into the emotional and cognitive biases that shape decision-making under uncertainty. Implications for designing more effective and psychologically attuned promotional strategies are discussed.

Co-auteurs : Noémi Berlin, Tarek Jaber-Lopez et Anne-Laure Levet

Abstract :

In a context of underconsumption of fruit and vegetables, particularly among disadvantaged populations, as well as rising poverty, food insecurity, and inflation, we are conducting an experimental study in France on the impact of financial incentives on the consumption of fruit and vegetables among low-income households. The aim is to guarantee universal access to healthy and sustainable food for all and thereby mitigate long-term health issues associated with poor diets.

This longitudinal study analyzes the effects of two distinct incentives (immediate or deferred) over a four-month period, divided into three phases: pre-intervention, intervention, and post-intervention. In addition to weekly purchase records, we conducted a qualitative phase designed to identify the drivers and barriers associated with each type of intervention.

This research enhances the understanding of financial incentive mechanisms regarding fruit and vegetable consumption and helps identify the optimal incentive measure for low-income households in France, considering individual preferences, socio-economic barriers, and perceptions related to autonomy and dignity.

Abstract: Tuition fees of business schools typically represent an important financial burden for students and their families. Could this financial strain impair the cognitive functions of students from more disadvantaged backgrounds, and in turn their academic performance? We address this question by analysing the impact of the introduction of means-tested tuition fees for first-year students at a French business school. Using cognitive measures, we find that the difference in the performance at a Raven’s matrices test between economically disadvantaged first-year students, who obtained a fees reduction, and their counterpart in later-years, who paid the full fees, is significantly improved (more positive) in favour of the former, compared to the difference between first and later-year students overall. We find no such effect on the other cognitive measures (i.e. Stroop task and Cognitive Reflection Test) nor on a synthetic measure based on the three cognitive tasks. At the intensive margin, the increase with poverty levels of the fees’ spread between beneficiaries and non-beneficiaries does not accentuate the positive effect on the performance to the Raven’s matrices test, but it does so on the synthetic measure. This suggests a more broad-based positive cognitive effect of the program for the most economically disadvantaged. At the academic level, using administrative data, we found no total effect of the reduced tuition fees on the average grade of students, but mediation analyses demonstrate a positive indirect effect through improved cognitive abilities, at both the extensive and the intensive margins.

Abstract : A persuader influences a decision-maker by providing a model for interpreting some upcoming news. The decision-maker adopts the model if it does not distort the marginal
distribution of news. Both parties can benefit if the persuader can provide news contingent, overall incoherent, models, privately learn the truth, or design the process of news arrival.

Coécrit avec Vassili Vergopoulos (Paris 2, Lemma).

Abstract: In this paper, we propose an axiomatic characterization of new allocation rules that take as input the marginal value of each agent in various possible worlds and output a potential division of the value produced in each world. We axiomatize a specific family of rules that integrates both marginalist and egalitarian principles. Finally, we show that this framework extends the cooperative game theory and we establish a connection with the Shapley value.

coécrit avec Yannick Gabuthy, Eve-Angéline Lambert, et Sébastien Massoni

Résumé : This paper explores the possibility that a taxation mechanism always implements a Pareto-optimal allocation in bilateral exchange when the market participants behave strategically and non cooperatively. To this end, we reconsider the taxation mechanism, namely the endowment taxation with transfers, implemented in the strategic bilateral exchange models by Gabszewicz and Grazzini (JPET, 1999). In this framework of strategic bilateral exchange, we consider a general class of smooth utility functions, and we determine the conditions under which the taxation mechanism is Pareto-optimal, i.e., whether there exists an equilibrium tax such that endowment taxation with transfers always implements a Pareto-optimal allocation. Furthermore, we explain why this taxation mechanism could implement a Pareto-optimal allocation.

