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New Evidence, Same Choice: Testing Physical Experiment Selection in Vision Language Models

arxiv.org/abs/2609.11022

Updated 20 min ago · first seen 11 Sept 2026

paper_01M294FQFK00MFZKWWZTYGTYXX

Published
11 Sept 2026
T1 · 21 min ago
arXiv
2609.11022
T1 · 21 min ago
Category
cs.CV
T1 · 21 min ago

Abstract

A model first sees an image from one physical measurement experiment, such as how far a block coasted, and must answer a question about a new trial, such as whether the block will pass a target after a fixed push. The initial experiment may provide enough information to answer, or the model may need another measurement, such as the object's mass, friction, restitution, or spring stiffness. We study whether vision language models can decide when to answer immediately and, when more evidence is needed, which experiment to perform. Current physical reasoning benchmarks usually evaluate only the final answer, so they do not directly measure this decision-making ability. We introduce a controlled evaluation where each problem provides one measurement image and four possible physical worlds created by combining two possible masses and two possible values of another relevant property. The model must either stop and answer or select the cheapest additional experiment that can resolve the question. We construct matched problem pairs where changing either the observed measurement or the question changes the optimal action. Since all possible worlds and experiment costs are known, we can explicitly determine the optimal choice. Across six open models and 144 physical parameter sets, direct responses repeat the same action for 95.1% to 100% of image pairs even when the correct action changes. Brief reasoning improves action switching, but the best model makes both decisions correctly for only 5.9% of image pairs. Additional analysis reveals failures in measurement interpretation, physical reasoning, and response formatting. By evaluating evidence selection separately from final answers, our benchmark reveals limitations in physical reasoning that conventional answer accuracy can overlook.

Authors 7

Sourajit Saha, Shubhashis Roy Dipta, Nobin Sarwar, Shaswati Saha, Yuxuan Jiang, Siyuan Li, Qiheng Wang

Specification

Official page

Source:arXiv (Atom API + RSS)T1observed 21 min agohigh

Arxiv announce type
new

Source:arXiv (Atom API + RSS)T1observed 20 min agohigh

arXiv id
2609.11022

Source:arXiv (Atom API + RSS)T1observed 21 min agohigh

Categories
cs.CV, cs.AI, cs.CL, cs.LG

Source:arXiv (Atom API + RSS)T1observed 21 min agohigh

PDF

Source:arXiv (Atom API + RSS)T1observed 21 min agohigh

Primary category
cs.CV

Source:arXiv (Atom API + RSS)T1observed 21 min agohigh

Published
11 Sept 2026

Source:arXiv (Atom API + RSS)T1observed 21 min agohigh

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Provenance

Attributed facts

9

Source tiers

T19

Freshest observation

20 min ago

Conflicts

None