NIKOS NIKIFORAKIS

Journal Publications

36. Normative conflict and the gender gap in cooperation

Nikos Nikiforakis, Ernesto Reuben and Robert Stueber (2024)

Economics Letters (in press). 

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Abstract

A normative conflict arises when individuals derive different benefits from cooperation. We analyze experimental data from three published studies to investigate the impact of normative conflict on the cooperative behavior of men and women. We find that women exhibit significantly lower levels of cooperation in the presence of normative conflict. We observe no significant gender differences in cooperation in the absence of normative conflict.  

35. Experimental evidence shows that ulterior motive attribution drives counter-punishment

Manu Munoz and Nikos Nikiforakis (2023)

Journal of Economic Science Association 9, 193–206.

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34. Higher socioeconomic status does not predict decreased prosocial behavior in a field experiment

James Andreoni, Nikos Nikiforakis and Jan Stoop (2021)

Nature Communications 12, 4266

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Abstract

Does higher socioeconomic status predict decreased prosocial behavior? Methodological issues such as the reliance of survey studies on self-reported measures of prosociality, the insufficient control of relative incentives in experiments, and the use of non-random samples, have prevented researchers from ruling out that there is a negative association between socioeconomic status (SES) and prosociality. Here, we present results from a field experiment on the willingness of unaware individuals of different SES to undertake an effortful prosocial task—returning a misdelivered letter. Specifically, using the rental or sale value of homes as indicators of SES, we randomly selected households of high and low SES and misdelivered envelopes to them. Despite controlling for numerous covariates and performing a series of ancillary tests, we fail to find any evidence that higher SES predicts decreased prosocial behavior. Instead, we find that misdelivered letters are substantially more likely to be returned from high rather than low SES households. 

33. Predicting social tipping and norm change in controlled experiments

James Andreoni, Nikos Nikiforakis and Simon Siegenthaler (2021)

Proceedings of the National Academy of the Sciences 118(16)

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Abstract

The ability to predict when societies will replace one social norm for another can have significant implications for welfare, especially when norms are detrimental. A popular theory poses that the pressure to conform to social norms creates tipping thresholds which, once passed, propel societies toward an alternative state. Predicting when societies will reach a tipping threshold, however, has been a major challenge because of the lack of experimental data for evaluating competing models. We present evidence from a large-scale laboratory experiment designed to test the theoretical predictions of a threshold model for social tipping and norm change. In our setting, societal preferences change gradually, forcing individuals to weigh the benefit from deviating from the norm against the cost from not conforming to the behavior of others. We show that the model correctly predicts in 96% of instances when a society will succeed or fail to abandon a detrimental norm. Strikingly, we observe widespread persistence of detrimental norms even when individuals determine the cost for nonconformity themselves as they set the latter too high. Interventions that facilitate a common understanding of the benefits from change help most societies abandon detrimental norms. We also show that instigators of change tend to be more risk tolerant and to dislike conformity more. Our findings demonstrate the value of threshold models for understanding social tipping in a broad range of social settings and for designing policies to promote welfare.

32. Covenants before the swords: The limits to efficient cooperation in heterogeneous groups

Christian Koch, Nikos Nikiforakis and Charles Noussair (2021)

Journal of Economic Behavior and Organization 188, 307-321

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Abstract

When agents derive heterogeneous benefits from cooperation, a tension between efficiency and equality often arises. This tension can impede agents’ ability to cooperate efficiently. We design a laboratory experiment, in which we investigate the capacity of communication and punishment, separately and jointly, to promote cooperation in such an environment. Our results reveal that cooperation and earnings are significantly greater when both communication and punishment (a sword) are possible than when only one is available. Both cooperation levels and earnings, however, still fall substantially below the maximum possible. The reason is that groups establish covenants, i.e. mutual contribution agreements, that tend to strike a compromise between efficiency and equality. The timing of communication is critical. A history of sanctioning substantially reduces the probability that groups subsequently establish a covenant. Overall, our findings indicate not only the benefits of early communication, but also some limits to efficient cooperation in heterogeneous groups.

