When superstition outperforms truth: Belief transmission, sacrifice, and cooperation under environmental uncertainty

We report results from an intergenerational experiment investigating how prosocial beliefs, whether accurate or false, emerge, spread, and support cooperation under environmental uncertainty (N=448, university students). In a repeated public goods game with randomly determined but ambiguously framed payoff shocks, participants often formed superstitious beliefs linking generosity to rewards. Compared to accurate beliefs, these superstitious beliefs, when transmitted to the next generation and internalized, led to greater cooperation and facilitated group formation via voluntary sacrifice. Individuals who held such beliefs were more likely to sacrifice and self-organize into high-functioning groups, achieving the highest levels of public good provision. These findings illustrate how culturally transmitted beliefs, even when empirically false, can stabilize cooperation by shaping shared expectations and enabling costly commitment.