Having a stake in the future and perceived population density influence intergenerational cooperation.

Intergenerational common-pool resource games represent a new experimental paradigm in which the current generation's decision to cooperate or defect influences future generations who cannot reciprocate, providing key insights for sustainability science. We combine experimental and theoretical approaches to assess the roles of having a stake in the future (50% chance to pass the resource on to themselves in the next generation) and reminders of the presence of others (exposure to people-chatting sounds) on intergenerational cooperation. We find that, as expected, having a stake in the future increases cooperation with future generations, except when participants are also exposed to people-chatting sounds. We hypothesize that this interaction effect occurs because people-chatting sounds trigger a perception of large group size, which reduces the chance of individuals and their descendants benefiting from the pool in the future, thus reducing cooperation. Our results highlight the context-dependent effect of having a future stake on intergenerational cooperation for resource sustainability, and suggest an area of future work for environmental messaging.