Analyzing and Mitigating Cross-Lingual Degradation in Multilingual Medical VQA

Jingbo Wang, Sendong Zhao, Haochun Wang, Bing Qin, Ting Liu


Abstract
Medical visual question answering (VQA) is a crucial task in clinical AI, yet its evaluation has so far centered almost exclusively on English, limiting its relevance to linguistically diverse patients and clinicians. Recent multilingual medical VQA benchmarks show that large vision-language models (LVLMs) degrade in non-English languages, but lack a fine-grained analysis of how cross-lingual variation affects the distinct capabilities that medical VQA requires. To this end, we construct a multilingual medical VQA benchmark over eight languages, organized into four representative scenarios that isolate the core capabilities medical VQA requires. Evaluating five open- and closed-source LVLMs, we find that cross-lingual degradation is not uniform but highly scenario-dependent. We therefore propose MedVL-XLRepE, a training-free scenario-aware representation engineering method, leveraging LVLMs’ superior English medical VQA capability to steer non-English representations toward their English counterparts at inference time. Across three LVLMs and eight languages, MedVL-XLRepE consistently mitigates cross-lingual degradation, with gains of up to 6.33%.
Anthology ID:
2026.emnlp-main.920
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
21191–21208
Language:
URL:
https://aclanthology.org/2026.emnlp-main.920/
DOI:
Bibkey:
Cite (ACL):
Jingbo Wang, Sendong Zhao, Haochun Wang, Bing Qin, and Ting Liu. 2026. Analyzing and Mitigating Cross-Lingual Degradation in Multilingual Medical VQA. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 21191–21208, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Analyzing and Mitigating Cross-Lingual Degradation in Multilingual Medical VQA (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.920.pdf