Voluntary Contribution Experiments Research Articles

Sustaining cooperation in heterogeneous groups

The public goods game has been studied extensively in the lab as the quintessential model of a social dilemma. Several mechanisms have been demonstrated to promote group cooperation in linear voluntary contribution experiments – such as communication, costly punishment, and centralized bonuses and fines. However, lab experiments have largely neglected a central obstacle to efficient public good provision: Individuals typically have different, private demands for consumption, hindering the ability of either a central authority or the group members themselves to calculate and enforce the optimal behavior. I adapt the standard public goods game to incorporate heterogeneous incentives and provide an assessment of each mechanism in this richer environment. I find that baseline cooperation is similar to that in the standard linear game. Sanctions are weak and generally ineffective. Communication, however, does promote cooperation, especially when subjects are given the opportunity to reveal their demand or demand is observable. Finally, a centralized fine/bonus scheme is most effective at increasing contributions, but low demanders must pay a fine in equilibrium.

In broad daylight: Fuller information and higher-order punishment opportunities can promote cooperation

The expectation that non-cooperators will be punished can help to sustain cooperation, but there are competing claims about whether opportunities to engage in higher-order punishment (punishing punishment or failure to punish) help or undermine cooperation in social dilemmas. Varying treatments of a voluntary contribution experiment, we find that availability of higher-order punishment opportunities increases cooperation and efficiency when subjects have full information on the pattern of punishing and its history, when any subject can punish any other, and when the numbers of punishment and of contribution stages are not too unequal.

Leading by example versus leading by words in voluntary contribution experiments

This paper compares different forms of leadership in their ability to improve cooperation in a public goods experiment. Leaders either contribute before the others (leading by example) or make a non-binding pledge before all players contribute simultaneously (leading by words). The exogenously imposed leadership is then compared to an endogenous setting where players can choose if and how they want to lead. The results show that in both settings leading by example has significant positive effects on cooperation while leading by words only has small effects as compared to situations without leadership. However, only few subjects choose to lead by example when they have the choice. The majority choose to lead by words or do not want to lead at all. The results also show that leading by example is associated with an institutional effect (players increase their contributions when they have to lead by example) and a selection effect (players who choose to lead by example are particularly cooperative).

A voluntary contribution experiment with one-way communication and income heterogeneity

One-way communication has been found to increase contributions in linear Voluntary Contribution Mechanisms (VCMs). We confirm the robustness of this result in the presence of income heterogeneity. Our analysis indicates that the communicator directs the members of his group to the highest pay-off that they may attain.

IMMATERIAL REWARDS AND SANCTIONS IN A VOLUNTARY CONTRIBUTION EXPERIMENT

In this article, we compare the causes and effects of immaterial rewards and sanctions on cooperation in a voluntary contribution experiment. It appears that both rewards and sanctions increase contributions (and that rewards are more effective than sanctions) only when subjects interact repeatedly within the same group. The effect is, however, insignificant, which could be due to the higher variance in presence of rewards and sanctions. Furthermore, it is evidenced that rewards have some negative effect on the future contribution for both the imposer and the imposed when the partner matching is applied, but both rewards and sanctions have mainly positive effects under the stranger matching. Thus it seems that the recipient of the feedback takes the message as a reliable external evaluation of her contribution only under the stranger matching protocol when the strategic use of feedback can largely be excluded. (JEL C92, H41)

Leading by words: A voluntary contribution experiment with one-way communication

We use experimental methods to study the power of leading by words. The context is a voluntary contribution mechanism with one-way communication. One group member can send a free-form text message to his fellow players. Contrary to the commonly accepted wisdom that the cooperation-enhancing effect of communication requires the mutual exchange of promises, we find that the introduction of one-way communication increases contributions substantially and decreases their variation. When communication is one-shot, its effect on contribution levels persists over time. Moreover, one-way communication is effective even in the absence of strategic concerns.