31. The ghost of institutions past: History as an obstacle to fighting tax evasion

Aaron Kamm, Christian Koch and Nikos Nikiforakis (2021)

European Economic Review 132, 103641

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Abstract

Can a history of evasion affect tax compliance after a major institutional reform? We address this question in a novel laboratory experiment varying the quality of past and present institutions. We find that past institutions continue to exert considerable influence on individuals’ expectations about others’ compliance even after a major, common-knowledge institutional change. Consequently, we observe low compliance in good-quality institutions when there is a history of evasion, but high compliance when there is no such history. These findings suggest that history should not be ignored as it is in traditional models of compliance: the higher evasion has been historically, the stronger incentives may need to be to overcome the “ghost of institutions past”. We show that a society-wide poll in which individuals express their attitudes toward compliance can help break the link with the past. 

30. Managerial bonuses and subordinate mistreatment

Nikos Nikiforakis, Oechssler Joerg and Anwar Shah (2019)

European Economic Review 119, 509-525 

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Abstract

Can performance bonuses increase the likelihood that managers coerce their subordinates into exerting high levels of effort when doing so promotes neither efficiency nor equity? We consider a laboratory setting in which managers compete to obtain a large bonus at the end of the experiment and the probability of obtaining it depends partly on the effort exerted by the subordinates. We find that managers are more than twice as likely to punish subordinates exerting “fair” levels of effort if they compete for individual bonuses than when there are no bonuses. This is not the case when they compete for pooled bonuses – giving managers discretionary power over how to share them with their subordinates – as most subordinates willingly exert maximal effort. A model in which individuals are assumed to care about equity captures subordinates’ behavior well. Managers’ willingness to coerce subordinates into exerting unfairly high levels of effort, on the other hand, cannot be readily accounted for by any of the existing models of social preferences.

29. James Andreoni and the quest for others in our utility functions

Muñoz-Herrera Manuel and Nikos Nikiforakis (2019)

Journal of Public Economic Theory 21, 804–811 

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Abstract

Over the past 30 years, James Andreoni has produced a body of work like few others in public economics. Motivated by a personal need to understand the determinants of prosocial behavior, and by offering a rare blend of insights from formal theory, controlled experiments, and field data, Andreoni has succeeded in elucidating the broader relevance of prosocial motives and their far-reaching economic implications. This article offers an overview of his work on prosociality, highlighting some of his seminal contributions and placing them in a historical context. We argue that James Andreoni has had a unique role in the quest to ensure that others have a place in our utility functions. 

28. Surveillance cues do not enhance altruistic behavior among strangers in the field

Erik Koornneef, Aurelie Dariel, Iffat Elbarazi, Ahmed Alsuwaidi, Paul Robben and Nikos Nikiforakis (2018)

PLoS ONE 13(8) 

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Abstract

The degree of altruistic behavior among strangers is an evolutionary puzzle. A prominent explanation is the evolutionary legacy hypothesis according to which an evolved reciprocity-based psychology affects behavior even when reciprocity is impossible, i.e., altruistic behavior in such instances is maladaptive. Empirical support for this explanation comes from laboratory experiments showing that surveillance cues, e.g., photographs of watching eyes, increase altruistic behavior. A competing interpretation for this evidence, however, is that the cues signal the experimenter’s expectations and participants, aware of being monitored, intentionally behave more altruistically to boost their reputation. Here we report the first results from a field experiment on the topic in which participants are unaware they are being monitored and reciprocity is precluded. The experiment investigates the impact of surveillance cues on a textbook example of altruistic behavior—hand hygiene prior to treating a ‘patient’. We find no evidence surveillance cues affect hand hygiene, despite using different measures of hand-hygiene quality and cues that have been previously shown to be effective. We argue that surveillance cues may have an effect only when participants have reasons to believe they are actually monitored. Thus they cannot support claims altruistic behavior between strangers is maladaptive. 

27. Emirati women do not shy away from competition: Evidence from a patriarchal society in transition

Aurelie Dariel, Curtis Kephart, Nikos Nikiforakis and Christina Zenker (2017) 

Journal of the Economic Science Association 3(2), 121-136

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Abstract

We explore gender attitudes towards competition in the United Arab Emirates—a traditionally patriarchal society which in recent times has adopted numerous policies to empower women and promote their role in the labor force. The experimental treatments vary whether individuals compete in single-sex or mixedsex groups. In contrast to previous studies, women in our sample are not less willing to compete than men. In fact, once we control for individual performance, Emirati women are more likely to select into competition. Our analysis shows that neither women nor men shy away from competition, and both compete more than what would be optimal in monetary terms as the fraction of men in their group increases. 

