FAIR: Balancing Identity-Associated Training Signals to Mitigate Personalization Bias

Anvesh Rao Vijjini, Snigdha Chaturvedi


Abstract
Personalization of LLMs can greatly improve user experience by catering to individual preferences and contexts. However, unnecessary differences in model behavior across users based on their personal information can be undesirable. Such differences introduce personalization bias, leading to inconsistent or unsafe behavior across social attributes such as religion, race, and gender. We introduce (Fairness Aware Imbalance Reduction), a framework for mitigating personalization bias by addressing imbalances in stereotype-related content during preference optimization. includes two variants: _D, which applies data-level intervention based on data augmentation with LLMs, and _T, which incorporates fairness-aware reweighting directly into the optimization objective. We evaluate both variants using multiple personalization bias metrics across diverse identities and models. Across all three LLMs, both methods consistently reduce bias relative to baseline, with up to 20 and 30.1 relative improvement by _D and _T, respectively.
Anthology ID:
2026.findings-aacl.160
Volume:
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3191–3208
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URL:
https://aclanthology.org/2026.findings-aacl.160/
DOI:
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Cite (ACL):
Anvesh Rao Vijjini and Snigdha Chaturvedi. 2026. FAIR: Balancing Identity-Associated Training Signals to Mitigate Personalization Bias. In Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026, pages 3191–3208, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
FAIR: Balancing Identity-Associated Training Signals to Mitigate Personalization Bias (Vijjini & Chaturvedi, Findings 2026)
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https://aclanthology.org/2026.findings-aacl.160.pdf