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Main Authors: Wang, Peiyao, Xu, Haotian, Vesdapunt, Noranart, Hou, Rui, Zhang, Jingyi, Ling, Haibin, Obiednikov, Oleksandr, Zhou, Ning, Fu, Kah Kuen
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.25942
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author Wang, Peiyao
Xu, Haotian
Vesdapunt, Noranart
Hou, Rui
Zhang, Jingyi
Ling, Haibin
Obiednikov, Oleksandr
Zhou, Ning
Fu, Kah Kuen
author_facet Wang, Peiyao
Xu, Haotian
Vesdapunt, Noranart
Hou, Rui
Zhang, Jingyi
Ling, Haibin
Obiednikov, Oleksandr
Zhou, Ning
Fu, Kah Kuen
contents Multi-modal Large Language Models (MLLMs) show promise in video understanding. However, their reasoning often suffers from thinking drift and weak temporal comprehension, even when enhanced by Reinforcement Learning (RL) techniques like Group Relative Policy Optimization (GRPO). Moreover, existing RL methods usually depend on Supervised Fine-Tuning (SFT), which requires costly Chain-of-Thought (CoT) annotation and multi-stage training, and enforces fixed reasoning paths, limiting MLLMs' ability to generalize and potentially inducing bias. To overcome these limitations, we introduce Summary-Driven Reinforcement Learning (SDRL), a novel single-stage RL framework that obviates the need for SFT by utilizing a Structured CoT format: Summarize -> Think -> Answer. SDRL introduces two self-supervised mechanisms integrated into the GRPO objective: 1) Consistency of Vision Knowledge (CVK) enforces factual grounding by reducing KL divergence among generated summaries; and 2) Dynamic Variety of Reasoning (DVR) promotes exploration by dynamically modulating thinking diversity based on group accuracy. This novel integration effectively balances alignment and exploration, supervising both the final answer and the reasoning process. Our method achieves state-of-the-art performance on seven public VideoQA datasets.
format Preprint
id arxiv_https___arxiv_org_abs_2603_25942
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reinforcing Structured Chain-of-Thought for Video Understanding
Wang, Peiyao
Xu, Haotian
Vesdapunt, Noranart
Hou, Rui
Zhang, Jingyi
Ling, Haibin
Obiednikov, Oleksandr
Zhou, Ning
Fu, Kah Kuen
Computer Vision and Pattern Recognition
Artificial Intelligence
Multi-modal Large Language Models (MLLMs) show promise in video understanding. However, their reasoning often suffers from thinking drift and weak temporal comprehension, even when enhanced by Reinforcement Learning (RL) techniques like Group Relative Policy Optimization (GRPO). Moreover, existing RL methods usually depend on Supervised Fine-Tuning (SFT), which requires costly Chain-of-Thought (CoT) annotation and multi-stage training, and enforces fixed reasoning paths, limiting MLLMs' ability to generalize and potentially inducing bias. To overcome these limitations, we introduce Summary-Driven Reinforcement Learning (SDRL), a novel single-stage RL framework that obviates the need for SFT by utilizing a Structured CoT format: Summarize -> Think -> Answer. SDRL introduces two self-supervised mechanisms integrated into the GRPO objective: 1) Consistency of Vision Knowledge (CVK) enforces factual grounding by reducing KL divergence among generated summaries; and 2) Dynamic Variety of Reasoning (DVR) promotes exploration by dynamically modulating thinking diversity based on group accuracy. This novel integration effectively balances alignment and exploration, supervising both the final answer and the reasoning process. Our method achieves state-of-the-art performance on seven public VideoQA datasets.
title Reinforcing Structured Chain-of-Thought for Video Understanding
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2603.25942