The Tree Task: An Incentivized, One-shot Decision Task to Measure Pro-environmental Behavior

To help mitigate climate change and its associated costs, behavioral economists need to better understand the determinants of pro-environmental behavior. How can this behavior be measured in the lab or online? This study presents the Tree Task, an incentivized, one-shot task used to measure pro-environmental behavior in the form of tree planting. In the Tree Task, individuals face a trade-off between individual immediate financial rewards and long-term environmental gains. In particular, participants have to decide between spending money to plant trees or keeping the money for themselves. We find that participants’ decisions depend on the costs and environmental impact of a tree. As expected, higher costs lead to fewer planted trees, whereas higher carbon dioxide offsets foster tree planting. The number of trees planted correlates with established self-reports assessing environmental attitudes and intentions, belief in climate change, and values in line with pro-environmental behavior. The Tree Task extends the set of validated tasks measuring incentivized pro-environmental behavior in the lab as a short, vivid, and easy-to-explain task.