Enhancing Multi-Modal LLMs Reasoning via Difficulty-Aware Group Normalization

Fuente: arXiv
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Hauptverfasser: Li, Jinghan, Fang, Junfeng, Lu, Jinda, Wang, Yuan, Guo, Xiaoyan, Zhang, Tianyu, Wang, Xiang, He, Xiangnan
Format: Preprint
Veröffentlicht: 2026
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author Li, Jinghan
Fang, Junfeng
Lu, Jinda
Wang, Yuan
Guo, Xiaoyan
Zhang, Tianyu
Wang, Xiang
He, Xiangnan
author_facet Li, Jinghan
Fang, Junfeng
Lu, Jinda
Wang, Yuan
Guo, Xiaoyan
Zhang, Tianyu
Wang, Xiang
He, Xiangnan
contents Reinforcement Learning with Verifiable Rewards (RLVR) and Group Relative Policy Optimization (GRPO) have significantly advanced the reasoning capabilities of large language models. Extending these methods to multimodal settings, however, faces a critical challenge: the instability of std-based normalization, which is easily distorted by extreme samples with nearly positive or negative rewards. Unlike pure-text LLMs, multimodal models are particularly sensitive to such distortions, as both perceptual and reasoning errors influence their responses. To address this, we characterize each sample by its difficulty, defined through perceptual complexity (measured via visual entropy) and reasoning uncertainty (captured by model confidence). Building on this characterization, we propose difficulty-aware group normalization (Durian), which re-groups samples by difficulty levels and shares the std within each group. Our approach preserves GRPO's intra-group distinctions while eliminating sensitivity to extreme cases, yielding significant performance gains across multiple multimodal reasoning benchmarks.
format Preprint
id arxiv_https___arxiv_org_abs_2602_21743
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Enhancing Multi-Modal LLMs Reasoning via Difficulty-Aware Group Normalization
Li, Jinghan
Fang, Junfeng
Lu, Jinda
Wang, Yuan
Guo, Xiaoyan
Zhang, Tianyu
Wang, Xiang
He, Xiangnan
Computer Vision and Pattern Recognition
Reinforcement Learning with Verifiable Rewards (RLVR) and Group Relative Policy Optimization (GRPO) have significantly advanced the reasoning capabilities of large language models. Extending these methods to multimodal settings, however, faces a critical challenge: the instability of std-based normalization, which is easily distorted by extreme samples with nearly positive or negative rewards. Unlike pure-text LLMs, multimodal models are particularly sensitive to such distortions, as both perceptual and reasoning errors influence their responses. To address this, we characterize each sample by its difficulty, defined through perceptual complexity (measured via visual entropy) and reasoning uncertainty (captured by model confidence). Building on this characterization, we propose difficulty-aware group normalization (Durian), which re-groups samples by difficulty levels and shares the std within each group. Our approach preserves GRPO's intra-group distinctions while eliminating sensitivity to extreme cases, yielding significant performance gains across multiple multimodal reasoning benchmarks.
title Enhancing Multi-Modal LLMs Reasoning via Difficulty-Aware Group Normalization
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2602.21743