RVPO:基于方差正则化的风险敏感对齐
当多数RLHF在‘求总分’,这篇Apple论文告诉你得分方差也致命,做安全对齐的人会看到新的损失函数怎么把一致性也纳入训练目标。
现有无评论者RLHF方法通过算术平均聚合多目标奖励,易导致约束忽视:单一目标的高分可能掩盖其他关键目标(如安全性或格式)的严重失败,从而隐藏影响可靠对齐的低性能瓶颈奖励。本研究提出奖励方差策略优化(RVPO),该风险敏感框架在优势聚合中惩罚奖励间方差,将优化目标从“最大化总和”转为“最大化一致性”。分析表明,RVPO能有效识别并提升瓶颈奖励的贡献,在安全性、格式遵循等多目标对齐任务中实现更均衡的策略优化。
Current critic-less RLHF methods aggregate multi-objective rewards via an arithmetic mean, leaving them vulnerable to constraint neglect: high-magnitude success in one objective can numerically offset critical failures in others (e.g., safety or formatting), masking low-performing “bottleneck” rewards vital for reliable multi-objective alignment. We propose Reward-Variance Policy Optimization (RVPO), a risk-sensitive framework that penalizes inter-reward variance during advantage aggregation, shifting the objective from “maximize sum” to “maximize consistency.” We show via Taylor expansion…