Mitigating Overthinking through Reasoning Shaping
Authors: name: Feifan Song, name: Shaohang Wei, name: Bofei Gao, name: Yejie Wang, name: Wen Luo, name: Wei Li, name: Linli Yao, name: Weimin Xiong, name: Liang Chen, name: Tianyu Liu, name: Houfeng Wang

Large reasoning models (LRMs) boosted by Reinforcement Learning from Verifier
Reward (RLVR) have shown great power in problem solving, yet they often cause
overthinking: excessive, meandering reasoning that inflates computational cost.
Prior designs of penalization in RLVR manage to reduce token consumption while
often harming model performance, which arises from the oversimplicity of
token-level supervision. In this paper, we argue that the granularity of
supervision plays a crucial role in balancing efficiency and accuracy, and
propose Group Relative Segment Penalization (GRSP), a step-level method to
regularize reasoning. Since preliminary analyses show that reasoning segments
are strongly correlated with token consumption and model performance, we design
a length-aware weighting mechanism across segment clusters. Extensive
experiments demonstrate that GRSP achieves superior token efficiency without
heavily compromising accuracy, especially the advantages with harder problems.
Moreover, GRSP stabilizes RL training and scales effectively across model
sizes.