arXivDaily arXiv每日学术速递 周一至周五更新
​通知:联邦节假日调休:哥伦布日 / 原住民日(Columbus Day / Indigenous Peoples' Day),今日(13日)无更新。
arXiv 2603.03437cs.CV

超越准确率:评估多模态医学推理中的视觉语义

Beyond Accuracy: Evaluating Visual Grounding In Multimodal Medical Reasoning

The University of Texas MD Anderson Cancer Center(德克萨斯大学MD安德森癌症中心);Cohere Labs(Cohere实验室);Eisai Inc.(艾伯维公司);Indian Institute of Science, Bangalore(班加罗尔印度科学研究院)

Anas Zafar, Leema Krishna Murali, Ashish Vashist

AI总结:

该研究提出反事实评估框架,通过测量视觉依赖性得分和幻觉视觉推理率,揭示仅文本强化学习在多模态医学推理中降低视觉依赖性的问题。

摘要:

近期研究表明,仅文本的强化学习结合可验证奖励(RLVR)在多模态医学VQA基准测试中可以匹配或优于图像-文本RLVR,这表明当前的评估协议可能无法衡量因果性的视觉依赖性。我们引入了一个反事实评估框架,利用真实、空白和洗牌的图像在四个医学VQA基准测试中进行评估:PathVQA、PMC-VQA、SLAKE和VQA-RAD。除了准确率之外,我们测量了视觉依赖性得分(VRS)、图像敏感度(IS),并引入了幻觉视觉推理率(HVRR)来检测模型在产生图像不变答案的情况下仍生成视觉主张的情况。我们的发现表明,RLVR在提高准确率的同时会降低视觉依赖性:仅文本的RLVR在PathVQA上实现了负的VRS(-0.09),在不匹配图像的情况下表现更好,而图像-文本的RLVR总体图像敏感度降低至39.8%尽管提高了准确率。在VQA-RAD上,两种变体通过不同的机制实现了63%的准确率:仅文本的RLVR在空白图像中保留了81%的性能,而图像-文本的RLVR仅显示29%的图像敏感度。模型在68-74%的响应中生成视觉主张,但38-43%是未基于视觉的(HVRR)。这些发现表明,仅准确率的奖励能够导致捷径利用,而进步需要基于视觉依赖性的评估协议和训练目标。

英文摘要:

Recent work shows that text-only reinforcement learning with verifiable rewards (RLVR) can match or outperform image-text RLVR on multimodal medical VQA benchmarks, suggesting current evaluation protocols may fail to measure causal visual dependence. We introduce a counterfactual evaluation framework using real, blank, and shuffled images across four medical VQA benchmarks: PathVQA, PMC-VQA, SLAKE, and VQA-RAD. Beyond accuracy, we measure Visual Reliance Score (VRS), Image Sensitivity (IS), and introduce Hallucinated Visual Reasoning Rate (HVRR) to detect cases where models generate visual claims despite producing image-invariant answers. Our findings reveal that RLVR improves accuracy while degrading visual grounding: text-only RLVR achieves negative VRS on PathVQA (-0.09), performing better with mismatched images, while image-text RLVR reduces image sensitivity to 39.8% overall despite improving accuracy. On VQA-RAD, both variants achieve 63% accuracy through different mechanisms: text-only RLVR retains 81% performance with blank images, while image-text RLVR shows only 29% image sensitivity. Models generate visual claims in 68-74% of responses, yet 38-43% are ungrounded (HVRR). These findings demonstrate that accuracy-only rewards enable shortcut exploitation, and progress requires grounding-aware evaluation protocols and training objectives that explicitly enforce visual dependence.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