Beyond Modality Collapse: Taming Guided Modality Entropy for Omni-modal Emotion Reasoning

摘要

Omni-modal Large Language Models (OLLMs) excel in diverse tasks but struggle with complex emotional reasoning, which requires integrating textual, visual, and acoustic signals. We attribute this limitation to modality collapse, where models over-rely on a dominant modality while neglecting complementary cues. To address this issue, we introduce OmniCoT, a data paradigm that interleaves guided tokens (e.g., [vision], [audio]) into reasoning traces to enforce structured evidence extraction. To further internalize the reasoning behaviors instilled by OmniCoT and facilitate adaptive modality prioritization, we propose Dynamic Modality-Entropy GRPO (DyME-GRPO), which utilizes entropy-based uncertainty estimates over Guided Tokens (GTs) to regulate modality usage, thereby mitigating collapse and informational redundancy. By applying supervised fine-tuning with OmniCoT followed by DyME-GRPO, we develop EmoOmni based on the Qwen2.5-Omni-7B backbone. Extensive experiments demonstrate that EmoOmni achieves state-of-the-art performance on multiple emotion recognition and reasoning benchmarks while preserving the general capabilities of the base model. These findings highlight the potential of our work for omni-modal reasoning across a broader range of complex tasks.