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Sprint projectJun 22, 2026Salvador, Brazil

MIPFF: A Framework for Metamorphic Detection of Implicit Social Bias in Brazilian-Portuguese Profile-Scoring Systems

Lucas Teixeira Borges · Team Lucas T Borges

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

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Report: MIPFF: A Framework for Metamorphic Detection of Implicit Social Bias in Brazilian-Portuguese Profile-Scoring Systems

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Automated systems that score and rank job candidates are often assumed to be fairer than humans, yet the language models inside them can carry social bias, and that bias is hard to catch in real, unstructured profiles where demographics are never stated outright. MIPFF (Metamorphic Implicit-Proxy Flagging Framework) audits such a system by rewriting a profile to flip one implicit proxy at a time (a regional, racial, or gender cue) while holding qualifications fixed, scoring the original and the variant repeatedly, and flagging the pair for manual review when the score shift trips any of three statistical indicators (Bias Deviation, a Mann-Whitney test, and Cohen's d). We applied it to four Brazilian-Portuguese-capable models across proxies for communities marginalized in Brazil, finding that average shifts are small but specific candidates can move sharply, and that bias concentrates in an unstated "company-values" criterion. The result is a deployable, human-in-the-loop bias-detection tool for an under-audited language.

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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 most important next step is validation against a real deployed system rather than a simulated one. The gap between "an LLM prompted to act as a screener" and "an actual LLM-based screener in production" is non-trivial: real systems may have system prompts, fine-tuning, retrieval augmentation, or post-processing steps that interact with the bias patterns MIPFF is designed to detect. A collaboration with a company or institution actually using LLM-based screening in Brazil would transform this from a proof-of-concept into a practical tool.

    On the "company values" finding: the observation that bias concentrates in an underspecified vague criterion has a direct governance implication that the paper understates. If organizations must specify what "fit" means before an AI system is deployed to evaluate it, this is actually an auditable design requirement, since you would bot be able to use an AI screener with a vague values criterion. This connects MIPFF directly to procurement regulation and could be spelled out more explicitly.

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  2. Clever piece, and I enjoyed it. The core idea is real: you can't edit a demographic field that unstructured profiles don't have, so you flip the implicit cue and hold qualifications fixed instead. Most audits walk past that missing field. You found the way around it, in Brazilian Portuguese, where almost nobody is looking. What I'd credit most is that you audited your own instrument: 15 runs per profile, three indicators instead of one clean number, and you caught that sabiazinho-4's noise was inflating its raw deviation before it fooled you. Opening with the small aggregate, then the candidate sliding 74 to 68 on Northeastern markers (d ≈ -3.9), is what makes the per-instance case land.

    Where it's thin is proof that a flag means what you want it to. Nothing yet ties a flagged pair to an actually biased decision, and the chain is synthetic all the way down: GPT-written profiles, an LLM playing the screener, one job description. Three fixes: check your flags against a known bias method or some human labels, so a flag is more than "the distributions diverged"; confirm each mutation moved only the proxy and didn't shave off a skill, or you're measuring the rewrite; and run a small batch of real profiles with the STEM job description you float, the cheapest proof it holds outside the sandbox.

    One writing note: your sharpest finding is hiding near the limitations. Bias piling up in "company values," the one criterion you left undefined, splitting the models hard (half the race pairs on gpt-5.4-mini, almost nothing on sabia-3.1), is close to a paper of its own. Put it up front. Good work, and the kind I'd want to see pushed further.

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  3. Great project, please keep with the future work, because there is probably the solution to the problem you are suggestions, specially the use of real profiles could be a great way to test your method

  4. The application of this method of looking at unstructured data, cultural proxies in natural language profiles and individual candidates score shifts in Brazilian Portugese language in particular is novel. The suggestion to use the three statistical indicator rule to flag for when a human supervisor should be involved is also a notable additional layer to the design of the study that other researchers can test to see whether it actually addresses the problems of a "small sample of repeated evaluations". It is also worth re-investigating how the LLMs came up with the stereotypes that the authors accept as the cultural proxies for the replication and expansion of this study.

Cite this project

@misc{borges2026mipff,
  title = {{MIPFF: A Framework for Metamorphic Detection of Implicit Social Bias in Brazilian-Portuguese Profile-Scoring Systems}},
  author = {Lucas Teixeira Borges},
  year = {2026},
  month = jun,
  note = {Submitted to Global South AI Safety Hackathon, an Apart Research Sprint},
  howpublished = {\url{https://apartresearch.com/sprints/projects/mipff-a-framework-for-metamorphic-detection-of-implicit-social-bias-in-brazilianportuguese-profilescoring-systems-ho5q}},
  url = {https://apartresearch.com/sprints/projects/mipff-a-framework-for-metamorphic-detection-of-implicit-social-bias-in-brazilianportuguese-profilescoring-systems-ho5q}
}

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