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PDCR: Perception-Decomposed Confidence Reward for Vision-Language Reasoning
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Proposes PDCR, which splits V-L reasoning steps into visual-perception and textual-reasoning clusters via a white-image Visual Dependence Score and Otsu thresholding, then normalizes confidence-gain advantages within each cluster, improving GRPO/PACR on Qwen2.5-VL.
Problem
Naively applying a globally normalized ground-truth confidence-growth process reward to vision-language reasoning distorts the signal for sparse visual perception steps, since the global statistics are dominated by dense textual reasoning steps.
Approach
Decompose reasoning steps without external labels using a Visual Dependence Score (log-likelihood ratio of a step under the real image vs. a white image), cluster steps with Otsu's method, and compute min-max normalized confidence-gain advantages separately within each cluster.
Key results
- On Qwen2.5-VL-7B, PDCR averages 52.9 across seven benchmarks vs. 52.2 for PACR, 52.0 for DAPO and 51.5 for GRPO.
- On Qwen2.5-VL-3B, PDCR averages 45.2 vs. 44.4 for PACR and 43.6 for GRPO.
- Random decomposition on 7B drops average to 52.3, showing the gain depends on the Visual Dependence Score clustering; Otsu clustering reaches 76.2% agreement with GPT-5 labels vs. 67.5% for best Top-K.
Surprising findings
- Rotating the image by 90 degrees gives poor skill separation (65.9%), suggesting VLMs are fairly rotation-invariant for this signal.
- Random decomposition with the same decomposed advantage barely improves over PACR, so the gain depends on correct clustering.
Limitations
- Higher training compute per step than GRPO due to extra forward passes for confidence gains and visual dependence scores.
- Binary hard clustering may misassign hybrid perception-reasoning steps.
- Skill labels for validation were produced by GPT-5 and checked on only 100 steps by humans.
Experimental setup
Datasets: Vision-SR1-47K GPT-5-annotated skill labels on 10,000 Qwen2.5-VL-7B trajectories
Benchmarks: MMMU-Pro MMMU RealWorldQA VisNumBench MathVerse MathVision HallusionBench
Metrics: accuracy average accuracy skill classification accuracy Cohen's kappa
Baselines: GRPO DAPO PACR Visionary-R1 Perception-R1 Vision-R1 Random Decomposition
Builds on: GRPO PACR DAPO Otsu's method EasyR1
Closest papers by meaning
- Improving Vision-language Models with Perception-centric Process Reward Models (CVPR 2026 · similarity 0.92)
- Bad Seeing or Bad Thinking? Rewarding Perception for Multimodal Reasoning (ICML 2026 · similarity 0.92)
- Perception-R1: Advancing Multimodal Reasoning Capabilities of MLLMs via Visual Perception Reward (ICLR 2026 · similarity 0.91)
- SSL4RL: Revisiting Self-supervised Learning as Intrinsic Reward for Visual-Language Reasoning (ICML 2026 · similarity 0.90)
- Perceptual-Evidence Anchored Reinforced Learning for Multimodal Reasoning (CVPR 2026 · similarity 0.90)
- Perception-Aware Policy Optimization for Multimodal Reasoning (ICLR 2026 · similarity 0.90)
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