I Spy With My Model's Eye: Visual Search as a Behavioural Test for MLLMs

Fuente: arXiv
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Main Authors: Burden, John, Prunty, Jonathan, Slater, Ben, Tehenan, Matthieu, Davis, Greg, Cheke, Lucy
Format: Preprint
Published: 2025
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author Burden, John
Prunty, Jonathan
Slater, Ben
Tehenan, Matthieu
Davis, Greg
Cheke, Lucy
author_facet Burden, John
Prunty, Jonathan
Slater, Ben
Tehenan, Matthieu
Davis, Greg
Cheke, Lucy
contents Multimodal large language models (MLLMs) achieve strong performance on vision-language tasks, yet their visual processing is opaque. Most black-box evaluations measure task accuracy, but reveal little about underlying mechanisms. Drawing on cognitive psychology, we adapt classic visual search paradigms -- originally developed to study human perception -- to test whether MLLMs exhibit the ``pop-out'' effect, where salient visual features are detected independently of distractor set size. Using controlled experiments targeting colour, size and lighting features, we find that advanced MLLMs exhibit human-like pop-out effects in colour or size-based disjunctive (single feature) search, as well as capacity limits for conjunctive (multiple feature) search. We also find evidence to suggest that MLLMs, like humans, incorporate natural scene priors such as lighting direction into object representations. We reinforce our findings using targeted fine-tuning and mechanistic interpretability analyses. Our work shows how visual search can serve as a cognitively grounded diagnostic tool for evaluating perceptual capabilities in MLLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19678
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle I Spy With My Model's Eye: Visual Search as a Behavioural Test for MLLMs
Burden, John
Prunty, Jonathan
Slater, Ben
Tehenan, Matthieu
Davis, Greg
Cheke, Lucy
Computer Vision and Pattern Recognition
Artificial Intelligence
Multimodal large language models (MLLMs) achieve strong performance on vision-language tasks, yet their visual processing is opaque. Most black-box evaluations measure task accuracy, but reveal little about underlying mechanisms. Drawing on cognitive psychology, we adapt classic visual search paradigms -- originally developed to study human perception -- to test whether MLLMs exhibit the ``pop-out'' effect, where salient visual features are detected independently of distractor set size. Using controlled experiments targeting colour, size and lighting features, we find that advanced MLLMs exhibit human-like pop-out effects in colour or size-based disjunctive (single feature) search, as well as capacity limits for conjunctive (multiple feature) search. We also find evidence to suggest that MLLMs, like humans, incorporate natural scene priors such as lighting direction into object representations. We reinforce our findings using targeted fine-tuning and mechanistic interpretability analyses. Our work shows how visual search can serve as a cognitively grounded diagnostic tool for evaluating perceptual capabilities in MLLMs.
title I Spy With My Model's Eye: Visual Search as a Behavioural Test for MLLMs
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2510.19678