Second-Order Zero-Sum Misbeliefs: People Overestimate Others’ Zero-Sum Beliefs

Across 12 empirical studies (N_total = 2,615), this research systematically examined the stable tendency for individuals to overestimate others’ zero-sum beliefs, along with its underlying psychological mechanisms and behavioral consequences. Studies 1–3 and Supplementary Studies 1–4, using diverse experimental designs and measures, consistently showed that people tend to overestimate others’ zero-sum beliefs at both explicit and implicit levels. Studies 4–5, through surveys and experiments, provided converging evidence that construing others at a high construal level—as purely self-interested agents—serves as a key psychological mechanism driving this overestimation. Study 6 and Supplementary Studies 5–6 demonstrated that overestimating others’ zero-sum beliefs significantly reduced cooperative behavior, both in abstract game contexts and in more everyday settings. These findings enrich researchers’ understanding of the illusory nature of zero-sum beliefs and suggest that interventions based on the social norms approach may help correct this overestimation and foster cooperation.