DiPer: Disentangled Personal Direction Discovery for Personalized Generation Steering

Muchen Yang, Weinan Gan, Wentao Shi, Chongming Gao, Quanyu Dai, Yichao Wang, Yong Liu, Yangyang Li, Fuli Feng


Abstract
Large Language Model (LLM) personalization aims to adapt generation to individual users by capturing implicit preferences from historical interactions. Steering-based methods offer an inference-efficient solution, but existing work follows a difference-based paradigm that estimates personalized steering directions from representation offsets between contrastive historical examples, thus entangling inherent user preference with preference-agnostic contextual bias. This limitation arises because offset-based estimation uses raw contrastive variation, making the derived direction confounded by contextual bias rather than identifying preference-discriminative variation between user-conditioned and generic behavior. To address this, we propose Disentangled Personal Direction Discovery (DiPer), which formulates personalized steering vector estimation as a discriminative direction discovery problem. DiPer learns layer-wise user-specific directions through supervised metric learning, based on Recursive Feature Machine (CITATION), over historical activations, to discover preference-discriminative directions while suppressing contextual bias. Theoretical analysis and extensive experiments demonstrate DiPer’s efficacy and robustness.
Anthology ID:
2026.findings-emnlp.1865
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
39810–39826
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URL:
https://aclanthology.org/2026.findings-emnlp.1865/
DOI:
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Cite (ACL):
Muchen Yang, Weinan Gan, Wentao Shi, Chongming Gao, Quanyu Dai, Yichao Wang, Yong Liu, Yangyang Li, and Fuli Feng. 2026. DiPer: Disentangled Personal Direction Discovery for Personalized Generation Steering. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 39810–39826, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DiPer: Disentangled Personal Direction Discovery for Personalized Generation Steering (Yang et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.1865.pdf