Poly-FEVER: A Multilingual Hallucination Detection Benchmark

Hanzhi Zhang, Sumera Anjum, Heng Fan, Weijian Zheng, Yan Huang, Yunhe Feng


Abstract
We present Poly-FEVER, an open-source large-scale multilingual benchmark for hallucination detection through controlled factuality judgment in large language models. Poly-FEVER extends FEVER, Climate-FEVER, and SciFact to 77,973 Supported/Refuted claims aligned across 11 languages. We augment each claim with topic metadata from a 22-topic LDA model, enabling topic-aware analysis of multilingual factuality behavior. Translations are produced with Google Cloud Translation and validated by a targeted human audit, GEMBA, and COMETKiwi. We benchmark ChatGPT-3.5, LLaMA-2/3, Phi-3.5, and Mistral across three prompt families and evaluate robustness to model-generated rephrasing. We further analyze resource imbalance using web presence as a proxy for online claim availability, and evaluate retrieval-augmented factuality judgment with DPR over Wikipedia. Results show pronounced cross-lingual disparities under aligned claims, with stronger accuracy in high-resource languages such as English and Chinese and weaker accuracy in lower-resource languages such as Amharic and Tamil. Topic-aware prompting and retrieval provide selective gains, especially in Arabic and Amharic, while their effects vary across languages and can conflict with model priors. Poly-FEVER establishes a rigorous resource for responsible, language-adaptive hallucination detection and language-sensitive factuality evaluation. The proposed Poly-FEVER is available at: https://huggingface.co/datasets/HanzhiZhang/Poly-FEVER.
Anthology ID:
2026.findings-emnlp.540
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:
11353–11369
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.540/
DOI:
Bibkey:
Cite (ACL):
Hanzhi Zhang, Sumera Anjum, Heng Fan, Weijian Zheng, Yan Huang, and Yunhe Feng. 2026. Poly-FEVER: A Multilingual Hallucination Detection Benchmark. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 11353–11369, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Poly-FEVER: A Multilingual Hallucination Detection Benchmark (Zhang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.540.pdf