26. Normative conflict and the limits of self-governance in heterogeneous populations

Lata Gangadharan, Nikos Nikiforakis and Marie-Claire Villeval (2017) 

European Economic Review 100, 143–156

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Abstract

Mechanisms to overcome social dilemmas provide incentives to maximize efficiency. However, often – such as when agents are heterogeneous – there is a trade-off between efficiency and equality – a normative conflict – which is overlooked. Agents’ concerns for equality in such instances can limit the ability of mechanisms to promote efficiency. We provide evidence for this from a public good experiment using a simple mechanism allowing individuals to communicate periodically with other group members and reward them for their actions. We show that, in homogeneous populations – where there is no conflict between efficiency and equality – the mechanism permits groups to obtain maximum efficiency. This is not the case in heterogeneous populations despite the fact that individuals could use rewards to resolve the normative conflict. Although almost all heterogeneous groups agree to follow specific contribution rules with positive contributions, most of them either prioritize equality over efficiency or strike a compromise between the two. These findings suggest normative conflict can be difficult to overcome, imposing limits on the ability of heterogeneous populations to reach efficient outcomes through self-governance. 

25. Altruistic punishment does not increase with the severity of norm violations in the field 

Loukas Balafoutas, Nikos Nikiforakis and Bettina Rockenbach (2016) 

Nature Communications 7, 13327 

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Abstract

The degree of human cooperation among strangers is a major evolutionary puzzle. A prominent explanation is that cooperation is maintained because many individuals have a predisposition to punish those violating group-beneficial norms. A critical condition for cooperation to evolve in evolutionary models is that punishment increases with the severity of the violation. Here we present evidence from a field experiment with real-life interactions that, unlike in lab experiments, altruistic punishment does not increase with the severity of the violation, regardless of whether it is direct (confronting a violator) or indirect (withholding help). We also document growing concerns for counter-punishment as the severity of the violation increases, indicating that the marginal cost of direct punishment increases with the severity of violations. The evidence suggests that altruistic punishment may not provide appropriate incentives to deter large violations. Our findings thus offer a rationale for the emergence of formal institutions for promoting large-scale cooperation among strangers. 

24. Coordination with third-party externalities 

James Bland and Nikos Nikiforakis (2015)

European Economic Review 80, 1–15

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Abstract

When agents face coordination problems their choices often impose externalities on third parties. If an agent cares about them or believes others do, they can affect equilibrium selection. We present evidence from lab experiments showing that changes in the size and the sign of third-party externalities have a significant impact on tacit coordination. Decision makers are more willing to incur a cost to try to avoid imposing a large negative externality on a third party, than they are to avoid a small negative externality or to generate a large positive externality. However, when decision-makers' incentives are at odds with the interests of third parties, many of them appear to ignore third-party externalities even if they are large in magnitude, and ignoring them implies substantial earning inequalities and reductions in group earnings. Individuals revealed to be other-regarding in a non-strategic allocation task often behave as-if selfish when trying to coordinate. We discuss explanations for our findings. 

23. In the long run we are all dead: On the benefits of peer punishment in rich environments

Dirk Engelmann and Nikos Nikiforakis (2015)

Social Choice and Welfare 45(3), 561-577

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Abstract

We investigate whether peer punishment is an efficient mechanism for enforcing cooperation in an experiment with a long time horizon. Previous evidence suggests that the costs of peer punishment can be outweighed by the benefits of higher cooperation if (i) there is a sufficiently long time horizon and (ii) punishment cannot be avenged. However, in most instances in daily life, when individuals interact for an extended period of time, punishment can be retaliated. We use a design that imposes minimal restrictions on who can punish whom or when, and allows participants to employ a wide range of punishment strategies including retaliation of punishment. Similar to previous research, we find that, when punishment cannot be avenged, peer punishment leads to higher earnings relative to a baseline treatment without any punishment opportunities. However, in the more general setting, we find no evidence of group earnings increasing systematically or significantly over time relative to the baseline treatment. Our results raise questions under what conditions peer punishment can be an efficient mechanism for enforcing cooperation. 

