@inproceedings{luo-etal-2026-tia,
title = "{TIA}-{VL}: Diagnosing and Correcting Template-Induced Ambiguity in Medical Vision-Language Decisions",
author = "Luo, Yifan and
Shi, Jiaran and
Wang, Guoming and
Tang, Siliang",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {EMNLP} 2026",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-emnlp.538/",
pages = "11303--11319",
ISBN = "979-8-89176-462-0",
abstract = "Medical vision-language models (VLMs) are often evaluated by report retrieval, grounding, and explanation quality. We show that these metrics can create a metric illusion: a model may appear clinically grounded while exploiting acquisition template, crop, orientation, or protocol rather than patient anatomy. We formalize this failure as template-induced ambiguity and introduce TIA-VL, a counterfactual benchmark with source, template-family, severity, and compound protocol shifts. We also propose Rationale-Grounded Template Ambiguity Calibration (R-GTAC), a plug-in calibration layer that discounts template-dominated evidence while preserving anatomy and textual rationale support. Across strong medical VLM-style baselines, including BioViL-T-style frozen features, adapter features, and anatomy-teacher features, R-GTAC reduces wrong same-template errors to 0.0000 on the main protocol splits. We then test whether systems know when to abstain through readiness and counterfactual rationale deferral. Counterfactual rationale readiness filtering further identifies a reliable low-risk 25{\%} subset reaching 0.8500 Top-1 on the hardest compound shift, while revealing that coupled protocol shifts pose critical frontiers for global risk calibration. Thus, TIA-VL supports a conservative message for medical VLM evaluation: models should be judged not only by whether they answer, but by whether their apparent rationales survive anti-shortcut counterfactuals. The code and benchmark will be available at https://github.com/YifanLuo0103/TIA-VL."
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<abstract>Medical vision-language models (VLMs) are often evaluated by report retrieval, grounding, and explanation quality. We show that these metrics can create a metric illusion: a model may appear clinically grounded while exploiting acquisition template, crop, orientation, or protocol rather than patient anatomy. We formalize this failure as template-induced ambiguity and introduce TIA-VL, a counterfactual benchmark with source, template-family, severity, and compound protocol shifts. We also propose Rationale-Grounded Template Ambiguity Calibration (R-GTAC), a plug-in calibration layer that discounts template-dominated evidence while preserving anatomy and textual rationale support. Across strong medical VLM-style baselines, including BioViL-T-style frozen features, adapter features, and anatomy-teacher features, R-GTAC reduces wrong same-template errors to 0.0000 on the main protocol splits. We then test whether systems know when to abstain through readiness and counterfactual rationale deferral. Counterfactual rationale readiness filtering further identifies a reliable low-risk 25% subset reaching 0.8500 Top-1 on the hardest compound shift, while revealing that coupled protocol shifts pose critical frontiers for global risk calibration. Thus, TIA-VL supports a conservative message for medical VLM evaluation: models should be judged not only by whether they answer, but by whether their apparent rationales survive anti-shortcut counterfactuals. The code and benchmark will be available at https://github.com/YifanLuo0103/TIA-VL.</abstract>
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%0 Conference Proceedings
%T TIA-VL: Diagnosing and Correcting Template-Induced Ambiguity in Medical Vision-Language Decisions
%A Luo, Yifan
%A Shi, Jiaran
%A Wang, Guoming
%A Tang, Siliang
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Findings of the Association for Computational Linguistics: EMNLP 2026
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-462-0
%F luo-etal-2026-tia
%X Medical vision-language models (VLMs) are often evaluated by report retrieval, grounding, and explanation quality. We show that these metrics can create a metric illusion: a model may appear clinically grounded while exploiting acquisition template, crop, orientation, or protocol rather than patient anatomy. We formalize this failure as template-induced ambiguity and introduce TIA-VL, a counterfactual benchmark with source, template-family, severity, and compound protocol shifts. We also propose Rationale-Grounded Template Ambiguity Calibration (R-GTAC), a plug-in calibration layer that discounts template-dominated evidence while preserving anatomy and textual rationale support. Across strong medical VLM-style baselines, including BioViL-T-style frozen features, adapter features, and anatomy-teacher features, R-GTAC reduces wrong same-template errors to 0.0000 on the main protocol splits. We then test whether systems know when to abstain through readiness and counterfactual rationale deferral. Counterfactual rationale readiness filtering further identifies a reliable low-risk 25% subset reaching 0.8500 Top-1 on the hardest compound shift, while revealing that coupled protocol shifts pose critical frontiers for global risk calibration. Thus, TIA-VL supports a conservative message for medical VLM evaluation: models should be judged not only by whether they answer, but by whether their apparent rationales survive anti-shortcut counterfactuals. The code and benchmark will be available at https://github.com/YifanLuo0103/TIA-VL.
%U https://aclanthology.org/2026.findings-emnlp.538/
%P 11303-11319
Markdown (Informal)
[TIA-VL: Diagnosing and Correcting Template-Induced Ambiguity in Medical Vision-Language Decisions](https://aclanthology.org/2026.findings-emnlp.538/) (Luo et al., Findings 2026)
ACL