Co auteur : Anthony Chung (ESCE)

Abstract : L’industrie textile est l’une des industries les plus polluantes au monde, et est responsable de 20 % de la pollution d’eau potable, 10 % des émissions de gaz à effet de serre et à l’origine d’une quantité importante de déchets. Cependant, le rapport de Forbes de 2019 révèle que, même si 52 % des consommateurs souhaitent que l'industrie de la mode adopte des pratiques plus durables, seuls 29 % seraient prêts à payer plus cher (un surprix responsable) pour des versions des mêmes articles fabriquées de manière plus durable. Bien que des recherches aient étudié les facteurs influençant l’intention de payer un surprix pour des produits alimentaires (Anselmsson, Johansson et Persson, 2007 ; Loureiro, McCluskey et Mittelhammer, 2002 ; Steenkamp, Van Heerde et Geyskens, 2010) ou dans le secteur des services hôteliers (González-Rodríguez, Díaz-Fernández et Font, 2020), aucun article ne traite de l’intention de payer un surprix dans le secteur du textile. A l’ère où les grandes enseignes de fast fashion explosent encore telles que Shein (croissance de 100 % entre 2021 et 2022) de par leurs prix très faibles, il s’avère crucial d’étudier les facteurs qui encouragent les consommateurs à payer un surprix pour un produit textile plus écologique. Nous proposons dans ce papier d’étudier plus particulièrement (1) dans quelle mesure un affichage environnemental, traduit par un Eco-score, influence l’intention de payer un surprix ; et (2) quel(s) niveau(x) de score d’affichage (éco-score A à E) entraîne(nt) une plus grande intention de payer un surprix comparativement à l’absence d’affichage. L’objectif de cet article est de prouver empiriquement que la généralisation d’un affichage environnemental pour les vêtements favorise l’intention de payer un surprix. Pour répondre à cette question, nous mobilisons la littérature sur la théorie du signal (e.g. Boulding et Kirmani, 1993 ; Nabec et al., 2022) et la Value Belief Norm (VBN) (e.g. Bertrandias, Cazes-Valette et Gurviez, 2021). Une collecte de données quantitatives sous la forme d’une expérimentation met au jour les rôles médiateurs de la culpabilité, la perception de l’image verte et les pratiques environnementales de l’entreprise sur la relation entre l’affichage environnemental et l’intention de payer un surprix.

Co-écrit avec Brian Rogers.
Abstract: The assumption of rationality and higher-order reasoning about rationality underpins many models of strategic behavior. We investigate the degree to which this assumption holds in a simple incomplete information game and how that depends on the particular informational environment of the game. The project aims to provide a simple framework for identifying higher-order rationality in incomplete information games and test the implications of different types of information structures on the players’ displayed orders of rationality. We have run a lab experiment and collected data from 115 participants across three treatments, holding the basic game fixed and varying the information structure, where information structures across treatments are ranked in terms of contingent thinking difficulty. We are able to obtain within-subject comparisons of the degree to which more difficult information structures impact the levels of rationality of players.

Co-auteurs: Greg Kubitz et Alice Soldà.

Résumé : This paper investigates whether individuals use information complexity as an excuse to remain ignorant so as to behave more selfishly. We study this question in a context where individuals face a trade-off between their monetary payoff and their pro-environmental preferences. We propose that individuals use information complexity as an excuse to make self-serving mistakes, which allow them to behave more selfishly without compromising their pro-environmental image. To test this idea, we conducted an online experiment in which we varied (i) the complexity of the information regarding the environmental impact of a donation and (ii) whether there is a trade-off between participants' selfish motives and pro-environmental preferences. In line with our hypothesis, we found that participants make more mistakes when information is complex, but even more so when there is a trade-off between their monetary payoff and their pro-environmental preferences. Our findings suggest that pro-environmental individuals do 'play dumb' when doing so gives them an excuse to behave more selfishly without compromising their image

Co-auteures : Magali Dumontet, Johanna Etner, Meglena Jeleva

Abstract : In the term life insurance market, individuals pay a premium covering their death. Insurers secure a certain amount of money that will be paid to beneficiary(ies) in case of death of the policyholder. One contract can differ from another in many ways: the level of private information asked to applicants, the presence of riders in the contract or how the claim is paid. Understanding how individuals' demand is influenced by those possibilities is not straightforward. This research question is approached through a Discrete Choice Experiment on a sample representative of the French population. This method permits to estimate individuals’ behavioral characteristics that influence (1) the term life insurance purchasing decision and (2) Willingness to Pay for each feature of the term life insurance contract. The study is valuable for insurers who want to gain insights into consumers' life insurance purchase behavior, especially for professionals who are involved in product development and marketing.

