Social Preferences, Beliefs, and the Dynamics of Free Riding in Public Goods Experiments
研究发现，公共品自愿捐款随时间下降的原因是人们倾向于成为不完美的条件合作者，即希望比别人贡献更少，而非信念变化或偏好异质性，这导致即使多数人并非自私，普遍搭便车仍会最终出现。
One lingering puzzle is why voluntary contributions to public goods decline over time in experimental and real-world settings. We show that the decline of cooperation is driven by individual preferences for imperfect conditional cooperation. Many people's desire to contribute less than others, rather than changing beliefs of what others will contribute over time or people's heterogeneity in preferences makes voluntary cooperation fragile. Universal free riding thus eventually emerges, despite the fact that most people are not selfish. (D12, D 83, H41, Z13)