Experience with anonymous interactions reduces intuitive cooperation

The Social Heuristics Hypothesis claims that cooperation is intuitive because it is positively reinforced in everyday life, where behaviour typically has reputational consequences^1,2. Consequently, participants will cooperate in anonymous laboratory settings unless they either reflect on the one-shot nature of the interaction or learn through experience with such settings that cooperation does not promote self-interest. Experiments reveal that cognitive-processing manipulations (which increase reliance on either intuition or deliberation) indeed affect cooperation³, but may also introduce confounds^4,5. Here, we elide the interpretation issues created by between-subjects designs in showing that people are less cooperative over time in laboratory paradigms in which cooperation cannot promote self-interest, but are just as cooperative over time in paradigms that have the potential to promote self-interest. Contrary to previous findings^6,7, we find that cooperation is equally intuitive for men and women: unilateral giving did not differ across gender at the first study session, and decreased equally for both genders across sessions.