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Research reveals that large language models exhibit “invisibility” bias: the rejection rate for evaluating information about Black describers reaches as high as 46%.
An empirical study published on October 24, 2026, on arXiv (paper ID 2610.30785v1) found that mainstream large language models from OpenAI and Anthropic exhibit a significant “invisibility” bias in trust assessment tasks—specifically, they systematically refuse to evaluate information when prompts contain protected attributes (such as “Black”), rather than basing their decisions on the quality of evidence; this bias is difficult to detect using conventional auditing methods.
Why it mattersThis study employs a rigorously designed two-urn Bayesian decision experiment, encompassing 6,600 sessions and 10 descriptive configurations. It is the first to quantify the cost of model‑driven rejection behavior triggered by identity labels and reveals its counterintuitive characteristics: rejection rates vary dramatically (46% for Black describers vs. 9% for White describers), yet once evaluated, Black describers actually receive slightly higher trust; moreover, bias intensifies with increasing reasoning depth, relies on specific vocabulary rather than semantics, and worsens under warning instructions—findings that carry direct implications for AI fairness assessment and alignment practices.