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Sprint projectJun 22, 2026San Francisco

The Shapes of Bias in Spanish-Prompted LLMs and the Debiasing Prompt Scaffolds

Ian Rios-Sialer

Submitted to Global South AI Safety Hackathon. Sprint projects are early-stage work by participants, not Apart Research publications.

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Report: The Shapes of Bias in Spanish-Prompted LLMs and the Debiasing Prompt Scaffolds

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Largelanguagemodelsencodeandamplifyhumansocialbias,andtheharmfallshardestonminoritized groups. Mitigating that harm needs interventions tuned to each social context, yet until recently there was no Spanish-language data to even measure such bias. We characterize bias in Spanish-prompted, open-weight LLMs across model scale, combining behavioral, distributional studies on the new SESGO benchmark, where an item is ambiguous when its text names no specific person (the correct answer is unknown,abstain)anddisambiguated whenitspecifiesagroup. Wereporttwopreliminaryfindings. First, smaller models are more biased: across 12 models abstention accuracy rises with scale and the error split towardthemarginalizedgroupnarrows. Second,scalelowersuncertainty: forkingthechainofthought,the larger Qwen3-14B commitsitsanswer atasingledecisivetokenwhilethe smaller Qwen3-0.6B accretes it gradually. These preliminary results give future LATAM-context interventions, including the debiasing promptscaffoldsweleavetofuturework,amapofwherebiaslives,andwereleasetheevaluationharness.

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How much would this matter for AI safety if it worked? How innovative is it? For scores of 4-5: is this actually new to the field, or replicating recent work?

Scoring guide
  1. 1Negligible. No clear problem addressed, or no meaningful novelty.
  2. 2Limited. Addresses a real problem but with a generic or well-trodden approach. Incremental at best.
  3. 3Moderate. Clear problem with a reasonable approach; some novelty in framing or method beyond routine application of existing tools.
  4. 4Significant. Important problem with an original approach, or identifies a neglected problem area. A valuable contribution others could build on.
  5. 5Exceptional. Tackles a critical AI safety problem with a genuinely novel approach, or opens a new research direction. Clear theory of change. You'd be excited to share this with researchers in the area.

How sound are methodology, implementation, and findings?

Scoring guide
  1. 1Seriously flawed. Methodology broken, results uninterpretable, or implementation doesn't work.
  2. 2Weak. Approach has significant gaps: missing validation, flawed experimental design, or incomplete implementation.
  3. 3Competent. Technically solid given the short duration. Methodology makes sense, results are interpretable, limitations acknowledged, work builds toward clear conclusions.
  4. 4Strong. Thorough methodology with convincing validation. Results clearly support conclusions. Immediately useful for future work.
  5. 5Exceptional. Ambitious scope executed rigorously. Surprising findings, novel methods, or unusually robust validation.

How clearly are work, findings, and impact potential communicated?

Scoring guide
  1. 1Incomprehensible. Cannot determine what the project is actually claiming or doing.
  2. 2Hard to follow. Key information buried, missing, or diluted by excessive length. Significant effort to extract main points.
  3. 3Clear enough. Can understand the problem, approach, and results without undue effort. Core content clearly present: problem, method, findings, limitations.
  4. 4Well presented. Easy to follow, well-structured, appropriate level of detail. Target audience would get it quickly.
  5. 5Exceptionally clear. A pleasure to read. Complex ideas made accessible. Could serve as a model for how to present this type of work.

  1. The main thing I would suggest is testing the findings more broadly so the results feel less dependent on a small number of examples. It would also help to make clearer whether the patterns come from model size, model type, or both.

  2. This is the strongest project I reviewed. It does not feel like a weekend demo, it feels like real research. You tested many models and not only one, and you checked the same result in a few different ways. You also shared your tools and data so other people can repeat it. I looked at the code too and it is a large, serious project that matches the paper. I really liked that you were honest about the weak parts, you even kept one broken run instead of hiding it. Two things to make it better. The small and the big models are also different brands, so it is hard to say if the size or the brand is the real reason for the bias. And the title talks about debiasing prompt scaffolds, but the paper says this part is left for later, so please change the title so it matches what you actually did. Strong work, close to ready for publication.

  3. You measure social bias in Spanish across twelve open models and ask how it shifts with model size. SESGO itself is an existing benchmark. The new work is in the analyses: you check whether trivial reformatting flips a model's answer, and you track when a model locks onto an answer mid-reasoning. Those are fresh angles, and the harness behind them is solid and honest about which findings hold and which are early. The takeaway worth leading with is that smaller, cheaper models are both more biased and easier to flip, which is exactly what people run on a budget. Two of the three studies rest on very few examples, so treat the scale result as firm and the others as promising leads. This maps bias rather than reducing it, so the natural next step is whether these patterns point to a fix.

Cite this project

@misc{riossialer2026shapes,
  title = {{The Shapes of Bias in Spanish-Prompted LLMs and the Debiasing Prompt Scaffolds}},
  author = {Ian Rios-Sialer},
  year = {2026},
  month = jun,
  note = {Submitted to Global South AI Safety Hackathon, an Apart Research Sprint},
  howpublished = {\url{https://apartresearch.com/sprints/projects/the-shapes-of-bias-in-spanishprompted-llms-and-the-debiasing-prompt-scaffolds-zm7h}},
  url = {https://apartresearch.com/sprints/projects/the-shapes-of-bias-in-spanishprompted-llms-and-the-debiasing-prompt-scaffolds-zm7h}
}

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