A Unified Ambiguity Signal for Calibrated Multimodal Emotion Recognition

Tahir Ahmad, Raza Mukhtar, Chanjun Park, Yeo Chan Yoon


Abstract
Multimodal emotion recognition (MER) in conversation is inherently ambiguous, as linguistic, acoustic, and visual cues may support multiple plausible interpretations. Existing approaches often treat ambiguity as prediction uncertainty rather than modeling its structured sources. We propose UAF, an ambiguity-aware framework for MER built around a single unified ambiguity signal. UAF estimates a normalized per-sample Model-based Ambiguity Degree (MAD) from the predicted emotion distribution by measuring its proximity to the maximally ambiguous uniform distribution, and uses it as a shared control signal rather than a post-hoc uncertainty score. This single scalar coordinates three parts of learning: it aligns representation radius with ambiguity, emphasizes ambiguous samples during optimization, and scales OT-based perturbation consistency. The fused evidence is organized into context, speaker, temporal, cross-modal, and residual subspaces that serve as the substrate on which this signal operates. Experiments on IEMOCAP, CMU-MOSEI, and MELD show that UAF yields consistently better calibration and high-ambiguity reliability alongside competitive accuracy and weighted-F1, showing that a single ambiguity signal can be an effective shared training signal for reliable MER
Anthology ID:
2026.aacl-long.111
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2432–2453
Language:
URL:
https://aclanthology.org/2026.aacl-long.111/
DOI:
Bibkey:
Cite (ACL):
Tahir Ahmad, Raza Mukhtar, Chanjun Park, and Yeo Chan Yoon. 2026. A Unified Ambiguity Signal for Calibrated Multimodal Emotion Recognition. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 2432–2453, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
A Unified Ambiguity Signal for Calibrated Multimodal Emotion Recognition (Ahmad et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.111.pdf