DUD: Decoupled Update Dynamics for Reliable Uncertainty Quantification in Large Language Models

Yixin Bu, Runze Xia, Guanyun Zou, Yupeng Ji, Hongliang Dai, Haodong Liu, Piji Li


Abstract
Accurate Uncertainty Quantification (UQ) is critical for reliable deployment of Large Language Models (LLMs), yet traditional probability-based metrics often fail to capture the model’s true epistemic state. While recent mechanistic approaches leverage hidden state dynamics, they typically aggregate residual stream updates, conflating the distinct roles of parametric memory (Feed-Forward Networks) and contextual processing (Attention). We argue that this aggregation obscures fine-grained mechanistic conflicts, such as memory-context misalignment, that are fundamental indicators of uncertainty. To address this, we introduce **D**ecoupled **U**pdate **D**ynamics (**DUD**), a framework that explicitly decouples FFN and Attention contributions via noise-induced causal interventions. By quantifying the independent restoration capabilities of each module, we construct a dual-stream dynamic profile that captures the model’s internal fragility. Extensive experiments demonstrate that DUD significantly outperforms state-of-the-art baselines in both uncertainty estimation and calibration, while exhibiting superior cross-dataset generalization, validating decoupled dynamics as a robust proxy for model faithfulness.
Anthology ID:
2026.acl-long.1665
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
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Publisher:
Association for Computational Linguistics
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Pages:
35972–35993
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URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.1665/
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Cite (ACL):
Yixin Bu, Runze Xia, Guanyun Zou, Yupeng Ji, Hongliang Dai, Haodong Liu, and Piji Li. 2026. DUD: Decoupled Update Dynamics for Reliable Uncertainty Quantification in Large Language Models. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 35972–35993, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
DUD: Decoupled Update Dynamics for Reliable Uncertainty Quantification in Large Language Models (Bu et al., ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-long.1665.pdf
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