ReasonAct: Progressive Training for Fine-Grained Video Reasoning in Small Models

Fuente: arXiv
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Autori principali: Liu, Jiaxin, Kang, Zhaolu
Natura: Preprint
Pubblicazione: 2025
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author Liu, Jiaxin
Kang, Zhaolu
author_facet Liu, Jiaxin
Kang, Zhaolu
contents While recent multimodal models have shown progress in vision-language tasks, small-scale variants still struggle with the fine-grained temporal reasoning required for video understanding. We introduce ReasonAct, a method that enhances video reasoning in smaller models through a three-stage training process: first building a foundation with text-only reasoning, then fine-tuning on video, and finally refining with temporal-aware reinforcement learning. We build upon Temporal Group Relative Policy Optimization (T-GRPO) by incorporating temporal consistency modeling into policy optimization. We also propose a biomechanically-motivated sub-action decomposition mechanism that provides graduated rewards for constituent action phases. Through experiments on HMDB51, UCF-101, and Kinetics-400, our 3B-parameter model achieves 67.2%, 94.1%, and 78.9% accuracy respectively, demonstrating improvements of 17.9, 15.8, and 12.3 points over baselines. Ablation studies validate that our progressive training enables smaller models to achieve competitive video reasoning performance while maintaining computational efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01533
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle ReasonAct: Progressive Training for Fine-Grained Video Reasoning in Small Models
Liu, Jiaxin
Kang, Zhaolu
Computer Vision and Pattern Recognition
While recent multimodal models have shown progress in vision-language tasks, small-scale variants still struggle with the fine-grained temporal reasoning required for video understanding. We introduce ReasonAct, a method that enhances video reasoning in smaller models through a three-stage training process: first building a foundation with text-only reasoning, then fine-tuning on video, and finally refining with temporal-aware reinforcement learning. We build upon Temporal Group Relative Policy Optimization (T-GRPO) by incorporating temporal consistency modeling into policy optimization. We also propose a biomechanically-motivated sub-action decomposition mechanism that provides graduated rewards for constituent action phases. Through experiments on HMDB51, UCF-101, and Kinetics-400, our 3B-parameter model achieves 67.2%, 94.1%, and 78.9% accuracy respectively, demonstrating improvements of 17.9, 15.8, and 12.3 points over baselines. Ablation studies validate that our progressive training enables smaller models to achieve competitive video reasoning performance while maintaining computational efficiency.
title ReasonAct: Progressive Training for Fine-Grained Video Reasoning in Small Models
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2508.01533