Publications

29. Improving compliance with COVID-19 guidance: a workplace field experiment (with Danae Arroyos-Calvera, Johannes Lohse and Rebecca McDonald). Behavioural Public Policy (2023), 1-23 [Link].

Abstract: Compliance with hygiene and other safety measures in the workplace continues to be a vital component of society's strategy for reducing infections in the long-term management of COVID-19. We report the results of a field trial of well-established behavioural interventions (social norms, pledging, messenger effects) we implemented to improve compliance with such measures in an occupational setting. We use daily reports of own and other's behaviour to assess the effects of these interventions, and supplement these subjective measures with objective data on hand sanitiser usage. The behavioural interventions tested have signicant but quantitatively moderate effects on subjective compliance measures and minimal effects on sanitiser usage. All effects of our interventions are short-term in nature and dissipate shortly after implementation. Our findings thus provide weak support for the hypothesis that interventions supported by a large body of behavioural work can help support compliance with infection prevention measures in the workplace.

28. The impact of group identity on experimental markets with externalities (with Francisco Gómez-Martínez), European Economic Review (2023), vol. 158, 104544  [Link] Open Access

Abstract: Existing evidence demonstrates that the degree of social homogeneity in a society correlates with various economic indicators. Using experimental techniques, we establish the causal impact of social proximity on socially responsible behavior, market prices and income inequality. We develop an experimental market where low-cost production generates a negative externality to a third party, while high-cost production eliminates the externality. We compare behavior in groups varying whether the third party shares a common identity with buyers and sellers (in-group condition) or not (outgroup condition). Our findings indicate that socially responsible behavior is generally robust across our treatments. However, reducing social heterogeneities improves economic welfare indicators as it leads to a striking reduction of economic inequality through changes in market price levels and improves market efficiency. Overall, our experiment shows that the social structure of market environments matters a great deal and has significant implications for the design of institutions.

27. Dictator giving and taking: Evidence from Africa, Journal of Economic Behavior  & Organization (2023), vol. 209, pp. 631-649  [Link] Open Access

Abstract: Replication lies at the heart of economic analysis and is of crucial importance for science progression. Previous studies find evidence that framing significantly matters in dictator games. These findings mostly rely on societies considered as being WEIRD. We explore the generalizability of these results by collecting data from 165 dictators in Botswana. Our findings show that average giving is significantly reduced when the action set includes taking, but by substantially less than what has been found previously in a WEIRD society. We calculate the post-study probability estimates showing how our priors change with the results reported here. Our study further highlights the importance of institutions and has significant implications for future research.

25. Leadership under the shadow of the future: intelligence and strategy choice in infinitely repeated games (with Graeme Pearce), European Economic Review (2023), vol. 152, 104372 [Link] Open Access

Abstract: We examine the impact of intelligence on decision making in an infinitely repeated sequential public goods game. Using a two-part experiment, we collect data on subjects’ intelligence and a wide range of preference characteristics, and match these to their full contingent strategy profiles. We find that leaders are less likely to play a free–riding strategy as their intelligence increases. Followers are less likely to play a grim–trigger strategy as intelligence increases. Performing simulations using players’ strategies, we find that groups contribute more and are more profitable as intelligence increases. Our results have implications for the design of policies promoting group success.

24. Is there a link between intelligence and lying? (with Graeme Pearce),  Journal of Economic Behavior  & Organization (2023), vol. 206, pp. 182-203 [Link] Open Access

Abstract: In this paper we study the link between intelligence and lying. This is done under two distinct experimental paradigms: the die rolling paradigm, and the mind game paradigm. We compare the behaviour of subjects conditional on their intelligence in each of these paradigms when lying benefits the subject who lies (Selfish treatment) or a charitable cause (Charity treatment). We report some evidence that lying increases when it benefits a charitable cause, and limited evidence that more intelligent individuals increase lying when doing so benefits a charity. Our results are consistent with models of self–image concerns, and could have important implications for the existing lying literature.

