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.