Readout is not Recovery: Dissociating Coordinate Emission from Visual-Corruption Repair in Vision-Language Models
On the map: Multimodal LLMs / vision-language models → Visual token pruning and efficiency
Abstract (arXiv)
VLM bounding-box localization is both language generation and spatial commitment. Parseable fields such as bbox2d make localization easy to score, but dimensions that emit coordinate tokens need not repair localization after visual evidence is damaged. We study this readout/recovery separation in Qwen3-VL-4B-Instruct on single-object COCO grounding. We compare clean coordinate-token readout rankings with corruption-derived repair rankings, using object-mask endpoint replacement for recovery and clean-input flooring for depth localization. In Qwen3-VL, coordinate-token rankings are inert through layer 24, load-bearing from layers 32-35, and peak at layer 34; corruption-derived rankings harm layers 16-24 but become beneficial near layer 35/final. A Kimi-VL-A3B diagnostic shows a matching output-proximal transition despite a different box format. Object-mask recovery separates rank budgets: k=250 shows necessity, k=500 shows Top-k restoration above random, and k=d/2 is largely capacity-driven. Partial-occlusion sweeps reveal that high-overlap coordinate-token sets can hurt at k=1000 and help mainly at half-width, while population corruption-derived sets provide no reliable fixed repair set. Edge-attribution patching shows coordinate-token paths are high precision but low recall for detection recovery, and RMSNorm quasi-layer controls do not close the endpoint-repair gap. Endpoint coordinate triage is therefore a useful circuit prior, but occlusion recovery requires a separate benchmark.
Key facts. No citing papers in the map yet (data through 14 Oct 2026). Placed in Visual token pruning and efficiency, one of 16 directions in Multimodal LLMs / vision-language models. Builds on 18 of its 21 references that are in the map. First posted on arXiv 26 Sep 2026.
Builds on
18 of 21 references.
References · 18
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6 more
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- 2025Mitigating Coordinate Prediction Bias from Positional Encoding Failures
- 2025Pathological Truth Bias in Vision-Language Models
- 2026Edge Reliability Gap in Vision-Language Models: Quantifying Failure Modes of Compressed VLMs Under Visual Corruption
- 2026Reroute, Don't Remove: Recoverable Visual Token Routing for Vision-Language Models
- 2025Grounding-Aware Token Pruning: Recovering from Drastic Performance Drops in Visual Grounding Caused by Pruning
- 2026From Patching to Pruning Visual Computation in Vision Language Models