Co-auteurs: Pietro Biroli, Marina Della Giusta

Abstract: Bias, both conscious and unconscious, perpetuates inequalities within educational settings, impacting teachers and students alike and it is important therefore to establish the extent to which teachers can recognise it so they can activate mitigation. We develop an image-based bias recognition test (IBRT) in which we ask teachers to rate the presence of stereotypes in 20 randomly selected images from a pool of 100 drawn from educational catalogues used in textbooks and systematically relate their ratings and comments to established measures of both implicit bias, the Implicit Association Test (IAT) and explicit bias as declared in and self-reported social values from the European Social Survey (ESS).

Co écrit avec Noémi Berlin et Tarek Jaber Lopez
Abstract: In a lab-in-the-field experiment, we investigate the influence of social norms on parents’ beliefs regarding the nutritional quality of food items and their subsequent food choices. We use a 3x2 between-subject experimental design, where we vary two factors: 1-the information provided (control vs. descriptive norm vs. an opinion) and 2-the recipient of the food decisions made by parents (for their own child vs. for another random child). A total of 300 parents report their beliefs about the nutritional score of food items twice and create two sets of food baskets: in a first stage, they respond without any specific information, whereas in a second stage they receive specific information depending on the treatment to which they are assigned. Using difference-in-difference estimation, we find that only the descriptive norm significantly reduces parents' overestimation rate of items' nutritional quality. "Opinion" significantly improves the nutritional quality of both, the parent's and child’s baskets. In contrast, the descriptive social norm only significantly improves the nutritional quality of parent’s food baskets.

Co écrit avec Fabrice Le Lec et Rémi Suchon

Abstract: We explore how individuals apply self-protection strategies to both themselves and charitable organizations, focusing on their willingness to pay to reduce the probability of the worst outcome by 10 percentage points across five different probability levels: 0.1, 0.2, 0.5, 0.8, and 1.0. This research, building on Le Lec et al.'s working paper and utilizing Exley's 2016 method, involves four experimental scenarios. Two of these scenarios measure the personal cost individuals are willing to incur to decrease these probabilities by 10 points, either for themselves or for a charity. The other two scenarios investigate the costs individuals are willing to impose on a charity to reduce these probabilities by 10 points, affecting either the charity itself or the individuals. Our very preliminary findings reveal a tendency for individuals to assign higher costs to charities, regardless of whether the risk reduction benefits themselves or the charity. Additionally, we observe a significant impact of the initial probability of experiencing the worst outcome on the willingness to pay, suggesting that the probability weighting function plays a crucial role. However, this propensity to pay or to impose costs appears to be only marginally influenced by the experimental conditions.

Authors : Gashaw T. Abate(IFPRI) , Tanguy Bernard (BSE , Université de Bordeaux) , Joshua Deutschmann (Development Innovation Lab, University of Chicago) , Fatou Fall (LEDa-DIAL, Université Paris-Dauphine-PSL)
Abstract : Why would farmers invest in technologies that protect the health of their consumers if there are no market rewards associated with food safety? We work with a sample of small-scale groundnut farmers in Senegal, where aflatoxin contamination is a major health concern. We rely on a lab-in-the-field experiment where we elicit their willingness to pay (WTP) for aflatoxins detection in groundnut powder dedicated to their own consumption, donation to local children, or sales at a premium. We find lower WTP for donation, albeit limited to farmers with less than medial reported level of altruism. In turn, a randomly allocated information treatment on the health consequences of aflatoxins increases overall WTP for donated groundnuts and eliminates the effect of altruism.

co-écrit avec Brice Corgnet and Camille Cornand

Résumé: 

Since Barro (2006), the macro-finance literature has shown that accounting for rare macroeconomic disasters helps explain various long-lasting empirical puzzles in financial asset markets through the critical role of disaster risk perceptions. However, individual macroeconomic disaster risk perceptions and their consequences for financial investment have never been directly measured at the microeconomic level.

