Unpredictable and competitive cues affect prosocial behaviors and judgments

Why natural selection would favor thoughts or behaviors that benefit others at the cost of oneself (prosociality) in humans is an intriguing question. The present studies explored two kinds of cues representing overarching environmental factors that might affect prosociality: unpredictability, which represents the variability of extrinsic threats, and competition, which represents the relevance of others' performance to one's fitness. In three...