Uncertainty-o: One Model-agnostic Framework for Unveiling Uncertainty in Large Multimodal Models

Ruiyang Zhang, Junhao Zhang, Hao Fei, Zhedong Zheng


Abstract
Large Multimodal Models (LMMs), characterized by their humanoid perception and generation capabilities, have been widely applied in critical physical world scenarios, yet their uncertainty remains mostly unknown. In this paper, we aim to answer three substantial questions: (1) Can we explicitly capture the uncertainty of LMMs? (2) How can we tackle the reasoning complexity arising from prompts across various modalities? (3) How can we quantify the uncertainty of LMMs when their responses extend to multiple modalities, beyond mere text? To answer these questions, we propose Uncertainty-o: (1) Uncertainty-o can explicitly estimate uncertainty of LMMs, with prompts and responses across five modalities, namely text, image, audio, video, and point cloud. (2) We propose multimodal prompt perturbation, where empirical studies indicate that semantically equivalent perturbations are more effective for eliciting LMM uncertainty. (3) We introduce multimodal semantic uncertainty, enabling uncertainty estimation when LMMs generate multimodal responses. Extensive quantitative and qualitative analyses validate the efficacy of Uncertainty-o in reliably estimating the uncertainty inherent in LMMs.
Anthology ID:
2026.findings-emnlp.110
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2270–2285
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.110/
DOI:
Bibkey:
Cite (ACL):
Ruiyang Zhang, Junhao Zhang, Hao Fei, and Zhedong Zheng. 2026. Uncertainty-o: One Model-agnostic Framework for Unveiling Uncertainty in Large Multimodal Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 2270–2285, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Uncertainty-o: One Model-agnostic Framework for Unveiling Uncertainty in Large Multimodal Models (Zhang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.110.pdf