Chance neglect in performance judgments

Humans often struggle to incorporate chance information into performance evaluations. Across diverse samples in China and the United States (total N = 1387), we show that people systematically misperceive or ignore chance-level success rates when judging the efficacy of technological practices. Using scenarios where chance performance is objectively known (e.g., ∼50 % success rate for fetal sex prediction), we find that (1) many participants underestimate the success achievable by random guessing, (2) even when they accurately recognize chance-level information, they often fail to use it as a baseline for evaluating expert predictions, and (3) this “chance neglect” is especially pronounced in performance-related judgments. These findings highlight a cognitive bias that may contribute to the persistence of ineffective technologies across societies.