22. Direct and indirect punishment among strangers in the field 

Loukas Balafoutas, Nikos Nikiforakis and Bettina Rockenbach (2014) 

Proceedings of the National Academy of Sciences 111(45), 15924–15927

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Abstract

Many interactions in modern human societies are among strangers. Explaining cooperation in such interactions is challenging. The two most prominent explanations critically depend on individuals’ willingness to punish defectors: In models of direct punishment, individuals punish antisocial behavior at a personal cost, whereas in models of indirect reciprocity, they punish indirectly by withholding rewards. We investigate these competing explanations in a field experiment with real-life interactions among strangers. We find clear evidence of both direct and indirect punishment. Direct punishment is not rewarded by strangers and, in line with models of indirect reciprocity, is crowded out by indirect punishment opportunities. The existence of direct and indirect punishment in daily life indicates the importance of both means for understanding the evolution of cooperation. 

21. Third-party punishment and counter-punishment in one-shot interactions 

Loukas Balafoutas, Grechenig Kristoffel and Nikos Nikiforakis (2014) 

Economics Letters 122(2), 308-310

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Abstract

This paper presents experimental evidence from a simple three-person game showing that many individuals are willing to avenge third-party punishment in one-shot interactions. The threat of counter-punishment has a large negative effect on the willingness of third parties to punish selfish behavior. In spite of this, the extent of selfish behavior is identical to that in a treatment without counter-punishment opportunities. We discuss explanations for this puzzling finding. 

20. Cooperators and reciprocators: A within-subject analysis of pro-social behavior

Aurelie Dariel and Nikos Nikiforakis (2014) 

Economics Letters 122(2), 163-166

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Abstract

We perform a within-subject analysis of pro-social behavior in the public-good and gift-exchange game. We find that participants classified as cooperators in the public-good game tend to reciprocate higher wages in the gift-exchange game with higher levels of effort. Non-cooperators do not exhibit such tendency. Both types offer similar wages. 

19. Hierarchy, coercion and exploitation: An experimental analysis

Nikos Nikiforakis, Joerg Oechssler and Anwar Shah (2014) 

Journal of Economic Behavior and Organization 97, 155–168

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Abstract

The power to coerce workers is important for the efficient operation of hierarchically structured organizations. However, this power can also be used by managers to exploit their subordinates for their own benefit. We examine the relationship between the power to coerce and exploitation in a laboratory experiment where a senior and a junior player interact repeatedly for a finite number of periods. We find that senior players try repeatedly to use their power to exploit junior workers. These attempts are successful only when junior workers have incomplete information about how their effort impacts on the earnings of senior players, but not when they have complete information. Evidence from an incentive-compatible questionnaire indicates that the social acceptability of exploitation depends on whether the junior worker can detect she is being exploited. We also show how a history of exploitation affects future interactions. 

18. Mixing the carrots with the sticks: Third party punishment and reward [lead article]

Nikos Nikiforakis and Helen Mitchell (2014) 

Experimental Economics 17(1), 1-23

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Abstract

While the opportunity to punish selfish and reward generous behavior coexist in many instances in daily life, in most laboratory studies, the demand for punishment and reward are studied separately from one another. This paper presents the results from an experiment measuring the demand for reward and punishment by ‘unaffected’ third parties, separately and jointly. We find that the demand for costly punishment is substantially lower when individuals are also given the ability to reward. Similarly, the demand for costly reward is lower when individuals can also punish. The evidence indicates the reason for this is that costly punishment and reward are not only used to alter the material payoff of others as assumed by recent economic models, but also as a signal of disapproval and approval of others’ actions, respectively. When the opportunity exists, subjects often choose to withhold reward as a form of costless punishment, and to withhold punishment as a form of costless reward. We conclude that restricting the available options to punishing (rewarding) only, may lead to an increase in the demand for costly punishment (reward). 

