Improving Safety Alignment via Balanced Direct Preference Optimization

Fuente: arXiv
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Main Authors: Zhao, Shiji, Wang, Mengyang, Xiong, Shukun, Chen, Fangzhou, Zhu, Qihui, Ruan, Shouwei, Xiao, Yisong, Duan, Ranjie, Chen, Xun, Wei, XingXing
Format: Preprint
Published: 2026
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author Zhao, Shiji
Wang, Mengyang
Xiong, Shukun
Chen, Fangzhou
Zhu, Qihui
Ruan, Shouwei
Xiao, Yisong
Duan, Ranjie
Chen, Xun
Wei, XingXing
author_facet Zhao, Shiji
Wang, Mengyang
Xiong, Shukun
Chen, Fangzhou
Zhu, Qihui
Ruan, Shouwei
Xiao, Yisong
Duan, Ranjie
Chen, Xun
Wei, XingXing
contents With the rapid development and widespread application of Large Language Models (LLMs), their potential safety risks have attracted widespread attention. Reinforcement Learning from Human Feedback (RLHF) has been adopted to enhance the safety performance of LLMs. As a simple and effective alternative to RLHF, Direct Preference Optimization (DPO) is widely used for safety alignment. However, safety alignment still suffers from severe overfitting, which limits its actual performance. This paper revisits the overfitting phenomenon from the perspective of the model's comprehension of the training data. We find that the Imbalanced Preference Comprehension phenomenon exists between responses in preference pairs, which compromises the model's safety performance. To address this, we propose Balanced Direct Preference Optimization (B-DPO), which adaptively modulates optimization strength between preferred and dispreferred responses based on mutual information. A series of experimental results show that B-DPO can enhance the safety capability while maintaining the competitive general capabilities of LLMs on various mainstream benchmarks compared to state-of-the-art methods. \color{red}{Warning: This paper contains examples of harmful texts, and reader discretion is recommended.
format Preprint
id arxiv_https___arxiv_org_abs_2603_22829
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Improving Safety Alignment via Balanced Direct Preference Optimization
Zhao, Shiji
Wang, Mengyang
Xiong, Shukun
Chen, Fangzhou
Zhu, Qihui
Ruan, Shouwei
Xiao, Yisong
Duan, Ranjie
Chen, Xun
Wei, XingXing
Artificial Intelligence
With the rapid development and widespread application of Large Language Models (LLMs), their potential safety risks have attracted widespread attention. Reinforcement Learning from Human Feedback (RLHF) has been adopted to enhance the safety performance of LLMs. As a simple and effective alternative to RLHF, Direct Preference Optimization (DPO) is widely used for safety alignment. However, safety alignment still suffers from severe overfitting, which limits its actual performance. This paper revisits the overfitting phenomenon from the perspective of the model's comprehension of the training data. We find that the Imbalanced Preference Comprehension phenomenon exists between responses in preference pairs, which compromises the model's safety performance. To address this, we propose Balanced Direct Preference Optimization (B-DPO), which adaptively modulates optimization strength between preferred and dispreferred responses based on mutual information. A series of experimental results show that B-DPO can enhance the safety capability while maintaining the competitive general capabilities of LLMs on various mainstream benchmarks compared to state-of-the-art methods. \color{red}{Warning: This paper contains examples of harmful texts, and reader discretion is recommended.
title Improving Safety Alignment via Balanced Direct Preference Optimization
topic Artificial Intelligence
url https://arxiv.org/abs/2603.22829