Team champ at SHROOM-Visions: Transferring Fine-Grained Hallucination Detection with Hidden-State Probes and Backbone Adaptation

Aygalic Jara–Mikolajczak, Thomas Lavergne, Sophie Rosset


Abstract
We describe a multilingual, character-level hallucination detection system for vision-language models combining multi-layer hidden states, text-to-vision LoRA transfer, multitask learning, and language-specific span emission. Our submission achieved a validation Character AUPRC of 0.5530 and an average test Cor/Cor+lbl of 0.5243/0.4174. A controlled post-submission factorial analysis improved validation Character AUPRC to 0.5595. Team champ placed third in French, fourth in Italian and Chinese, and fifth in English.
Anthology ID:
2026.uncertainlp-main.62
Volume:
The Proceedings of the Third Workshop on Uncertainty-Aware NLP
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Wilker Aziz, Jonathan Berant, Bryan Eikema, Evgenia Ilia, Marie-Catherine de Marneffe, Barbara Plank, Artem Shelmanov, Swabha Swayamdipta, Jörg Tiedemann, Artem Vazhentsev, Raúl Vázquez, Chrysoula Zerva
Venues:
UncertaiNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
856–862
Language:
URL:
https://aclanthology.org/2026.uncertainlp-main.62/
DOI:
Bibkey:
Cite (ACL):
Aygalic Jara–Mikolajczak, Thomas Lavergne, and Sophie Rosset. 2026. Team champ at SHROOM-Visions: Transferring Fine-Grained Hallucination Detection with Hidden-State Probes and Backbone Adaptation. In The Proceedings of the Third Workshop on Uncertainty-Aware NLP, pages 856–862, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Team champ at SHROOM-Visions: Transferring Fine-Grained Hallucination Detection with Hidden-State Probes and Backbone Adaptation (Jara–Mikolajczak et al., UncertaiNLP 2026)
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PDF:
https://aclanthology.org/2026.uncertainlp-main.62.pdf