通过融合模型与标注不确定性,显著减少强化学习中的奖励欺骗问题。
Uncertainty-Aware Reward Discounting for Mitigating Reward Hacking

- 用集成模型分歧和标注者差异联合建模两种不确定性
- 在连续控制和离散决策任务中降低93.6%的奖励欺骗
- 适合关注对齐性与鲁棒性的强化学习系统设计者
基于人类反馈的强化学习(RLHF)系统面临双重对齐挑战:学习到的奖励模型对未见状态-动作对存在认知不确定性,而训练所用的人类偏好标注本身也存在不一致、依赖上下文和噪声。现有方法分别处理这些不确定性——认知不确定性用于引导探索,而偏好不确定性则在奖励模型训练时吸收但被丢弃于策略优化阶段。本文提出不确定性感知的奖励折扣机制(UARD),通过集成分歧建模价值估计的认知不确定性,通过标注者变异建模人类偏好的随机不确定性,并利用置信度调节的可靠性过滤器,在策略优化中动态调整奖励权重。我们证明该动态折扣保持贝尔曼算子的压缩性质,保证收敛至唯一不动点,并从信息瓶颈原理提供理论支持。实验表明,相较于DQN、Ensemble-DQN、CQL、CPO、TRPO、SAC、EDAC、SUNRISE和PPO等九种基线,UARD在离散决策与连续控制(MuJoCo)基准上将奖励欺骗事件减少高达93.6%,同时在良好定义的奖励任务上保持竞争力。在10%至30%高斯扰动的标注噪声下,UARD仍维持近零安全违规,而基线表现呈近线性退化。结果表明,将不确定性作为优化目标的主动成分,而非被动诊断信号,是构建更可靠、对齐的强化学习系统的可行路径。
原文摘要 · Abstract (English)
Reinforcement learning from human feedback (RLHF) systems face a compounding alignment challenge: not only are learned reward models uncertain about unseen state-action pairs, but the human preference annotations they are trained on are themselves inconsistent, context-dependent, and noisy. Existing approaches address these uncertainty sources in isolation - epistemic uncertainty is used to guide exploration, while preference uncertainty is absorbed during reward model training but discarded during policy optimization. We introduce Uncertainty-Aware Reward Discounting (UARD), a principled framework that jointly models epistemic uncertainty in value estimation via ensemble disagreement and aleatoric uncertainty in human preference annotations via annotator variability, combining these signals through a confidence-adjusted Reliability Filter that adaptively modulates reward weighting during policy optimization. We prove that this dynamic discounting preserves the contraction property of the Bellman operator, guaranteeing convergence to a unique fixed point, and provide an information-theoretic justification grounded in the Information Bottleneck principle. Empirically, UARD reduces reward hacking incidents by up to 93.6% across discrete decision-making and continuous control benchmarks (MuJoCo) compared to nine baselines including DQN, Ensemble-DQN, CQL, CPO, TRPO, SAC, EDAC, SUNRISE, and PPO, while maintaining competitive task performance on well-specified rewards. Under annotation noise ranging from 10% to 30% Gaussian perturbation, UARD retains near-zero safety violations compared to baselines' near-linear degradation. These results demonstrate that treating uncertainty as an active component of the optimization objective - rather than a passive diagnostic signal - provides a principled pathway toward more reliable and aligned RL systems.
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