arXiv:2505.22653cs.CL2025-05被引 13

用噪声奖励训练大模型推理,发现过程提示比答案正确更重要。

The Climb Carves Wisdom Deeper Than the Summit: On the Noisy Rewards in Learning to Reason

  • 用关键推理句作为奖励信号,不验证答案对错
  • 40%奖励翻转下仍达72%数学准确率,接近无噪声效果
  • 适合提升模型推理能力的后训练场景

近期关于大语言模型通过强化学习进行推理的后训练研究,多聚焦于可精确验证的任务,如解数学题。本文研究了更贴近真实场景的奖励噪声影响。发现大模型对大幅奖励噪声具有强鲁棒性:在数学任务中手动翻转40%的奖励输出,Qwen-2.5-7B模型仍能快速收敛,数学准确率从5%提升至72%,接近使用无噪声奖励训练的75%。令人意外的是,仅基于关键推理短语(如“首先,我需要”)的奖励(即推理模式奖励,RPR),无需验证答案正确性,模型在数学任务上即可达到超70%准确率,与严格验证奖励相当。结合RPR与噪声奖励模型,可校准噪声、减少误判,显著提升开放任务表现。结果表明,应重视预训练阶段的基础推理能力,为后训练提供新思路。代码已开源。

原文摘要 · Abstract (English)

Recent studies on post-training large language models (LLMs) for reasoning through reinforcement learning (RL) typically focus on tasks that can be accurately verified and rewarded, such as solving math problems. In contrast, our research investigates the impact of reward noise, a more practical consideration for real-world scenarios involving the post-training of LLMs using reward models. We found that LLMs demonstrate strong robustness to substantial reward noise. For example, manually flipping 40% of the reward function's outputs in math tasks still allows a Qwen-2.5-7B model to achieve rapid convergence, improving its performance on math tasks from 5% to 72%, compared to the 75% accuracy achieved by a model trained with noiseless rewards. Surprisingly, by only rewarding the appearance of key reasoning phrases (namely reasoning pattern reward, RPR), such as ``first, I need to''-without verifying the correctness of answers, the model achieved peak downstream performance (over 70% accuracy for Qwen-2.5-7B) comparable to models trained with strict correctness verification and accurate rewards. Recognizing the importance of the reasoning process over the final results, we combined RPR with noisy reward models. RPR helped calibrate the noisy reward models, mitigating potential false negatives and enhancing the LLM's performance on open-ended tasks. These findings suggest the importance of improving models' foundational abilities during the pre-training phase while providing insights for advancing post-training techniques. Our code and scripts are available at https://github.com/trestad/Noisy-Rewards-in-Learning-to-Reason.

推理增强强化学习奖励噪声大模型训练

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