Different Demographic Cues Yield Inconsistent Conclusions About LLM Personalization and Bias

Manuel Tonneau, Neil Sehgal, Niyati Malhotra, Sharif Kazemi, Victor Orozco-Olvera, Ana Maria Munoz Boudet, Lakshmi Subramanian, Samuel Fraiberger, Sharath Chandra Guntuku, Valentin Hofmann


Abstract
Demographic cue-based evaluation is widely used to study how large language models (LLMs) adapt their responses to signaled demographic attributes within and across groups. This approach typically relies on a single cue (e.g., names) as a proxy for group membership, implicitly treating different cues as interchangeable operationalizations of a single underlying identity-conditioned behavior. We test this assumption in realistic advice-seeking interactions spanning 14.8 million prompts, focusing on race and gender in a U.S. context. We find that cues for the same group induce only partially overlapping changes in model responses, yielding inconsistent conclusions about personalization, while bias conclusions are unstable, with both magnitude and direction of group differences varying across cues. We further show that these inconsistencies reflect differences in cue–group association strength and linguistic features bundled within cues that shape model responses. Together, our findings suggest that demographic conditioning in LLMs is not a cue-invariant category-level parameter but depends fundamentally on how identity is cued, reflecting responses to linguistic signals rather than stable demographic categories. We therefore call for multi-cue, mechanism-aware evaluations as a foundation for robust and interpretable claims about demographic variation in LLM responses.
Anthology ID:
2026.emnlp-main.2118
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
48170–48198
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URL:
https://aclanthology.org/2026.emnlp-main.2118/
DOI:
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Cite (ACL):
Manuel Tonneau, Neil Sehgal, Niyati Malhotra, Sharif Kazemi, Victor Orozco-Olvera, Ana Maria Munoz Boudet, Lakshmi Subramanian, Samuel Fraiberger, Sharath Chandra Guntuku, and Valentin Hofmann. 2026. Different Demographic Cues Yield Inconsistent Conclusions About LLM Personalization and Bias. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 48170–48198, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Different Demographic Cues Yield Inconsistent Conclusions About LLM Personalization and Bias (Tonneau et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.2118.pdf