To fill this gap and investigate whether communication on macroeconomic disaster risk can affect individual perceptions and financial investment decisions, we ran an online experiment on 345 French finance and macroeconomics professionals. We randomly assigned participants to three distinct informational treatments about the past frequency of macroeconomic disasters in a given historical sample (low-precision treatment, high-precision treatment, and salient treatment). We asked participants to estimate this frequency prior and posterior to the treatment and to allocate a sum of money between a risk-free asset and a risky asset whose returns depend on the possibility of a macroeconomic disaster.

We find that, on average, participants significantly overestimate the past frequency of macroeconomic disasters before information provision. At the intensive margin, participants decrease their frequency estimate and uncertainty and increase investment in the risky asset following the treatments. At the extensive margin, the high-precision treatment increases the probability of updating the prior relative to the two other treatments. We also investigate the role of individual variables such as gender, financial literacy score, confidence in prior estimate, and sector of activity.

Abstract: We investigate individuals’ food choices at the restaurant with information about the environmental impact of the meals. We ask whether information about CO2 emissions of the main meal on a restaurant menu alters the choice of guests between beef and sea trout under high or low social influence of other guests around the table. We followed a 2 x 2 design differentiated by the information given or not and the high or low social influence. For guests with the information, they could read on the menu that consuming beef participates more to climate change than consuming sea trout; guests without information had only the meals presented on the menu. For guests with the high social influence, they were allowed to discuss before making their choice of the main meal whereas for guests with the low social influence, they had to choose their main meal without communication with other people around the table. We also asked guests to reply to a short questionnaire about their meal preferences and their expectations regarding other guests’ food choice of the main meal, i.e. the social norm. Experiments were run at the Living lab of the Institut Paul Bocuse in Lyon, France, between April and June 2022. In total, 486 guests participated. The results show that the guests’ normative beliefs about the choice of fish as being socially acceptable increase when they receive the information about CO2 emissions which in turn significantly affects the choice of fish. The fish is slightly more chosen when the guests receive the environmental information and are allowed to discuss before ordering, but this effect is not significant. 

Abstract: I analyze Dutch panel data that contains rich information on voting, political opinions, and personality traits. I show that “adversarial” economic preferences – competitiveness and negative reciprocity – but also “prosocial” preferences including trust and altruism are strong predictors of political preferences, with predictive power similar to household income. Past studies have shown that standard personality traits are reliably linked to political preferences. I replicate these associations and show that competitiveness and social preferences predict voting independently from – and often with larger effect sizes than – these other traits. The complex Dutch party landscape allows me to go further than a simple left-right comparison to show that associations between individual traits and political preferences are non-linear along the left-right spectrum. Competitiveness predicts voting for center-right, economically liberal parties whereas social preferences are stronger predictors for voting for the populist far right. Put differently, competitiveness predicts voting for parties that are economically conservative whereas negative reciprocity and low pro-sociality predict voting for parties that are socially conservative.

Co-écrit avec Laurent Denant-Boèmont

Abstract:
We investigate how ego depletion might impact cooperation levels for individuals. To this end, we propose a theoretical model in which an individual contributes to a public good in a VCM (Voluntary Contribution Mechanism) game after having been exposed to ego depletion. This model first aims at specifying the main parameters of the depletion function at the individual level and, second, to provide a theoretical relationship between individual characteristics of the depletion function and the contribution level. We use this model to build an economic experiment where participants enter a VCM game after having been exposed to ego depletion. Our experimental treatments vary in the degree of ego depletion to isolate the effect of this latter on contribution. First experimental results highlights the impact of self control in the level of contribution in a one-shot public good game. In particular, we observe a strong and negative relationship between ego-depletion and the level of cooperation while the initial level of willpower fails to explain the level of contribution.