17. Recursive contracts, firm longevity and rat races: Experimental evidence

Peter Bardsley, Nisvan Erkal , Nikos Nikiforakis and Tom Wilkening (2013) 

European Economic Review 61, 217-231

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Abstract

This paper reports the results from a laboratory experiment which investigates the structure of contracts that emerge in overlapping-generation firms where future ownership is a perquisite of employment. Workers in the young generation are offered employment contracts designed by the firms' owners who belong to the old generation. When old, employed workers are granted ownership rights as long as the firm continues to operate. In line with theoretical predictions, the results indicate that as firm longevity increases, the recursive nature of the contracts leads to a rat race characterized by low wages, high effort levels, and rent dissipation. These results have important implications for the optimal management of long-lived firms such as partnerships. 

16. Is there selection bias in laboratory experiments? The case of social and risk preferences

Blair L. Cleave, Nikos Nikiforakis and Robert Slonim (2013) 

Experimental Economics 16(3), 372-382

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Abstract

Laboratory experiments are frequently used to examine the nature of individuals’ social and risk preferences and inform economic theory. However, it is unknown whether the preferences of volunteer participants are representative of the population from which the participants are drawn, or whether they differ due to selection bias. To answer this question, we measured the preferences of 1,173 students in a classroom experiment using a trust game and a lottery choice task. Separately, we invited all students to participate in a laboratory experiment using common recruitment procedures. To evaluate whether there is selection bias, we compare the social and risk preferences of students who eventually participated in a laboratory experiment to those who did not, and find that they do not differ significantly. However, we also find that people who sent less in a trust game were more likely to participate in a laboratory experiment, and discuss possible explanations for this behavior. 

15. Social comparisons and reference group formation: Some experimental evidence

Ian McDonald, Nikos Nikiforakis, Nilss Olekalns and Hugh Sibly (2013) 

Games and Economic Behavior 79, 75-89

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Abstract

We experimentally investigate reference group formation and the impact of social comparisons in a three-player ultimatum game. The players compete in a real-effort task for the role of the proposer. The role of the responder is randomly allocated to one of the other two participants. The third participant, the non-responder, receives a fixed payment – our treatment variable – and makes no decision. Knowing the size of this payment, the proposer makes a take-it-or-leave-offer to the responder. Most responders appear to ignore the non-responder when the payment the latter receives is low, but not when it is high. As a result, the existence of a non-responder and the payment they receive has a pronounced effect on bargaining outcomes and increases overall rejection rates. We present a simple model in which agents select the members of their reference group strategically to reduce the extent of cognitive dissonance they experience. The model produces results consistent with our experimental findings. 

14. Norm enforcement in the city: A natural field experiment 

Loukas Balafoutas and Nikos Nikiforakis (2012) 

European Economic Review 56(8), 1773-1785

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Abstract

Extensive evidence from laboratory experiments indicates that many individuals are willing to use costly punishment to enforce social norms, even in one-shot interactions. However, there appears to be little evidence in the literature of such behavior in the field. We study the propensity to punish norm violators in a natural field experiment conducted in the main subway station in Athens, Greece. The large number of passengers ensures that strategic motives for punishing are minimized. We study violations of two distinct efficiency-enhancing social norms. In line with laboratory evidence, we find that individuals punish norm violators. However, these individuals are a minority. Men are more likely than women to punish violators, while the decision to punish is unaffected by the violator's height and gender. Interestingly, we find that violations of the better known of the two norms are substantially less likely to trigger punishment. We present additional evidence from two surveys providing insights into the determinants of norm enforcement. 

13. Normative conflict and feuds: The limits of self-enforcement

Nikos Nikiforakis, Charles Noussair and Tom Wilkening (2012) 

Journal of Public Economics 96(9-10), 797-807

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Abstract

A normative conflict arises when multiple plausible rules exist, specifying how one ought to behave in a given situation. In such cases, enforcing one normative rule can lead to a sequence of mutual retaliatory sanctions, which we refer to as a feud. We investigate the hypothesis that normative conflict enhances the likelihood of a feud in a public-good experiment. Normative conflict in our experiment arises from the fact that individuals derive different benefits from the public good. We find that punishment is much more likely to trigger counter-punishment and start a feud when there is a normative conflict, than it is in a setting in which all individuals derive the same benefit from the public good and no such conflict exists. While the possibility of a feud sustains cooperation, the cost of feuding fully offsets the efficiency gains from increased cooperation. Our results point to an important limitation of self-enforcement mechanisms. 

