arXiv:2603.20212cs.CLcs.LG2026-03

用快慢思维融合标量与生成式奖励模型,提升效率与性能。

Fast-Slow Thinking RM: Efficient Integration of Scalar and Generative Reward Models

  • 快慢双思架构:先快速预测得分,复杂时启动链式推理判断。
  • 性能提升1.2%,令牌消耗降低20.8%。
  • 适合追求高效高精度对齐的RLHF应用。

奖励模型(RMs)在通过人类反馈强化学习(RLHF)对齐大语言模型中至关重要。生成式奖励模型(GRMs)虽通过链式思维(CoT)推理实现更优准确率,但计算成本高昂;标量奖励模型(SRMs)虽高效,但在复杂场景下表现有限且适应性差。本文提出快-慢思维奖励模型(F/S-RM),受双重认知理论启发,训练单一模型融合两种奖励范式:以首词预测作为标量评分(快思考),在必要时启用基于链式思维的判断(慢思考)。该模型由双置信度激活机制调控慢思考触发时机。F/S-RM相比当前最优模型实现1.2%相对性能提升,同时减少20.8%的令牌消耗。代码与数据将公开。

原文摘要 · Abstract (English)

Reward models (RMs) are critical for aligning Large Language Models via Reinforcement Learning from Human Feedback (RLHF). While Generative Reward Models (GRMs) achieve superior accuracy through chain-of-thought (CoT) reasoning, they incur substantial computational costs. Conversely, Scalar Reward Models (SRMs) offer efficiency but suffer from limited performance and adaptability in complex scenarios. We introduce Fast-Slow Thinking Reward Models (F/S-RM), a hybrid RM architecture inspired by Dual Process Theory. It trains a single model to integrate two distinct reward paradigms: first-token prediction as a scalar score (fast thinking) and CoT-based judgment (slow thinking), regulated by a dual-confidence activation mechanism that determines when to activate slow thinking. F/S-RM achieves a 1.2% relative performance improvement over state-of-the-art models while reducing token consumption by 20.8%. Code and data will be publicly available.

奖励模型强化学习高效推理

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