BedBench: humans hit 93.3% on 3D color counting, best VLM just 7.2%

StanfordUniversity · hf · 2026-11-03

A multi-institution paper (Stanford, Toronto, Oxford, etc.) introduces BedBench, a controlled benchmark of thirteen procedurally generated tasks probing both individual judgments and composite answers about 3D object properties. Key findings: exact per-color counting is a glaring weakness — humans score 93.3% vs 7.2% for the best model across twelve open-weight and four frontier models. Fine-tuning raises one model's accuracy from 3.0% to 68.6%, yet its answers about the most common colors stay inconsistent with its own per-color counts; supplying those counts as text improves judgments, showing recovery of a property doesn't mean consistent use. Probing Qwen3.5-27B shows exact counts remain recoverable at the LM input (65.0%) but rarely surface in answers (3.0%). Reasoning, scaling, and visual cues each help individual judgments, none make exact answers reliable; image-removal controls reveal some apparent successes need no visual evidence.

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