让大模型学会批判性思考,提升回答正确性。
From Faithfulness to Correctness: Generative Reward Models that Think Critically
- 通过句子级思维监督,分步评估答案的忠实性与正确性
- 在开放域问答中显著提升错误句子识别率
- 适合需要高质量推理与事实判断的任务场景
通过可验证奖励的强化学习(RLVR),大语言模型在数学和编程等结果易验证领域取得了显著进展。但在开放域问答等复杂任务中,由于难以验证答案正确性,面临严峻挑战。现实知识的模糊性使得仅依赖逻辑一致性难以可靠评估答案真伪,需具备超越表面一致性的批判性评估能力。现有工作多聚焦于提升忠实性(即与支持文档的语义对齐),但易导致模型过度依赖外部资料,削弱自主判断力。为此,本文提出思维监督奖励模型(TRM),引入句子级思维监督,使奖励模型具备批判性思考能力。给定问题、答案和支撑文档,TRM首先评估每句话对文档的忠实性,再进行推理步骤以判断句子级正确性。通过将奖励建模分解为忠实性、推理、正确性三阶段评估,促使模型批判性地利用内外部知识。实验表明,TRM显著提升错误句子识别能力;将其融入策略优化后,答案正确性与实用性均有显著提升。
原文摘要 · Abstract (English)
Through reinforcement learning with verifiable rewards (RLVR), large language models have achieved substantial progress in domains with easily verifiable outcomes, such as mathematics and coding. However, when applied to more complex tasks like open-domain question answering, RLVR faces significant challenges due to the difficulty of verifying correctness. The nuanced and ambiguous nature of real-world knowledge makes it difficult to reliably evaluate correctness in these settings, necessitating further abilities that extend beyond mere logical consistency to encompass an understanding and assessment of both external and internal knowledge. Recent work has primarily focused on improving faithfulness, defined as semantic alignment with supporting documents, which can cause models to rely excessively on external sources and diminish their capacity for critical assessment. To address this, we propose the Thinking-supervised Reward Model (TRM), which incorporates sentence-level thinking supervision to endow reward models with critical thinking abilities. Given a query, answer, and supporting documents, TRM first assesses the faithfulness of each answer sentence to the supporting documents, and then applies a reasoning step to evaluate sentence-level correctness. By structuring reward modeling as a sequence of faithfulness, reasoning, and correctness evaluations, TRM encourages models to critically assess and leverage both external and internal knowledge. Experiments on reward signals demonstrate that TRM substantially improves the identification of incorrect sentences, and incorporating TRM into policy optimization leads to significant gains in both answer correctness and usefulness.
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