Benchmarking and Mitigating the Impact of Noisy User Prompts in Medical VLMs via Cross-Modal Reflection

Zhiyu Xue, Reza Abbasi-Asl, Ramtin Pedarsani


Abstract
Medical vision-language models (Med-VLMs) offer a new and effective paradigm for digital health in tasks such as disease diagnosis using clinical images and text. In these tasks, an important but underexplored research question is how Med-VLMs interpret and respond to user-provided clinical information, especially when the prompts are noisy. For a systematic evaluation, we construct Med-CP, a large-scale visual question answering (VQA) benchmark designed to comprehensively evaluate the influence of clinical prompts across diverse modalities, anatomical regions, and diagnostic tasks. Our experiments reveal that existing Med-VLMs tend to follow user-provided prompts blindly, regardless of whether they are accurate or not, raising concerns about their reliability in real-world interactions. To address this problem, we introduce a novel supervised fine-tuning (SFT) approach for Med-VLMs based on cross-modal reflection chain-of-thought (CoT) across medical images and text. In our SFT method, the Med-VLM is trained to produce reasoning paths for the analysis of the medical image and the user-provided prompt. Then, the final answer is determined by conducting a reflection on the visual and textual information. Experimental results demonstrate that our method considerably enhances the robustness against noisy user-provided prompts for both in-domain and out-of-domain evaluation scenarios.
Anthology ID:
2026.eacl-industry.67
Volume:
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 5: Industry Track)
Month:
March
Year:
2026
Address:
Rabat, Morocco
Editors:
Yevgen Matusevych, Gülşen Eryiğit, Nikolaos Aletras
Venue:
EACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
900–914
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.eacl-industry.67/
DOI:
Bibkey:
Cite (ACL):
Zhiyu Xue, Reza Abbasi-Asl, and Ramtin Pedarsani. 2026. Benchmarking and Mitigating the Impact of Noisy User Prompts in Medical VLMs via Cross-Modal Reflection. In Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 5: Industry Track), pages 900–914, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
Benchmarking and Mitigating the Impact of Noisy User Prompts in Medical VLMs via Cross-Modal Reflection (Xue et al., EACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-eacl/2026.eacl-industry.67.pdf