Strategic behavior in repeated voluntary contribution experiments

We conduct a repeated VCM (voluntary contribution mechanism) experiment using the strategy method and compare contribution behavior in a partner and a stranger matching in both a cold and a hot setting, where the latter differs from the former by allowing participants to revise their strategies in each round. Irrespective of whether the setting is hot or cold we find that partners provide higher initial contributions than strangers. In the cold setting (without revision possibility) partners contribute more on average but do not react differently to past contributions by others than strangers. In the hot setting the dynamic contribution plans of strangers are somewhat upward-shifted. Furthermore the contributions of partners decrease more strongly than those of strangers over time in a hot setting. The reason for this effect lies in the fact that partners react much more strongly to negative experiences than strangers. Our design and results contribute to explaining the mixed evidence in the literature on partner versus stranger comparisons and allow us to understand under which conditions commitment can be conducive or harmful to achieving and sustaining higher levels of contribution.

Not just babble: Opening the black box of communication in a voluntary contribution experiment

We let subjects in a voluntary contribution experiment make non-binding numerical announcements about their “possible” contributions and, in some treatments, send written promises to contribute specific amounts. We find that announcements were responded to both by others’ announcements and by real play, for example announcements led to costly punishment when found to be misleading. We also find that adding pre-play announcements to treatments with punishment can increase efficiency by letting cost-free warnings substitute for costly punishment. The threat of punishing false announcements and promises helps reduce false signals, but only when promise statements can be sent is the effect sufficient for achieving greater efficiency.

Not Just Babble: Opening the Black Box of Communication in a Voluntary Contribution Experiment

We let subjects in a voluntary contribution experiment make non-binding numerical announcements about their possible contributions and, in some treatments, send written promises to contribute specific amounts. We find that announcements were responded to both by others' announcements and by real play, for example announcements led to costly punishment when found to be misleading. We also find that adding pre-play announcements to treatments with punishment can increase efficiency by letting cost-free warnings substitute for costly punishment. The threat of punishing false announcements and promises helps reduce false signals, but only when promise statements can be sent is the effect sufficient for achieving greater efficiency.

Strategic behavior and learning in repeated voluntary contribution experiments

Voluntary contribution experiments systematically find that contributions decline over time. We use a two-stage voluntary contribution game to investigate whether this decrease is caused by learning or strategic behavior. Using a strategy method we find a robust pattern of declining contributions: contributions in stage 2 are 45 percent lower than in stage 1. Repeating the game five times we find that experience generates a smaller decline in contributions: stage 1 contributions decrease by around 7 percent per game. Finally we find no significant differences between the strategy and direct-response method, which suggests that our results help explain behavior in the latter.

Leading by example with and without exclusion power in voluntary contribution experiments

We examine the effects of leading by example in voluntary contribution experiments. Leadership is implemented by letting one group member contribute to the public good before followers do. Such leadership increases contributions in comparison to the standard voluntary contribution mechanism, especially so when it goes along with authority in the form of granting the leader exclusion power. Whether leadership is fixed or rotating among group members has no significant influence on contributions. Only a minority of groups succeeds in endogenously installing a leader, even though groups with leaders are much more efficient than groups without a leader.

Communication and punishment in voluntary contribution experiments

We compare three forms of communication and punishment as incentives to increase contributions to public goods in laboratory experiments. We find, as in earlier experiments, that face-to-face communication has very strong effects, but surprisingly that verbal communication through a chat room preserving anonymity and excluding facial expression, etc. was almost as efficient. Numerical communication, via computer terminals, had no net effect on contributions or efficiency. Punishment, as in earlier experiments, increased contributions but because of its cost had little net effect on efficiency.

Not Just Babble: A Voluntary Contribution Experiment with Iterative Numerical Messages

When subjects can make non-binding announcements of possible contributions to a public good numerically, there is no effect on average level of contributions in a public goods experiment relative to play without announcements. But a detailed analysis of this experiment shows that pre-play announcements increased the variance of achieved cooperation among groups, leading both to more highly cooperative groups and to more thoroughly uncooperative groups than in a treatment without announcements. We also add a treatment in which subjects can select a statement of (non-binding) to contribute a certain amount and we find that even though subjects were instructed that promise statements were not binding, the ability to issue them significantly increased both contributions and earnings in a treatment that includes costly punishment opportunities, although not in a treatment without punishment.