VISA: Value Injection via Shielded Adaptation for Personalized LLM Alignment

Jiawei Chen, Tianzhuo Yang, Guoxi Zhang, Jiaming Ji, Yaodong Yang, Juntao Dai


Abstract
Personalizing large language models often requires adapting them to new domains, tasks, or user preferences. However, such adaptation can unintentionally shift a model’s value profile, even when the training data is primarily knowledge-oriented. We refer to this failure mode as value drift, a form of value alignment tax that emerges when learning new knowledge interferes with pre-existing alignment. To address this problem, we propose VISA, a modular framework for Value Injection via Shielded Adaptation. VISA keeps the base model as a stable content generator and trains a lightweight Value Rewriter to adjust the value expression of generated responses toward a target value vector. The target is constructed through a Value Detector and an Instruction Translator, while the rewriter is optimized with Group Relative Policy Optimization using rewards for value alignment and semantic consistency. We further construct VCR-45K, a value-conditioned rewriting dataset for evaluating controllable value adaptation. Experiments show that VISA substantially improves semantic preservation over prompting and fine-tuning baselines while maintaining competitive value alignment, enabling low-cost personalized alignment with reduced value drift.
Anthology ID:
2026.emnlp-main.303
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
Note:
Pages:
6973–6999
Language:
URL:
https://aclanthology.org/2026.emnlp-main.303/
DOI:
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Cite (ACL):
Jiawei Chen, Tianzhuo Yang, Guoxi Zhang, Jiaming Ji, Yaodong Yang, and Juntao Dai. 2026. VISA: Value Injection via Shielded Adaptation for Personalized LLM Alignment. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 6973–6999, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
VISA: Value Injection via Shielded Adaptation for Personalized LLM Alignment (Chen et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.303.pdf