AlignDiff: Exploiting Model-Intrinsic Information for Better Preference Data Selection

Peng Lai, He Zhu, Zhiwen Ruan, Dongdong Zhang, Yun Chen, Peng Li, Furu Wei, Yang Liu, Guanhua Chen


Abstract
Aligning large language models with human preferences remains a challenge, primarily due to the critical role of preference data quality in effective alignment. Existing datasets are frequently plagued by inherent noise and distribution shifts, which inherently limit model performance. To bridge this gap, we propose AlignDiff, a preference data filtering framework driven by intrinsic model signals. AlignDiff first identifies samples with clear preferences using both positive and inverse signals, then prioritizes the more challenging samples based on the average negative log-likelihood gap, encouraging the model to learn richer information from them. AlignDiff is evaluated on two widely used model families (LLaMA and Qwen) and three benchmarks widely adopted in the alignment community (AlpacaEval 2.0, Arena-Hard, and MT-Bench). Across all settings, it consistently outperforms seven strong baselines. We conduct comprehensive ablation studies to validate the effectiveness of AlignDiff, and further show that difficulty-based curriculum learning improves model performance.
Anthology ID:
2026.findings-emnlp.85
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
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1734–1755
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.85/
DOI:
Bibkey:
Cite (ACL):
Peng Lai, He Zhu, Zhiwen Ruan, Dongdong Zhang, Yun Chen, Peng Li, Furu Wei, Yang Liu, and Guanhua Chen. 2026. AlignDiff: Exploiting Model-Intrinsic Information for Better Preference Data Selection. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 1734–1755, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
AlignDiff: Exploiting Model-Intrinsic Information for Better Preference Data Selection (Lai et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.85.pdf