12. Perfect and imperfect real-time monitoring in a minimum-effort game

Cary Deck and Nikos Nikiforakis (2012)

Experimental Economics 15(1), 71-88

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Abstract

This paper presents the results from a minimum-effort game in which individuals can observe the choices of others in real time. We find that under perfect monitoring almost all groups coordinate at the payoff-dominant equilibrium. However, when individuals can only observe the actions of their immediate neighbors in a circle network, monitoring improves neither coordination nor efficiency relative to a baseline treatment without real-time monitoring. We argue that the inefficacy of imperfect monitoring is due to information uncertainty, that is, uncertainty about the correct interpretation of a neighbor’s actions. Information uncertainty prevents individuals from inferring safely that their group has managed to coordinate from the available information. 

11. Altruistic punishment: What field data can (and cannot) demonstrate

Nikos Nikiforakis (2012) 

Behavioral and Brain Sciences 35(1), 32-33 

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Abstract

The rarity of altruistic punishment in small-scale societies should not be interpreted as evidence that altruistic punishment is not an important determinant of cooperation in general. While it is essential to collect field data on altruistic punishment, this kind of data has limitations. Laboratory experiments can help shed light on the role of altruistic punishment “in the wild.” 

10. Relative earnings and giving in a real effort experiment 

Nisvan Erkal, Lata Gangadharan and Nikos Nikiforakis (2011) 

American Economic Review 101(7): 3330-3348

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Abstract

This paper investigates the relationship between relative earnings and giving in a two-stage, real-effort experiment. In the first stage, four players compete in a tournament that determines their earnings. In the second stage, they decide whether to make a transfer to one or more of their group members. Our main finding is that those ranked first are significantly less likely to give than those ranked second. This difference disappears if individuals learn about the second stage after earning their income or if earnings are randomly determined. This suggests that our main finding is driven by selection based on other-regarding preferences.

9. Altruistic punishment and the threat of feuds 

Nikos Nikiforakis and Dirk Engelmann (2011) 

Journal of Economic Behavior and Organization 78(3), 319-332

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Abstract

Altruistic punishment may promote cooperation, but can also lead to costly feuds. We examine how the threat of feuds affects individuals’ willingness to engage in altruistic punishment in a public good experiment in which the number of stages is determined by participants’ actions. The design imposes minimal restrictions on who can punish whom and when, and therefore allows participants to use a range of punishment strategies. We find that participants recognize the threat of feuds and respond to it by employing strategies that prevent their breakout. When feuds can span several periods, the extent of altruistic punishment is greatly reduced. This leads to progressively lower levels of cooperation and earnings relative to a baseline treatment where punishment cannot be avenged. 

8. Can real-effort investments inhibit the convergence of experimental markets?

Timothy Cason, Lata Gangadharan and Nikos Nikiforakis (2010) 

International Journal of Industrial Organization 29(1), 97-103

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Abstract

Evidence shows that real-effort investments can affect bilateral bargaining outcomes. This paper investigates whether similar investments can inhibit equilibrium convergence of experimental markets. In one treatment, sellers' relative effort affects the allocation of production costs, but a random productivity shock ensures that the allocation is not necessarily equitable. In another treatment, sellers' effort increases the buyers' valuation of a good. We find that effort investments have a short-lived impact on trading behavior when sellers' effort benefits buyers, but no effect when effort determines cost allocation. Efficiency rates are high and do not differ across treatments. 

7. Experimental economics

Nikos Nikiforakis (2010) 

Australian Economic Review 43(3), 337-345

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Abstract

Experimental economics is a branch of economics that uses controlled experiments to explore the predictive power of theories, evaluate behavioural assumptions, investigate behavioural regularities and test the implementation of policies. It is one of the fastest growing areas of economics (Oswald 2010).

The development of an experimental methodology in economics is recent relative to other disciplines such as physics and psychology. Although informal experiments were conducted as early as in the eighteenth century (see Bernoulli 1738), the results from the first formal economic experiment appeared in an article by Edward Chamberlin in 1948. After half a century of continuous growth in the number of economic experiments, in 2002, Vernon Smith, a participant in Chamberlin's experiment, was awarded the Nobel Prize ‘for establishing laboratory experiments as a tool for empirical economics analysis’ (Nobel Announcement 2002).