Abstract:
The study of gender differences in competitiveness has been a widely explored topic in experimental economics, with a focus on its contribution to the gender wage gap. Recent research in psychology has employed virtual reality (VR) to manipulate individuals' embodiment in bodies with different characteristics, including gender. This has been shown to alter the perception of the self, with participants who underwent a 'gender swap' via VR identifying more with the opposite gender and exhibiting self-attribution of traits stereotypically associated with that gender, such as competitiveness. To test whether these self-reported results on attitudes extend to behavior, I examine the impact of such a virtual “gender swap” on selection into competitive environments in the lab. Although the VR intervention impacted several secondary outcomes, including overconfidence, it did not have a significant effect on the gender gap in tournament selection. The results have implications for the study of embodiment interventions and gender differences in competition.

Coécrit avec Mathieu Lambotte, Anna Risch et Sandrine Mathy (GAEL)

Résumé : We investigate the role of peer effects in the workplace on individual choices of active transportation mode. We collect original data through an online survey on networks and sustainable behaviors among 334 individuals working in ten laboratories of the University of Grenoble Alps in February 2020. We apply linear and non-linear models of peer effects on active modal choice, untangling the role of conformism and strategic complementarity in social influence. We show that given our data, a linear local-average specification is the preferred empirical model of peer effects and we estimate strong and significant endogenous peer effects.

Résumé : We experimentally study how individuals read strategically-transmitted information when they have preferences over what they will learn. Subjects play disclosure games in which Receivers should interpret messages skeptically. We vary whether the state that Senders communicate about is ego-relevant or neutral for Receivers, and whether skeptical beliefs are aligned or not with what Receivers prefer believing. Compared to neutral settings, skepticism is significantly lower when it is self-threatening, and not enhanced when it is self-serving. These results shed light on a new channel that individuals can use to protect their beliefs in communication situation: they exercise skepticism in a motivated way, that is, in a way that depends on the desirability of the conclusions that skeptical inferences lead to.

Co-auteurs : Vincent Lenglin (Anthropo-Lab, Université Catholique de Lille), Joel Santos (IESEG, EDHEC)

Co auteurs : Loukas Balafoutas et Brit Grosskopf (University of Exeter, United Kingdom)

en collaboration avec Sofiia Mun (Paris School of Economics)

en collaboration avec Vincent Teixeira

co-écrit avec Pierre Fleckinger et Christian Waibel.

écrit en collaboration avec Arthur Attema, Jocelyn Raude, Valérie Seror, The COCONEL Group

co-écrit avec Loukas Balafoutas, Mehdi Feizi, et Björn Vollan.

co-écrit avec Noémi Berlin

co-écrit avec Johanna Etner et Meglena Jeleva

co-écrit avec Patrick Roger et Marc Willinger

co-écrit avec B. Ouvrard, A. Reynaud et L.Tuffery

co-écrit avec Raphael Soubeyran et Nicolas Querou

Co-écrit avec Fabienne Llense et Jekaterina Dmitrijeva

Price discrimination based on consumers' personal data has become common practice in many markets. We analyze the willingness to share personal data when this data is used for pricing in subsequent markets. In a laboratory experiment, participants can sell a bundle of personal data. Participants are categorized based on the content of their personal data and receive category-dependent payoffs in a subsequent stage. The experimental variations change category-dependent the payoff structure. We find no effect of subsequent price discrimination on the general willingness to sell personal data. A significant change in the price of personal data is only observed under strong negative price discrimination. Furthermore, we find important gender differences in data selling price adjustments and the role of underlying privacy concerns.

co-écrit avec Lydia Ashton (University of Wisconsin-Madison. Wisconsin Institute for Discovery) et Emmanuel Kemel (HEC Business School Paris & GREGHEC, CNRS)

Classic economic theory focuses on static and stable preferences. However, there is growing evidence that cognitive, emotional and visceral states (e.g. stress, hunger) can mediate behavioral biases and shape preferences (DellaVigna, 2009). In particular, Symmonds & al. (2010) and Levy & al. (2013) provide evidence that risk attitudes fluctuate with metabolic states. In this paper, we follow this stream of research and propose an experimental design with a specific hunger manipulation mechanism and an original risk attitude elicitation tool that allows parametric estimation of the components of Prospect Theory (PT) by using a convex budget line (CBL) allocation methodology (Choi & al., 2007).

