VAGEN: Reinforcing World Model Reasoning for Multi-Turn VLM Agents

Fuente: arXiv
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Autori principali: Wang, Kangrui, Zhang, Pingyue, Wang, Zihan, Gao, Yaning, Li, Linjie, Wang, Qineng, Chen, Hanyang, Wan, Chi, Lu, Yiping, Yang, Zhengyuan, Wang, Lijuan, Krishna, Ranjay, Wu, Jiajun, Fei-Fei, Li, Choi, Yejin, Li, Manling
Natura: Preprint
Pubblicazione: 2025
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author Wang, Kangrui
Zhang, Pingyue
Wang, Zihan
Gao, Yaning
Li, Linjie
Wang, Qineng
Chen, Hanyang
Wan, Chi
Lu, Yiping
Yang, Zhengyuan
Wang, Lijuan
Krishna, Ranjay
Wu, Jiajun
Fei-Fei, Li
Choi, Yejin
Li, Manling
author_facet Wang, Kangrui
Zhang, Pingyue
Wang, Zihan
Gao, Yaning
Li, Linjie
Wang, Qineng
Chen, Hanyang
Wan, Chi
Lu, Yiping
Yang, Zhengyuan
Wang, Lijuan
Krishna, Ranjay
Wu, Jiajun
Fei-Fei, Li
Choi, Yejin
Li, Manling
contents A key challenge in training Vision-Language Model (VLM) agents, compared to Language Model (LLM) agents, lies in the shift from textual states to complex visual observations. This transition introduces partial observability and demands robust world modeling. We ask: Can VLM agents construct internal world models through explicit visual state reasoning? To address this question, we architecturally enforce and reward the agent's reasoning process via reinforcement learning (RL), formulating it as a Partially Observable Markov Decision Process (POMDP). We find that decomposing the agent's reasoning into State Estimation ("what is the current state?") and Transition Modeling ("what comes next?") is critical for success, as demonstrated through five reasoning strategies. Our investigation into how agents represent internal beliefs reveals that the optimal representation is task-dependent: Natural Language excels at capturing semantic relationships in general tasks, while Structured formats are indispensable for precise manipulation and control. Building on these insights, we design a World Modeling Reward that provides dense, turn-level supervision for accurate state prediction, and introduce Bi-Level General Advantage Estimation (Bi-Level GAE) for turn-aware credit assignment. Through this form of visual state reasoning, a 3B-parameter model achieves a score of 0.82 across five diverse agent benchmarks, representing a 3$\times$ improvement over its untrained counterpart (0.21) and outperforming proprietary reasoning models such as GPT-5 (0.75), Gemini 2.5 Pro (0.67) and Claude 4.5 (0.62). All experiments are conducted within our VAGEN framework, a scalable system for training and analyzing multi-turn VLM agents in diverse visual environments. Code and data are publicly available at https://vagen-ai.github.io.
format Preprint
id arxiv_https___arxiv_org_abs_2510_16907
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle VAGEN: Reinforcing World Model Reasoning for Multi-Turn VLM Agents
Wang, Kangrui
Zhang, Pingyue
Wang, Zihan
Gao, Yaning
Li, Linjie
Wang, Qineng
Chen, Hanyang
Wan, Chi
Lu, Yiping
Yang, Zhengyuan
Wang, Lijuan
Krishna, Ranjay
Wu, Jiajun
Fei-Fei, Li
Choi, Yejin
Li, Manling
Artificial Intelligence
Computation and Language
A key challenge in training Vision-Language Model (VLM) agents, compared to Language Model (LLM) agents, lies in the shift from textual states to complex visual observations. This transition introduces partial observability and demands robust world modeling. We ask: Can VLM agents construct internal world models through explicit visual state reasoning? To address this question, we architecturally enforce and reward the agent's reasoning process via reinforcement learning (RL), formulating it as a Partially Observable Markov Decision Process (POMDP). We find that decomposing the agent's reasoning into State Estimation ("what is the current state?") and Transition Modeling ("what comes next?") is critical for success, as demonstrated through five reasoning strategies. Our investigation into how agents represent internal beliefs reveals that the optimal representation is task-dependent: Natural Language excels at capturing semantic relationships in general tasks, while Structured formats are indispensable for precise manipulation and control. Building on these insights, we design a World Modeling Reward that provides dense, turn-level supervision for accurate state prediction, and introduce Bi-Level General Advantage Estimation (Bi-Level GAE) for turn-aware credit assignment. Through this form of visual state reasoning, a 3B-parameter model achieves a score of 0.82 across five diverse agent benchmarks, representing a 3$\times$ improvement over its untrained counterpart (0.21) and outperforming proprietary reasoning models such as GPT-5 (0.75), Gemini 2.5 Pro (0.67) and Claude 4.5 (0.62). All experiments are conducted within our VAGEN framework, a scalable system for training and analyzing multi-turn VLM agents in diverse visual environments. Code and data are publicly available at https://vagen-ai.github.io.
title VAGEN: Reinforcing World Model Reasoning for Multi-Turn VLM Agents
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2510.16907