Disclosing Group Members' Identities Reduces Cooperation in an Artefactual Public Goods Field Experiment.

Social dilemmas in the real world, such as pollution and the extraction of resources, often differ regarding the visibility of involved actors and their behavior. While publicly disclosing individual decisions in social dilemmas is known to increase cooperation, little is known about whether revealing individual identities specifically makes a difference. This study uses an artefactual public good field experiment conducted in rural Namibia with 144 villagers, who are randomly assigned to one of two experimental conditions: one in which group members' identities are not disclosed and one in which they are. Individual contributions to the public good remain private in both cases, so the only difference lies in whether participants can see who their group members are. In addition, the experiment's setting in village communities entails pre-existing social ties between participants, which likely amplify potential effects that revealing identities can have on cooperation and allow investigating the role of group composition, such as the share of friends and family members. Results, somewhat unexpectedly, show that contributions to the public good are significantly higher when group members cannot identify one another - a finding that can be explained by several, not necessarily mutually exclusive, mechanisms. Exploratory analyses further reveal that contributions in the identified condition are distinctly lower when group members are socially distant from each other. Although overall variability of contributions does not differ across the two experimental conditions, decisions are more homogenous within groups and more heterogeneous between groups when identities are disclosed.