Participants (N=107, Xlab Berkeley) were required to fast for at least three hours before the experiment and completed a high-protein shake tasting activity before/after (randomly assigned) the risk attitude elicitation questionnaire. Our results suggest a limited impact of hunger on the utility function and loss aversion parameters. However, we find that hungry (fasting) participants display significantly more risk aversion (curvature of the utility function) and probability distortion (inverse S shape of the probability weighting function) than the satiated participants. These results are consistent with and extend the existing empirical evidence on satiation and risk attitudes and feed the debate on the impact of hunger on economic decision

co-écrit avec Pierpaolo Battigalli (Bocconi University and IGIER, Milan) & Rosemarie Nagel (ICREA, Universitat Pompeu Fabra, Barcelona GSE)

- de 10h00 à 11h00

Marie Pierre Dargnies (Université Paris Dauphine) présentera un protocole expérimental sur le thème :

"Speed and information in financial trading: Experimental design"

- de 11h00 à 12h15

Léontine Goldzahl (Edhec Business School) présentera un article intitule:

"Health Insurance decision: a theoretical and experimental investigation"

avec David Crainich (CNRS, IESEF School of Management), , Florence Jusot (Université Paris Dauphine, PSL), Doriane Mignon (Université Paris Dauphine, PSL)

Béatrice Boulu-Reshef, Graciela Kuechle, Luise Rohland

Entrepreneurs may differentiate their ventures and attract investments by advertising that their firm produces positive externalities for society. Such signaling of entrepreneurs’ trustworthiness may be a prevalent practice in these investment opportunities which are casually referred to as “impact investment’’ by practitioners. This paper investigates this possible signaling by studying the interplay of altruistic, fiscal, and reputational motives that characterizes these investments in a laboratory experiment. In the experiment, the investor may transfer money to the entrepreneur, who may then invest some, all or none of this money onto a conventional investment opportunity or an impact investment opportunity involving a spillover, and then decide whether or not to transfer some of the funds back. Entrepreneurs choose a type of investment and their choice is visible to the investors. The results are that the choice alone of an impact project does not increase investors’ transfers to impact investments but a higher spillover does as long as the tax from possible gains is not too high. Pro-social entrepreneurs do not announce higher rates of spillovers. In the presence of tax, entrepreneurs internalize that a too high spillover could scare away investors. The experiment shows that the presence of impact investments helps investors coordinate onto different investment types. It identifies the mechanisms behind investors believing that socially-oriented entrepreneurs will be more trustworthy. Specifically, as investors’ transfers react to the effective societal impact and not to the mere project type, making that quantitative information visible allows investors to differentiate between investment opportunities.

We investigate the role of preferences for risk on health and sexual behaviours of 805 female sex workers in Senegal, of whom 441 were surveyed twice at a two-year interval. Risk preferences were measured using simple incentivised risk elicitation tasks as well as domain specific risk-taking scales. We find that the experimental measure was poorly correlated with self-reported measures. We further find that risk preferences were highly stable across domains and fairly stable over time. Our main result indicates that risk preferences measured in the lab are a main predictor of sex workers' health and behaviours. We find that risk averse sex workers demand more preventive services and are less likely to engage in risky sex and, as a result, are less likely to be infected with sexually transmitted infections, including HIV/AIDS. Hence, our results conrm the role of risk preferences in the spread of HIV/AIDS epidemic.

En collaboration avec D.A. Regier et V. Watson

Co-écrit avec MA Diaye et S. Pekovic