Preconditioned Test-Time Adaptation for Out-of-Distribution Debiasing in Narrative Generation

Hanwen Shen, Ting Ying, Jiajie Lu, Shanshan Wang


Abstract
Although debiased large language models (LLMs) excel at handling known or low-bias prompts, they often fail on unfamiliar and high-bias prompts. We demonstrate via out-of-distribution (OOD) detection that these high-bias prompts cause a distribution shift, degrading static model performance. To enable real-time correction, we propose CAP-TTA, a test-time adaptation framework. CAP-TTA triggers context-aware LoRA updates only when a bias-risk score exceeds a set threshold. By utilizing an offline precomputed diagonal preconditioner, it ensures fast and stable optimization. Across multiple benchmarks and human evaluations, CAP-TTA effectively reduces toxicity/bias score with significantly lower latency than standard optimization methods (e.g., AdamW or SGD). Furthermore, it prevents catastrophic forgetting, and substantially improves narrative fluency over state-of-the-art baselines without compromising debiasing performance.
Anthology ID:
2026.acl-long.919
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
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
20071–20104
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.919/
DOI:
Bibkey:
Cite (ACL):
Hanwen Shen, Ting Ying, Jiajie Lu, and Shanshan Wang. 2026. Preconditioned Test-Time Adaptation for Out-of-Distribution Debiasing in Narrative Generation. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 20071–20104, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Preconditioned Test-Time Adaptation for Out-of-Distribution Debiasing in Narrative Generation (Shen et al., ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-long.919.pdf
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