Group vs. individual payments for ecosystem services

A lab-in-the-field experiment testing whether paying a group, versus paying individuals, changes cooperation in shared-resource management — and whether that effect survives once the payments stop.

Design. Participants were randomized into group-payment and individual-payment arms of a common-pool resource game, with a no-payment control. The identification challenge: PES effects on cooperation are routinely confounded by who selects into a scheme in the first place, so treatment assignment — not self-selection — is what does the causal work here.

What I found. The unit of reward mattered more than the presence of a reward. Group payments sustained cooperation after the incentive was removed in a way individual payments did not — consistent with payments building durable group norms rather than just buying compliance for as long as the money lasts.