Better Eyes, Better Thoughts: Why Vision Chain-of-Thought Fails in Medicine

Fuente: arXiv
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Autores principales: Wu, Yuan, Yang, Zongxian, Qian, Jiayu, Gao, Songpan, Chen, Guanxing, Li, Qiankun, Huang, Yu-An, Huang, Zhi-An
Formato: Preprint
Publicado: 2026
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author Wu, Yuan
Yang, Zongxian
Qian, Jiayu
Gao, Songpan
Chen, Guanxing
Li, Qiankun
Huang, Yu-An
Huang, Zhi-An
author_facet Wu, Yuan
Yang, Zongxian
Qian, Jiayu
Gao, Songpan
Chen, Guanxing
Li, Qiankun
Huang, Yu-An
Huang, Zhi-An
contents Large vision-language models (VLMs) often benefit from chain-of-thought (CoT) prompting in general domains, yet its efficacy in medical vision-language tasks remains underexplored. We report a counter-intuitive trend: on medical visual question answering, CoT frequently underperforms direct answering (DirA) across general-purpose and medical-specific models. We attribute this to a \emph{medical perception bottleneck}: subtle, domain-specific cues can weaken visual grounding, and CoT may compound early perceptual uncertainty rather than correct it. To probe this hypothesis, we introduce two training-free, inference-time grounding interventions: (i) \emph{perception anchoring} via region-of-interest cues and (ii) \emph{description grounding} via high-quality textual guidance. Across multiple benchmarks and model families, these interventions improve accuracy, mitigate CoT degradation, and in several settings reverse the CoT--DirA inversion. Our findings suggest that reliable clinical VLMs require robust visual grounding and cross-modal alignment, beyond extending text-driven reasoning chains. Code is available \href{https://github.com/TianYin123/Better_Eyes_Better_Thoughts}{here}.
format Preprint
id arxiv_https___arxiv_org_abs_2603_06665
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Better Eyes, Better Thoughts: Why Vision Chain-of-Thought Fails in Medicine
Wu, Yuan
Yang, Zongxian
Qian, Jiayu
Gao, Songpan
Chen, Guanxing
Li, Qiankun
Huang, Yu-An
Huang, Zhi-An
Computer Vision and Pattern Recognition
Artificial Intelligence
Large vision-language models (VLMs) often benefit from chain-of-thought (CoT) prompting in general domains, yet its efficacy in medical vision-language tasks remains underexplored. We report a counter-intuitive trend: on medical visual question answering, CoT frequently underperforms direct answering (DirA) across general-purpose and medical-specific models. We attribute this to a \emph{medical perception bottleneck}: subtle, domain-specific cues can weaken visual grounding, and CoT may compound early perceptual uncertainty rather than correct it. To probe this hypothesis, we introduce two training-free, inference-time grounding interventions: (i) \emph{perception anchoring} via region-of-interest cues and (ii) \emph{description grounding} via high-quality textual guidance. Across multiple benchmarks and model families, these interventions improve accuracy, mitigate CoT degradation, and in several settings reverse the CoT--DirA inversion. Our findings suggest that reliable clinical VLMs require robust visual grounding and cross-modal alignment, beyond extending text-driven reasoning chains. Code is available \href{https://github.com/TianYin123/Better_Eyes_Better_Thoughts}{here}.
title Better Eyes, Better Thoughts: Why Vision Chain-of-Thought Fails in Medicine
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2603.06665