23. Feedback quality and performance in organisations (with Paola Paiardini), The Leadership Quarterly (2022), vol. 33, 101534 [Link]

Abstract: The provision of feedback is fundamental for promoting employee performance in modern organisations; however, little is known about how the quality of feedback affects performance. We report an experiment where subjects perform a real-effort task repeatedly in a flat-wage environment which varies feedback quality across treatments. In the baseline treatment, subjects receive no feedback about their rank in their group. In the two main treatments, feedback quality varies in that subjects know (“High-Quality Feedback”) or do not know (“Low-Quality Feedback”) their exact rank in their group. We show that the quality of feedback is an important driver of productivity. Average performance is significantly higher for high-quality feedback than for low-quality or no feedback, where no significant overall performance differences are observed. Our results have significant implications for designing and implementing cost-effective policies within organisations.

22. Can Charitable Appeals Identify and Exploit Belief Heterogeneity? (with Benjamin M. Marx),  Journal of Economic Behavior  & Organization (2022), vol. 198, pp. 631-649 [Link]

Abstract: Charitable fundraisers frequently announce giving by others, and research shows that this can increase donations. However, this mechanism may not put information about peers to the most efficient use if it is costly to inform individuals who are indifferent to peer actions or causes some individuals to give less. We investigate whether a simple mechanism without incentives can predict heterogeneity in charitable responses to peer decisions. We elicit beliefs about donations in a baseline solicitation, and in subsequent solicitations we randomly assign information about others’ donations. We find that elicited beliefs are often logically inconsistent and that many subjects fail to update beliefs when treated. Elicited beliefs did not predict heterogeneous treatment effects on beliefs or donations, making the strategy unlikely to succeed unless individuals are engaged and the information is salient.

21. Cooperation in a Fragmented Society: Experimental Evidence on Syrian Refugees and Natives in Lebanon (with Bilal Malaeb, Michael Vlassopoulos and Jackline Wahba), Journal of Economic Behavior  & Organization (2021), vol. 187, pp. 176-191 [Link]

Abstract: Lebanon is the country with the highest density of refugees in the world, raising the question of whether the host and refugee populations can cooperate harmoniously. We conduct a lab-in-the-field experiment in Lebanon studying intra- and inter-group behavior of Syrian refugees and Lebanese nationals in a repeated public goods game without and with punishment. We randomly assign participants to Lebanese-only, Syrian-only, or mixed sessions. We find that randomly formed pairs in homogeneous sessions, on average, contribute and punish significantly more than those in mixed sessions, suggesting in-group cooperation is stronger. These patterns are driven by Lebanese participants. Further analysis indicates that behavior in mixed groups is more strongly conditioned on expectations about the partner’s cooperation than in homogeneous groups.

20. The impact of smiling cues on social cooperation (with Brit Grosskopf), Southern Economic Journal (2021), vol. 87, pp. 1390-1404. [Link] Open Access

Abstract: While there is a plethora of experimental studies on the effects of pre-play communication on economic behaviour, little is known about the impact of simple cues, such as smiling, on pro-sociality. This paper presents a comprehensive analysis exploring how the presence of a smiling opportunity affects pro-social behaviour as measured by a one-shot linear public goods game. Our design varies i) whether smiling is costly or costless, and ii) whether one or both members in a group are given the opportunity to smile. To test for the robustness of our results, we consider two versions of smiling cues: i) a smiling label and ii) a smiling face (emoji). Our findings indicate that introducing a cost for smiling has detrimental behavioural consequences regardless of the cue. Specifically, when smiling is costly, only a small minority of subjects are willing to smile as opposed to when smiling is costless. As a result, subjects contribute significantly less. These results remain the same regardless of the type of smiling cue that subjects can send. Overall, our findings provide new evidence that simple cues such as smiles embody information that influences pro-social behaviour in social interactions.

19. Dimensions of Donation Preferences: the Structure of Peer and Income Effects (with Benjamin M. Marx), Experimental Economics (2021), vol. 24, pp. 274–302 [Link]

Abstract: Charitable donations provide positive externalities and can potentially be increased with an understanding of donor preferences. We obtain a uniquely comprehensive characterization of donation motives using an experiment that varies treatments between and within subject. Donations are increasing in peers’ donations, past subjects’ donations, and bonus income. These findings of peer and income effects do not extend to earned income, anonymous donations, or peers’ donations of bonus income. A model of an uncertain social norm for giving can explain the patterns here and in several strands of past research. Estimation of the model reveals substantial heterogeneity in subjects’ adherence to the norm and perceptions of its form. Correlations between these dimensions of preferences are such that charities with perfect information could increase net revenue using targeted give-aways to certain donors. A simpler fundraising strategy using only the social dimension of donor preferences increases donations by 30 percent.