This article is an introduction to experimental economics aimed primarily at students and scholars with little or no prior knowledge on the topic. The next section discusses why controlled experiments are a valuable tool in economics and proceeds to present lab and field experiments, provide examples of experiments, and address some of the common criticisms regarding laboratory experiments.

6. Feedback, punishment and cooperation in public good experiments

Nikos Nikiforakis (2010)

Games and Economic Behavior 68, 689 -702 

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Abstract

A number of studies have shown that peer punishment can sustain cooperation in public good games. This paper shows that the format used to give subjects feedback is critical for the efficacy of punishment. Providing subjects with information about the earnings of their peers leads to significantly less cooperation and lower efficiency compared to a treatment in which subjects receive information about the contributions of their peers. This is despite the fact that the feedback format does not affect incentives. The data suggest that this happens because the feedback format acts as a coordination device which influences the contribution standards that groups establish. 

5. Asymmetric enforcement of cooperation in a social dilemma

Nikos Nikiforakis, Hans-Theo Normann and Brian Wallace (2010)

Southern Economic Journal 76, 638 - 659

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Abstract

We use a public-good experiment to analyze behavior in a decentralized asymmetric punishment institution. The institution is asymmetric in the sense that players differ in the effectiveness of their punishment. At the aggregate level, we observe remarkable similarities between outcomes in asymmetric and symmetric punishment institutions. Controlling for the average punishment effectiveness of the institutions, we find that asymmetric punishment institutions are as effective in fostering cooperation and are as efficient as symmetric institutions. At the individual level, we find that players with higher punishment effectiveness contribute similar amounts to the public account but have higher earnings and punish more than their weak counterparts. 

4. Does the size of the action set matter for cooperation?

 Lata Gangadharan and Nikos Nikiforakis (2009)

Economics Letters 104, 115-117

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Abstract

We use the voluntary contribution mechanism to investigate whether smaller action sets lead to higher cooperation rates. We find that this is the case for groups of four players.

3. A comparative statics analysis of punishment in public good experiments

Nikos Nikiforakis and Hans-Theo Normann (2008)

Experimental Economics 11, 358-369

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Abstract

This paper provides a comparative-statics analysis of punishment in public-good experiments. We vary the effectiveness of punishment, that is, the factor by which punishment reduces the punished player’s income. The data show that contributions increase monotonically in punishment effectiveness. High effectiveness leads to near complete cooperation and welfare improvements. Below a certain threshold, however, punishment cannot prevent the decay of cooperation. In these cases, punishment opportunities reduce welfare. The results suggest that the experimenter’s choice of the punishment effectiveness is of great importance for the experimental outcome. 

2. Punishment and counter-punishment in public good games: Can we really govern ourselves?

Nikos Nikiforakis (2008) 

Journal of Public Economics 92, 91-112

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Abstract

A number of experimental studies have shown that the opportunity to punish anti-social behavior increases cooperation levels when agents face a social dilemma. Using a public good experiment, I show that in the presence of counter-punishment opportunities cooperators are less willing to punish free riders. As a result, cooperation breaks down and groups have lower earnings in comparison to a treatment without punishments where free riding is predominant. Approximately one quarter of all punishments are retaliated. Counter-punishments appear to be driven partly by strategic considerations and partly by a desire to reciprocate punishments.

1. Vertical cross-shareholding: Theory and experimental evidence

Werner Güth, Nikos Nikiforakis and Hans-Theo Normann (2007) 

International Journal of Industrial Organization 25, 69-89 

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Abstract

This paper analyzes vertical cross-shareholding, that is, the mutual holding of a minority of shares between vertically related firms. First, we explore the issue in a game-theoretic model and show that cross-shareholding is sufficient to obtain efficient outcomes. We then test the model's predictions in an experiment. Theory predicts the seller decisions accurately but the buyer decisions only to a small extent. Buyers are more likely to agree on cross-shareholding than sellers in an attempt to avoid the winner's curse. Cross-shareholding occurs more frequently than predicted, and it increases the likelihood of trade.