Klaus Abbink’s research while affiliated with Monash University (Australia) and other places

Communication is one of the most effective devices in promoting team cooperation. However, asymmetric communication sometimes breeds collusion and hurts team efficiency. Here, we present experimental evidence showing that excluding one member from team communication hurts team cooperation; the communicating partners collude in profit allocation against the excluded member, and the latter reacts by exerting less effort. Allowing the partners to reach out to the excluded member partially restores cooperation and fairness in profit allocation, but it does not stop the partners from talking behind that member’s back even when they could have talked publicly. The partners sometimes game the system by tricking the excluded member into contributing but then grabbing all profits for themselves. This paper was accepted by Axel Ockenfels, behavioral economics and decision analysis.

We study escalation and aggression in an experimental first-strike game in which two participants play multiple rounds of a money-earning task. In each round, both players can spend money to accumulate weapons. The player with more weapons can spend money to strike against the other player, which almost totally eliminates the victim's earnings potential and removes their capacity to strike. Weapons can serve as a means of deterrence. In four treatments, we find that deterrence is strengthened if weapon stocking cannot be observed, that a balance of power is effective in maintaining peace, and that mutually beneficial trade decreases the risk of confrontation, but not necessarily the likelihood of costly arms races.

We conduct an experiment to examine gender bias in intra-household decision-making in rural Bangladesh. The experiment mimics a real-life scenario, in which a risky choice with high stakes is offered to either spouse and he/she then has to decide whether to make the decision or transfer it to the other spouse. We then observe the decision-making process under alternative experimental conditions to determine intra-household gender bias. We find that women are more likely to allow their spouses to make decisions than men are. Our findings suggest that women's transfer decisions are driven by asymmetries in both power and perceived financial capabilities.

We employ laboratory experiments to examine the effects of corrupt law enforcement on crime. We embed corruption in a social dilemma where citizens choose whether to obey the law or to break the law and impose a negative externality on others. Police officers observe citizens' behavior and can impose fines on law-breakers or extort bribes from any citizen. We find that the presence of police, even if they are corrupt, substantially reduces crime as compared to a baseline setting without police. Corrupt police officers use bribes in a targeted manner as a substitute for fines to punish law-breakers. We also test the effectiveness of two reward mechanisms aimed at reducing police corruption, both of which are based on society-wide police performance measures and not on the monitoring of individual officers. Both mechanisms make bribery more precisely targeted toward law-breakers, and one of them leads to a moderate reduction in crime.

We study in-group favouritism and out-group discrimination in a multiplayer dictator game in a naturally occuring group setting. An allocator divides a large sum of money among three groups of around 20 recipients each and also to themselves. The groups are supporters of two rival political movements in Thailand and politically neutral subjects. The non-rival out-group acts as a reference point and allows us to measure in-group favouritism and out-group discrimination. A treatment with artificial groups serves as a control. We find both in-group favouritism and out-group discrimination among the naturally occurring groups. In artificial groups, favouritism is observed, but not discrimination. Our results suggest that the two behaviours are not driven by the same motive, and only when groups are in conflict that out-group discrimination is likely to occur.

We introduce the experimental mobbing game. Each player in a group has the option to nominate one of the other players or to nominate no one. If the same person is nominated by all other players, he loses his payoff and the mob gains. We conduct three sets of experiments to study the effects of monetary gains, fear of being mobbed, and different types of focality. In the repeated mobbing game, we find that subjects frequently coordinate on selecting a victim, even for modest gains. Higher gains make mobbing more likely. We find no evidence that fear of becoming the victim explains mobbing. Richer and poorer players are equally focal. Pity plays no role in mobbing decisions. Ingroup members – introduced by colours – are less likely to be victims, and both payoff difference and colour difference serve as strong coordination devices. Commonly employed social preference theories do not explain our findings.

We report a sequential bribery game to disentangle the effect of descriptive social norms and sanctions on bribe offers. Participants who knew that they were interacting with a partner from a group with a majority of corrupt (as opposed to honest) partners offered twice as many bribes. This effect of norms occurred independently of strategic considerations and the possibility of being sanctioned. Indeed, the effect of sanctions was not significant. These findings highlight a causal connection from perceptions of bribery to actual behavior.

In this paper, we study the determinants of inter-groups conflicts, focusing our attention on the role of inequality aversion. First, we experimentally investigate whether inequality is a driving force of inter-group conflicts. Second, we investigate the factors that make preferences for conflict translate into actions. Inter-group conflicts require both coordination and necessary financial material resources. Our experiment consists of a two-stage game. First, subjects play a proportional rent-seeking game to share a prize. In a second stage players can coordinate with the other members of their group to reduce (“burn”) the other group members’ payoff. Treatments differ in the degree of social inequality set between the two groups by attributing to some subjects (the advantaged group) a larger share of the price than other subjects (the disadvantaged group) for the same amount of effort. We observe frequent conflicts, where, as expected, disadvantaged groups “burn” more money than advantaged groups. Surprisingly, however the frequency of conflicts decreases with the degree of inequality. Our data allow us to identify resignation as the driving force behind this phenomenon.