18. Competition and the role of group identity (with Francesca Cornaglia and Paolo Masella), Journal of Economic Behavior  & Organization (2019), vol. 162, pp. 136-145 [Link]

Abstract: The emergence of competition is a defining aspect of human nature and characterizes many important social environments. However, its relationship with how social groups are formed has received little attention. We design an experiment to analyze how individuals’ willingness to compete is affected by group identity. We find that individuals display substantially stronger competitiveness in within group (ingroup) matchings than in between group (outgroup) matchings or in a control setting where no group identity is induced. We also find that the effect of group identity is stronger for subjects who participated more actively in the team-building task.

17. Does revealing personality data affect prosocial behaviour? (with Nikolaos Georgantzis), Journal of Economic Behavior  & Organization (2019), vol. 159, pp. 409-420 [Link]

Abstract: Many modern organisations collect data on individuals’ personality traits as part of their human resource selection processes. We test experimentally whether revealing information on personality data impacts on pro-social behaviour as measured in a one-shot modified dictator game and a public goods game. Our focus is on the personality trait of agreeableness which has been shown to be a significant determinant of pro-sociality. We provide new evidence that revealing personality information for disagreeable individuals has detrimental effects on their pro-social behaviour as compared to the baseline no-information benchmark. This is not the case, however, for agreeable individuals when they are matched with agreeable individuals. Agreeable individuals become less pro-social when matched with disagreeable individuals and are aware of this. Our results suggest that information cues about personality significantly affect economic behaviour and have implications for employees’ personality assessments as part of standard hiring processes.

16. Prosociality Spillovers of Working with Others (with Benjamin M. Marx), Journal of Economic Behavior  & Organization (2018), vol. 155, pp. 2015–216 [Link]

Abstract: Group compensation and public announcement of performance are two common aspects of working in groups. We randomly assign these aspects to real-effort tasks. Following task completion and payment, subjects are given an unexpected opportunity to donate to a local charity. Group compensation and public announcement of performance have little effect on work performance but striking spillover effects on subsequent donations. Public announcement of performance doubles the amount donated to charity, and group compensation significantly increases the share donating. The results suggest that interpersonal interactions in the workplace environment may have important spillover effects on prosocial behavior outside of work.

15. Team incentives and leadership (with Daniele Nosenzo and Martin Sefton), Journal of Economic Psychology (2017), vol. 62, pp. 173–185 [Link]

Abstract: We study, experimentally, how two alternative incentive mechanisms affect team performance and how a team chooses between alternative mechanisms. We study a group incentive mechanism (team output is shared equally among team members) and a hierarchical mechanism (team output is allocated by a team leader). We find that output is higher when a leader has the power to allocate output, but this mechanism also generates large differences between earnings of leaders and other team members. When team members can choose how much of team output is to be shared equally and how much is to be allocated by a leader they tend to restrict the leader’s power to distributing less than half of the pie.

14. The Endowment Effect in Games (with Joep Sonnemans), European Economic Review (2017), vol. 94, pp. 240-262 [Link]

Abstract: In a laboratory experiment we study whether the endowment effect exists in a social and strategic context. We employ a within-subjects design whereby participants are asked for their Willingness-to-Accept (WTA) or Willingness-to-Pay (WTP) to play a series of 2x2 games. In the second part of the experiment, we study the endowment effect in lotteries with the same payoffs as the games in the first part. Our findings provide robust evidence for the endowment effect both in games and in lotteries, with the size of the effect actually being larger in games than in lotteries. We also find that the endowment effect can partly be attributed to optimism.

13. Norm Elicitation in Within-Subject Designs: Testing for Order Effects (with Giovanna D'Adda and Daniele Nosenzo), Journal of Behavioral and Experimental Economics (2016), vol. 62, pp. 1-7 [Link]

Abstract: We investigate norms of corruption using the norm-elicitation procedure introduced by Krupka and Weber (2013). We use a within-subject design whereby the norms are elicited from the same subjects who are observed making choices in a bribery game. We test whether the order in which the norm-elicitation task and the bribery game are conducted affects elicited norms and behavior. We find little evidence of order effects in our experiment. We discuss how these results compare with those reported in the existing literature.

