AI summary · arXiv: 2610.30785v1 · cs.CL

Invisibilization as a Source of Probability Bias in Language Models

Christian Arnold, Ernesto Calvo, Guadalupe Gonzalez, Sebastián Vallejo Vera, Tiago Ventura
Original paper Submitted to arXiv on 22 Oct. 2026 17 pages, 4 figures, 2 tables License: NONEXCLUSIVE-DISTRIB 1.0

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The essentials

Leading language models often refuse to assess reports based on the reporter’s description, producing racial gaps in information use that average-trust audits can miss.

Based on the abstract only: check the details in the original paper.

Question

The paper asks whether attempts to avoid using protected attributes lead language models to disregard potentially valuable information based on who provides it. It examines whether this behavior varies with the reporter’s description and whether an alternative scoring approach reduces the bias.

Method

The authors use a two-urn game with an exact Bayesian answer and test leading models from OpenAI and Anthropic across ten randomized reporter-description configurations, totaling 6,600 sessions. They compare refusal rates and trust judgments, and test a scoring option based on revealed truth over repeated rounds.

Findings

  • Result In the widest reported gap, models declined to assess a Black-described reporter 46% of the time and a white-described reporter 9% of the time.
    See the passage in the paper
    At its widest, models decline a Black-described reporter 46% of the time and a white-described reporter 9%; yet, when they do assess the information, the Black-described reporter receives slightly more trust.
  • Result Among cases where models did assess the report, the Black-described reporter received slightly more trust.
    See the passage in the paper
    At its widest, models decline a Black-described reporter 46% of the time and a white-described reporter 9%; yet, when they do assess the information, the Black-described reporter receives slightly more trust.
  • Authors’ interpretation Comparisons of average trust or only assessed cases can miss the bias arising from refusals.
    See the passage in the paper
    The bias is invisible to audits that compare average trust or look only at assessed cases.
  • Result The reported behavior varied with wording: models invoked race for “Black,” not its Spanish translation “negro,” and never for “Indigenous”; warning instructions worsened the bias.
    See the passage in the paper
    It grows with reasoning effort, follows words rather than categories (models invoke race for "Black" but not for its Spanish translation negro, and never for "Indigenous"), and worsens under warning instructions a practitioner would try first.
  • Result Scoring trust against revealed truth over repeated rounds reduced the racial trust gap below 0.02 in the last rounds in four of five tested configurations.
    See the passage in the paper
    When a model's trust is scored against revealed truth over repeated rounds, it credits identical records equally. In four of five configurations from Anthropic and OpenAI, the racial gap in trust falls below 0.02 by the last rounds.

Limitations

  • The study evaluates models in a two-urn game and does not establish how the findings generalize beyond this task.

Why it matters

The authors argue that refusals can themselves create probability bias, even when audits of average trust suggest little or no disparity. They present scoring based on revealed truth over repeated rounds as an option that reduces the racial gap in trust in most tested configurations.

Written by AI from the paper. Passages are checked word for word against the text we analysed; the rest may contain errors.

AI-generated keywords: language models algorithmic bias refusal behavior racial disparities Bayesian reasoning

Read further

  • Comprehensive Summary
  • Layman's Summary
  • Blog article
  • Original abstract
“Invisibilization as a Source of Probability Bias in Language Models,” by Christian Arnold, Ernesto Calvo, Guadalupe Gonzalez, Sebastián Vallejo Vera, and Tiago Ventura, examines how language models handle information from a person whose report cannot be independently verified. The central question is whether models assess the report consistently across descriptions of its source, or whether they avoid evaluating it when the description includes a protected attribute such as race. This distinction matters because declining to assess information can have consequences. A system may appear not to make a biased judgment while still discounting useful evidence. To investigate this, the authors use a two-urn game with an exact Bayesian answer. They present leading models from OpenAI and Anthropic with a task that requires them to decide how much to trust an unverifiable report. The reporter’s description is randomized across ten configurations, and the study includes 6,600 sessions. This design lets the researchers distinguish between assigning the evidence a level of trust and declining or hedging instead of evaluating it. The abstract reports that models often decline to assess the reporter, and that this behavior varies with the description rather than the evidential content. At the widest reported gap, models decline to assess a Black-described reporter 46% of the time, compared with 9% for a white-described reporter. Yet among cases in which models do assess the information, they assign slightly more trust to the Black-described reporter. As a result, comparing average trust or examining only assessed cases can miss the disparity: it appears in whether a judgment is made at all, not simply in the trust assigned after evaluation. The authors call this pattern “invisibilization,” arguing that refusals can conceal unequal treatment from audits focused on explicit judgments. The reported pattern also depends on how the person is described. The abstract further states that refusal bias increases with reasoning effort and worsens under warning instructions that practitioners might initially try. As a proposed mitigation, the authors introduce a scoring option based on revealed truth across repeated rounds. Under this approach, identical records receive equal credit. In four of the five configurations tested across Anthropic and OpenAI, the racial gap in trust falls below 0.02 by the final rounds. The paper concludes that evaluations of model bias should measure refusals and other forms of non-assessment, rather than focusing only on explicit trust judgments. It also suggests that scoring decisions against outcomes over repeated rounds may reduce disparities in this task. However, only the title, authors, and abstract are available here, so the prompt details, model versions, definitions of refusal and trust, statistical uncertainty, and five configurations cannot be assessed. The evidence is limited to this two-urn task and the model interactions described; the abstract alone does not establish how broadly the findings generalize to other decisions, settings, or populations.

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Weekly letter Presented in "Artificial intelligence this week" of 26 October 2026. Artificial intelligence this week: What changes when AI meets the world

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