Overcoming Reward Overoptimization via Adversarial Policy Optimization with Lightweight Uncertainty Estimation
<|reference_start|>Overcoming Reward Overoptimization via Adversarial Policy Optimization with Lightweight Uncertainty Estimation: We introduce Adversarial Policy Optimization (AdvPO), a novel solution to the pervasive issue of reward over-optimization in Reinforcement Learning from Human Feedback (RLHF) for Large Language Models (LLMs). Over-optimization occurs when a reward model serves as an imperfect proxy for human preference, and RL-driven policy optimization erroneously exploits reward inaccuracies. In this paper, we begin by introducing a lightweight way to quantify uncertainties in rewards, relying solely on the last layer embeddings of the reward model, without the need for computationally expensive reward ensembles. AdvPO then addresses a distributionally robust optimization problem centred around the confidence interval of the reward model's predictions for policy improvement. Through comprehensive experiments on the Anthropic HH and TL;DR summarization datasets, we illustrate the efficacy of AdvPO in mitigating the overoptimization issue, consequently resulting in enhanced performance as evaluated through human-assisted evaluation.<|reference_end|>
@article{zhang2024overcoming,
    title={Overcoming Reward Overoptimization via Adversarial Policy Optimization
  with Lightweight Uncertainty Estimation},
    author={Xiaoying Zhang, Jean-Francois Ton, Wei Shen, Hongning Wang, Yang Liu},
    journal={arXiv preprint arXiv:2403.05171},
    year={2024},
    archivePrefix={arXiv},
    eprint={2403.05171},
    primaryClass={cs.LG cs.AI}
}