12. The Effects of Induced Emotions on Pro-Social Behaviour (with Brit Grosskopf), Journal of Public Economics (2016), vol. 134, pp. 1-8 [Link]

Abstract: Emotions are commonly experienced and expressed in human societies; however, their consequences on economic behaviour have received only limited attention. This paper investigates the effects of induced positive and negative emotions on cooperation and sanctioning behaviour in a one-shot voluntary contributions mechanism game, where personal and social interests are at odds. We concentrate on two specific emotions: anger and happiness. Our findings provide clear evidence that measures of social preferences are sensitive to subjects’ current emotional states. Specifically, angry subjects contribute, on average, less than happy subjects and overall welfare as measured by average net earnings is lower when subjects are in an angry mood. We also find that how punishment is used is affected by moods: angry subjects punish harsher than happy subjects, ceteris paribus. These findings suggest that anger, when induced, can have a negative impact on economic behaviour.

11. The role of gender composition and size of the group in a minimum effort game (with Amalia Di Girolamo), Economics Letters (2015), vol. 137, pp. 168-170 [Link]

Abstract: We report an experiment designed to test for gender differences and group size effects in a repeated minimum effort game. We consider all-male, all-female and mixed gender treatments. We also vary the size of the groups, which can consist either of 3 or 6 members. Our findings indicate significant group size effects but no significant gender differences across treatments.

10. Can priming cooperation increase public good contributions? (with Robert Metcalfe and Nattavudh Powdthavee), Theory and Decision (2015) vol. 79(3), pp. 479-492 [Link]

Abstract: We investigate the effect of priming on pro-social behaviour in a setting where there is a clear financial incentive to free ride. By activating the concept of cooperation among randomly selected individuals, we explore whether it is possible to positively influence people’s voluntary contributions to the public good. Our findings indicate that cooperative priming increases contributions in a one-shot public goods game from approximately 25–36% compared with the non-primed group. The results call for further explorations of the role of priming in economic behaviours in general.

9. Are Happier People Less Judgmental of Other People’s Selfish Behaviors? Laboratory Evidence from Trust and Gift Exchange Games (with Nattavudh Powdthavee), Journal of Behavioral and Experimental Economics (2015), vol. 58, pp. 111-123 [Link]

Abstract: What determines people's moral judgments of selfish behaviors? Here we study whether people's normative views in trust and gift exchange games, which underlie many situations of economic and social significance, are themselves functions of positive emotions. We use experimental survey methods to investigate the moral judgments of impartial observers empirically, and explore whether we could influence subsequent judgments by deliberately making some individuals happier. We find that moral judgments of selfish behaviors in the economic context depend strongly on the behavior of the interaction partner of the judged person, but their relationships are significantly moderated by an increase in happiness for the person making the judgment.

8. Selecting Public Good Institutions: Who Likes to Punish and Reward? (with Julian Jamison), accepted for publication, Southern Economic Journal (2015) vol. 82(2), pp. 501-534 [Link]

Abstract: We study the link between individual attitudes toward uncertainty on the one hand, and preferences over, as well as behavior within, various public goods institutions on the other hand. In particular, we measure individual levels of risk aversion and ambiguity aversion over both gains and losses. We then incentive-compatibly elicit preferences over voluntary contribution mechanisms with and without reward and punishment options. Finally we randomly assign subjects to one of the four institutions and observe repeated play. We find that payoffs are significantly greater when punishment is allowed but that only a small minority of participants prefers such an environment. Somewhat surprisingly, preferences over institutions are generally independent of individual characteristics. On the other hand, institutional preferences, as well as individual characteristics, are significantly predictive of behavior in the public goods game. For instance, risk averse individuals preemptively punish more often when that option is available. This result suggests that when studying social behaviors involving sanctions and rewards, it is important to consider individual attitudes toward risk and uncertainty—although they may not affect the original selection into institutions.

7. Alleviation and Sanctions in Social Dilemma Games, Games (2015), 6(3), 368-380, Special Issue "Experimental Studies of Social Dilemma Games" [Link]

Abstract: This paper reports an experiment which compares behaviour in two punishment regimes: (i) a standard public goods game with punishment in which subjects are given the opportunity to punish other group members (democratic punishment regime) and (ii) a public goods game environment where all group members exogenously experience an automatic reduction of their income (irrespective of their behaviour) and are given the opportunity to alleviate the automatic penalty (undemocratic punishment regime). We employ a within-subjects design where subjects experience both environments and control for order effects by alternating their sequence. Our findings indicate that average contributions and earnings in the undemocratic punishment environment are significantly lower relative to the standard public goods game with punishment. We also observe that in the undemocratic environment average contributions decay over time only when subjects have experienced the standard public goods game with punishment. As a result, alleviation is significantly less when subjects have experienced the standard public goods game with punishment compared to when they do not have such experience. However, the assignment of punishment is robust irrespective of the order in which the games are played.

