arXiv:2512.09212cs.CL2025-12AAAI被引 3

通过检测模型与奖励模型的冲突,提升大模型对齐效果。

Targeting Misalignment: A Conflict-Aware Framework for Reward-Model-based LLM Alignment

  • 将对齐过程视为知识整合,识别模型与奖励模型的分歧点。
  • 在两个任务上验证,即使奖励模型有偏差仍能提升对齐性能。
  • 聚焦高冲突样本获取人工反馈,效率更高且更精准。

基于奖励模型的微调是使大语言模型与人类偏好对齐的核心方法。然而,该方法严重依赖代理奖励模型准确反映预期监督信号,而标注噪声、偏见或覆盖不足常导致这一假设失效,引发模型优化错误信号而非真实人类价值观的问题。本文提出一种新框架,将微调视为知识整合过程,重点检测代理策略与基础模型之间的冲突实例。我们认为,此类冲突往往反映双方共同知识盲区,易导致对齐偏差。为此,我们设计了两种互补度量:局部的代理-策略对齐冲突评分(PACS)和全局的肯德尔τ距离。基于此,提出冲突感知采样的选择性人机反馈算法(SHF-CAS),针对高冲突问答对引入人工反馈,高效优化奖励模型与策略。在两个对齐任务上的实验表明,该方法可显著提升整体对齐性能,即便使用有偏的代理奖励模型。本工作为理解对齐失败提供了新视角,并为大模型训练中的定向优化提供了一条系统性路径。

原文摘要 · Abstract (English)

Reward-model-based fine-tuning is a central paradigm in aligning Large Language Models with human preferences. However, such approaches critically rely on the assumption that proxy reward models accurately reflect intended supervision, a condition often violated due to annotation noise, bias, or limited coverage. This misalignment can lead to undesirable behaviors, where models optimize for flawed signals rather than true human values. In this paper, we investigate a novel framework to identify and mitigate such misalignment by treating the fine-tuning process as a form of knowledge integration. We focus on detecting instances of proxy-policy conflicts, cases where the base model strongly disagrees with the proxy. We argue that such conflicts often signify areas of shared ignorance, where neither the policy nor the reward model possesses sufficient knowledge, making them especially susceptible to misalignment. To this end, we propose two complementary metrics for identifying these conflicts: a localized Proxy-Policy Alignment Conflict Score (PACS) and a global Kendall-Tau Distance measure. Building on this insight, we design an algorithm named Selective Human-in-the-loop Feedback via Conflict-Aware Sampling (SHF-CAS) that targets high-conflict QA pairs for additional feedback, refining both the reward model and policy efficiently. Experiments on two alignment tasks demonstrate that our approach enhances general alignment performance, even when trained with a biased proxy reward. Our work provides a new lens for interpreting alignment failures and offers a principled pathway for targeted refinement in LLM training.

大模型对齐奖励模型人机反馈

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