Light-Weight Hallucination Detection using Contrastive Learning for Conditional Text Generation

Miyu Yamada, Yuki Arase


Abstract
We propose a simple and light-weight, yet effective hallucination detection method for conditional text generation. Hallucinated outputs include information that is either absent from and/or difficult to infer from the input context. Leveraging this feature, we add contrastive learning to the hallucination detection classifier to pull faithful outputs and input contexts together while pushing hallucinated outputs apart. Experimental results confirm that our method on top of RoBERTa improves binary hallucination detection performance, outperforming much larger GPT-4o prompting. Remarkably, our method shows higher performance for outputs where hallucinated spans are sparse.
Anthology ID:
2025.acl-srw.44
Volume:
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 4: Student Research Workshop)
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Jin Zhao, Mingyang Wang, Zhu Liu
Venues:
ACL | WS
SIG:
Publisher:
Association for Computational Linguistics
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Pages:
687–694
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URL:
https://preview.aclanthology.org/landing_page/2025.acl-srw.44/
DOI:
Bibkey:
Cite (ACL):
Miyu Yamada and Yuki Arase. 2025. Light-Weight Hallucination Detection using Contrastive Learning for Conditional Text Generation. In Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 4: Student Research Workshop), pages 687–694, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
Light-Weight Hallucination Detection using Contrastive Learning for Conditional Text Generation (Yamada & Arase, ACL 2025)
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PDF:
https://preview.aclanthology.org/landing_page/2025.acl-srw.44.pdf