6. Political Motivations and Electoral Competition: Equilibrium Analysis and Experimental Evidence (with Alejandro Saporiti and Nick Vriend), Games and Economic Behavior (2014), vol. 83, pp. 86-115 [Link]

Abstract: We study both theoretically and experimentally the set of Nash equilibria of a classical one-dimensional election game with two candidates. These candidates are interested in power and ideology, but their weights on these two motives are not necessarily identical. Apart from obtaining the well known median voter result and the two-sided policy differentiation outcome, the paper uncovers the existence of two new equilibrium configurations, called ‘one-sided’ and ‘probabilistic’ policy differentiation, respectively. Our analysis shows how these equilibrium configurations depend on the relative interests in power (resp., ideology) and the uncertainty about votersʼ preferences. The theoretical predictions are supported by the data collected from a laboratory experiment, as we observe convergence to the Nash equilibrium values at the aggregate as well as at the individual levels in all treatments, and the comparative statics effects across treatments are as predicted by the theory.

5. Group Identity and Leading-by-Example (with Daniele Nosenzo), Journal of Economic Psychology (2013), vol. 39, pp. 414-425 [Link]

Abstract: We study the interplay between leading-by-example and group identity in a three-person sequential voluntary contributions game experiment. A common identity between the leader and her two followers is beneficial for cooperation: average contributions are more than 30% higher than in a benchmark treatment where no identity was induced. In two further treatments we study the effects of heterogeneous identities. We find no effect on cooperation when only one of the followers shares the leader’s identity, or when followers share a common identity that differs from that of the leader. We conclude that group identity is an effective but fragile instrument to promote cooperation.

4. Signaling without a common prior: Results on experimental equilibrium selection (with Wieland Müller and Alex Possajennikov), Games and Economic Behavior (2012), vol. 74(1), pp. 102-119. [Link]

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

3. Framing and Free Riding: Emotional Responses and Punishment in Social Dilemma Games (with Robin Cubitt and Simon Gächter), Experimental Economics (2011), vol. 14(2), pp. 254-272. [Link]

Abstract: In this paper, we report an experimental investigation of the effect of framing on social preferences, as revealed in a one-shot linear public goods game. We use two types of indicator to measure social preferences: self-reported emotional responses; and, as a behavioural indicator of disapproval, punishment. Our findings are that, for a given pattern of contributions, neither type of indicator depends on the Give versus Take framing that we manipulate. To this extent, they suggest that the social preferences we observe are robust to framing effects.

2. Moral Judgements in Social Dilemmas: How Bad is Free Riding? (with Robin Cubitt, Simon Gächter and Ruslan Kabalin), Journal of Public Economics (2011), vol. 95(3-4), pp. 253-264. [Link]

Abstract: In the last thirty years, economists and other social scientists have investigated people's normative views on distributive justice. Here we study people's normative views in social dilemmas, which underlie many situations of economic and social significance. Using insights from moral philosophy and psychology we provide an analysis of the morality of free riding. We use experimental survey methods to investigate people's moral judgments empirically. We vary others' contributions, the framing (“give-some” versus “take-some”) and whether contributions are simultaneous or sequential. We find that moral judgments of a free rider depend strongly on others' behaviour; and that failing to give is condemned more strongly than withdrawing all support.

1. Gaining Power through Enlargement: Strategic Foundations and Experimental Evidence (with Maria Montero and Martin Sefton), Games and Economic Behavior (2010), vol. 69(1), pp. 274-292. [Link]

Abstract: Power indices suggest that adding new members to a voting body may affect the balance of power between the original members even if their number of votes and the decision rule remain constant. Some of the original members may actually gain even if voters are bargaining over a fixed budget. We show that this phenomenon can occur as an equilibrium of a non-cooperative bargaining game based on the Baron and Ferejohn (1989) model of legislative bargaining. We implement this game in the laboratory and find that power can be gained by adding new members as the theory predicts.