Humans become more prosocial after nature exposure. We proposed that the prosocial effect pertains to resource (e.g., food, water) and security (e.g., shelter, concealment) features in natural environments. Four studies tested the idea that prosociality changes with variations in environmental resource and security. Study 1 reported that urban greenspace, a resource feature to urban dwellers, predicted more volunteering in low-crime cities, but less so in high-crime cities. Studies 2 and 3 compared prosociality after exposure to natural sceneries in a Resource (high/low) × Security (high/low) design. Participants were more prosocial in the high-resource-high-security and low-resource-low-security conditions. Study 4 compared the four natural environments with two control conditions (urban, shape). It reported that not all natural environments led to higher prosociality, nor did any of them undermine prosociality. The findings supported heterogeneity in nature's prosocial effect. Implications are discussed in relation to urban greening and the evolutionary basis of nature's effect.
Keywords: evolution; nature; prosociality; resource; security.