通过双模型协作过滤噪声偏好,提升大模型对齐的可靠性。
Two Minds Better Than One: Collaborative Reward Modeling for LLM Alignment
- 双奖励模型相互审查数据,动态筛选噪声偏好
- 在40%噪声下,奖励模型性能提升9.94点
- 适用于显式与隐式奖励对齐,适合高可靠性需求场景
奖励模型(RMs)在对齐大语言模型(LLMs)与人类价值观中起关键作用。然而,人类反馈中的噪声偏好会导致奖励误泛化——即模型学习到虚假相关性或过拟合噪声偏好,严重影响模型泛化能力。本文系统分析了偏好对的特征,发现噪声偏好难以被奖励模型拟合,会引发剧烈训练波动和不规则梯度更新。这些特性提示可通过识别并剔除噪声偏好来改进学习。实验证明,使用包含大量噪声的完整数据集训练的策略模型,其表现劣于仅用高质量偏好子集训练的模型。为此,我们提出在线协同奖励建模(CRM)框架,通过同伴评审与课程学习实现稳健偏好学习。CRM维护两个奖励模型,相互审查对方的数据选择;课程学习同步两模型能力,避免差异过大影响评审效果。大量实验表明,CRM显著提升奖励模型泛化能力,在40%极端噪声下,RewardBench得分最高提升9.94分。此外,CRM可无缝扩展至隐式奖励对齐方法,提供一种鲁棒且通用的对齐策略。
原文摘要 · Abstract (English)
Reward models (RMs) play a pivotal role in aligning large language models (LLMs) with human values. However, noisy preferences in human feedback can lead to reward misgeneralization - a phenomenon where reward models learn spurious correlations or overfit to noisy preferences, which poses important challenges to the generalization of RMs. This paper systematically analyzes the characteristics of preference pairs and aims to identify how noisy preferences differ from human-aligned preferences in reward modeling. Our analysis reveals that noisy preferences are difficult for RMs to fit, as they cause sharp training fluctuations and irregular gradient updates. These distinctive dynamics suggest the feasibility of identifying and excluding such noisy preferences. Empirical studies demonstrate that policy LLM optimized with a reward model trained on the full preference dataset, which includes substantial noise, performs worse than the one trained on a subset of exclusively high quality preferences. To address this challenge, we propose an online Collaborative Reward Modeling (CRM) framework to achieve robust preference learning through peer review and curriculum learning. In particular, CRM maintains two RMs that collaboratively filter potential noisy preferences by peer-reviewing each other's data selections. Curriculum learning synchronizes the capabilities of two models, mitigating excessive disparities to promote the utility of peer review. Extensive experiments demonstrate that CRM significantly enhances RM generalization, with up to 9.94 points improvement on RewardBench under an extreme 40\% noise. Moreover, CRM can seamlessly extend to implicit-reward alignment methods, offering a robust and versatile alignment strategy.
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