Dialect vs Demographics: Quantifying LLM Bias from Implicit Linguistic Signals vs. Explicit User Profiles
Paper · 2026 · Irti Haq and Belen Saldias
Summary
LLMs are known to treat users worse when they state membership in a vulnerable group. This paper asks whether the trigger is the stated identity or the way identity shows up in language. The authors ran a 2×3×4 factorial experiment. Task content was held fixed while two cues were varied independently: an explicit self-description (Black, Singaporean, White) and a dialect instruction (AAVE, Singlish, Standard English). They used 2,219 BOLD prompts across four sensitive domains, giving over 24,000 responses from Gemma-3-12B and Qwen-3-VL-8B. Responses were scored for refusal, BERTScore against Wikipedia-derived references, and Relative Negative Regard. Mixed-effects models then separated the effect of each cue from prompt difficulty. The results point opposite ways. Explicit labels, especially for Black users, made Gemma refuse more and lowered similarity to the references. Dialect cues pushed refusals close to zero and slightly raised similarity, but they also yielded less sanitized, more negative content, particularly on politics and religion. The authors read this as evidence that safety alignment keys on explicit words and generalizes poorly to implicit signals.
Key points
- Design: 2 models × 3 identities × 4 domains (Gender, Race, Religion, Politics), with 2,219 BOLD prompts and over 24,000 responses. Analysis used generalized linear mixed-effects models with prompt text as a random effect.
- Refusal detection: a keyword heuristic was checked by hand on 504 responses, with precision 1.000 and recall 0.985.
- Refusal analysis covers Gemma-3-12B only: Qwen-3-VL-8B almost never refused. The authors treat Qwen as a sign that these disparities come from a particular safety regimen rather than from LLMs in general.
- Refusals depend heavily on content: the prompt random-effect σ was 10.02 for refusal, against 0.00 for BERTScore and 0.03 for regard. Refused outputs were not scored further, which creates survivorship bias.
- Limitations acknowledged:
- Dialect text was injected synthetically, not written by native speakers.
- Prompting was one-shot only.
- Gender (male) and occupation were held constant.
- Quality was judged by automated proxies.
Interesting ideas
- I1. Keep the content of a request fixed and toggle the "who says it" signal and the "how it is said" signal as separate factors, so any change in output can be traced to one cue
- I2. Distinguish identity that is declared outright from identity that can only be inferred from style; systems may respond to the first and miss the second entirely
- I3. Score each output against several references and keep the best match, since a short prompt can have many valid continuations
- I4. Before trusting a cheap rule-based detector, audit a few hundred cases by hand and report precision and recall
- I5. Watch for survivorship bias: if failed or refused items are dropped before scoring, the hardest items vanish and quality looks better than it is
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (learn): build paired evaluation sets where only the register or dialect of a sentence changes, as a negative control. The frames and answers produced should stay identical, and any drift points to a brittle stage.
- I2 (frames): prag could record speaker-signaled attributes (explicit self-description versus stylistic cues) as separate, traceable evidence. Later steps would then cite which signal they relied on.
- I3 (answer): when grading Mova's free-text answers on fables or school tests, compare against a set of acceptable answers rather than one gold string. This avoids penalizing valid alternatives.
- I4 (learn): self-induced repair rules and silver-data filters could each carry a small, manually checked audit with precision and recall attached, so their reliability is explicit.
- I5 (learn): log items where a parser or reader gave up and report them alongside the scores. This keeps difficult sentences from silently leaving the evaluation pool.
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksSocial Sciences · 1,772 worksSafety Research · 543 works
🧭 Topics 1Research subjects and languages the work is about.Language models & pretraining · 3,320 works
Cite
Cite as Irti Haq and Belen Saldias. 2026. Dialect vs Demographics: Quantifying LLM Bias from Implicit Linguistic Signals vs. Explicit User Profiles. arXiv:2604.21152.
@misc{haq2026dialect,
title = {{Dialect vs Demographics: Quantifying LLM Bias from Implicit Linguistic Signals vs. Explicit User Profiles}},
author = {Irti Haq and Belen Saldias},
year = {2026},
doi = {10.48550/arxiv.2604.21152},
eprint = {2604.21152},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2604.21152}
}References
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