Token-weighted Direct Preference Optimization with Attention

Chengyu Huang, Zhuohang Li, Sheng-Yen Chou, Claire Cardie


Abstract
Direct Preference Optimization (DPO) aligns Large Language Models with human preferences without the need for a separate reward model. However, DPO treats all tokens in responses equally, neglecting the differing importance of individual tokens. Existing token-level PO methods compute the token weights using either token-position-based heuristic functions or probability estimates given by a separately trained model, which lacks robustness and incurs extra training cost. In contrast, we propose Token-weighted DPO (TwDPO)—a novel training objective grounded on token-weighted RL—and AttentionPO—an instantiation of TwDPO that uses attention from the LLM itself to estimate token weights. AttentionPO prompts the LLM to serve as a pairwise judge and check where the model attends when comparing the responses. This design makes AttentionPO content-aware, adjusting weights based on response content, and efficient, incurring only two extra forward passes per example. Experiment results show that AttentionPO significantly improves performance on AlpacaEval, MT-Bench, and ArenaHard, surpassing existing Preference Optimization methods.
Anthology ID:
2026.emnlp-main.823
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:
19125–19145
Language:
URL:
https://aclanthology.org/2026.emnlp-main.823/
DOI:
Bibkey:
Cite (ACL):
Chengyu Huang, Zhuohang Li, Sheng-Yen Chou, and Claire Cardie. 2026. Token-weighted Direct Preference Optimization with Attention. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 19125–19145, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Token-weighted Direct Preference Optimization with Attention (Huang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.823.pdf