VRPRM: Process Reward Modeling via Visual Reasoning

arXiv:2508.03556v5 Announce Type: replace Abstract: Process Reward Models (PRMs) provide fine-grained supervision over intermediate reasoning steps, yet most existing models lack long-range reasoning and deep thinking capabilities. Although prior work has introduced Chain-of-Thought (CoT) to reward models, the high annotation cost of CoT-PRM still limits its scalability. To address these challenges, we propose the Visual Reasoning Process Reward Model (VRPRM) and design a label-efficient two-stage training strategy. Experimental results demonstrate that with only 5.5K CoT-PRM supervised step labels and 40K non-CoT PRM reinforcement learning training examples, VRPRM achieves a macro F1 score of 69.18 on VisualProcessBench, outperforming VisualPRM-8B, a non-thinking PRM trained on 400K examples, by 7.00 points. In Best-of-N evaluation, VRPRM-RL brings absolute Overall improvements of 21.77, 23.42, and 23.12 points on InternVL2.5-8B, 26B, and 38B policies, respectively, with a maximum relative improvement of 59.0\%.