Powering up with indirect reciprocity in a large-scale field experiment

Abstract

A defining aspect of human cooperation is the use of sophisticated indirect reciprocity. We observe others, talk about others, and act accordingly. We help those who help others, and we cooperate expecting that others will cooperate in return. Indirect reciprocity is based on reputation, which spreads by communication. A crucial aspect of indirect reciprocity is observability: reputation effects can support cooperation as long as peoples' actions can be observed by others. In evolutionary models of indirect reciprocity, natural selection favors cooperation when observability is sufficiently high. Complimenting this theoretical work are experiments where observability promotes cooperation among small groups playing games in the laboratory. Until now, however, there has been little evidence of observability's power to promote large-scale cooperation in real world settings. Here we provide such evidence using a field study involving 2413 subjects. We collaborated with a utility company to study participation in a program designed to prevent blackouts. We show that observability triples participation in this public goods game. The effect is over four times larger than offering a $25 monetary incentive, the company's previous policy. Furthermore, as predicted by indirect reciprocity, we provide evidence that reputational concerns are driving our observability effect. In sum, we show how indirect reciprocity can be harnessed to increase cooperation in a relevant, real-world public goods game.

Keywords: evolutionary game theory; experimental economics.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Indirect reciprocity can support contributions to public goods, as depicted here. In indirect reciprocity, my behavior toward you depends on how you have behaved toward both myself and others. This process occurs in three stages. First, people engage in a public goods game (cooperators in blue and defectors in red). Peoples’ behavior is observed, both by other players and third parties. Second, information about this behavior can spread from person to person. Based on the information received, peoples’ opinions about the players are updated. Third, as a result, public goods cooperators will receive cooperation in future interactions whereas defectors will be denied cooperation, defected upon, or punished. Thus, indirect reciprocity creates an incentive to contribute to public goods and can promote the evolution of cooperation.

Fig. 2.

We solicited 1,408 customers of a major electric utility for participation in a program designed to prevent blackouts. Residents signed up for the program on sheets posted in a communal area near their home, usually by a shared mailbox kiosk. We varied whether residents’ neighbors could tell who signed up for the program: publicly posted sheets required residents to print their name and unit number (observable treatment) or only a code that does not reveal their identity (anonymous treatment). Observability tripled participation in the program.

Fig. 3.

Observability increased participation more in settings where reputational concerns matter more. (A) Observability increased participation more in apartment buildings where residents are more likely to interact with their neighbors in public spaces and sign-up sheets were typically posted in especially conspicuous locations, compared with row houses or individual homes, where neighbors are less likely to interact and sign-up sheets were less easily visible by others. (B) Similarly, observability increased participation more among those who own their homes/apartments relative to those who rent because renters are more transient and therefore likely to be less invested in long-term relationships with their neighbors.

Fig. 4.

We solicited an additional 1,005 customers with exactly the same treatment as described above, except that the informational materials they received were stripped of any language that framed the blackout prevention program as a public good. The effect of observability was dramatically reduced among subjects who did not receive the public good framing.