Investigating The Functional Roles of Attention Heads in Vision Language Models: Evidence for Reasoning Modules

Fuente: arXiv
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Auteurs principaux: Jiang, Yanbei, Ma, Xueqi, Liu, Shu, Erfani, Sarah Monazam, Liu, Tongliang, Bailey, James, Lau, Jey Han, Ehinger, Krista A.
Format: Preprint
Publié: 2025
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author Jiang, Yanbei
Ma, Xueqi
Liu, Shu
Erfani, Sarah Monazam
Liu, Tongliang
Bailey, James
Lau, Jey Han
Ehinger, Krista A.
author_facet Jiang, Yanbei
Ma, Xueqi
Liu, Shu
Erfani, Sarah Monazam
Liu, Tongliang
Bailey, James
Lau, Jey Han
Ehinger, Krista A.
contents Despite excelling on multimodal benchmarks, vision-language models (VLMs) largely remain a black box. In this paper, we propose a novel interpretability framework to systematically analyze the internal mechanisms of VLMs, focusing on the functional roles of attention heads in multimodal reasoning. To this end, we introduce CogVision, a dataset that decomposes complex multimodal questions into step-by-step subquestions designed to simulate human reasoning through a chain-of-thought paradigm, with each subquestion associated with specific receptive or cognitive functions such as high-level visual reception and inference. Using a probing-based methodology, we identify attention heads that specialize in these functions and characterize them as functional heads. Our analysis across diverse VLM families reveals that these functional heads are universally sparse, vary in number and distribution across functions, and mediate interactions and hierarchical organization. Furthermore, intervention experiments demonstrate their critical role in multimodal reasoning: removing functional heads leads to performance degradation, while emphasizing them enhances accuracy. These findings provide new insights into the cognitive organization of VLMs and suggest promising directions for designing models with more human-aligned perceptual and reasoning abilities.
format Preprint
id arxiv_https___arxiv_org_abs_2512_10300
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Investigating The Functional Roles of Attention Heads in Vision Language Models: Evidence for Reasoning Modules
Jiang, Yanbei
Ma, Xueqi
Liu, Shu
Erfani, Sarah Monazam
Liu, Tongliang
Bailey, James
Lau, Jey Han
Ehinger, Krista A.
Artificial Intelligence
Despite excelling on multimodal benchmarks, vision-language models (VLMs) largely remain a black box. In this paper, we propose a novel interpretability framework to systematically analyze the internal mechanisms of VLMs, focusing on the functional roles of attention heads in multimodal reasoning. To this end, we introduce CogVision, a dataset that decomposes complex multimodal questions into step-by-step subquestions designed to simulate human reasoning through a chain-of-thought paradigm, with each subquestion associated with specific receptive or cognitive functions such as high-level visual reception and inference. Using a probing-based methodology, we identify attention heads that specialize in these functions and characterize them as functional heads. Our analysis across diverse VLM families reveals that these functional heads are universally sparse, vary in number and distribution across functions, and mediate interactions and hierarchical organization. Furthermore, intervention experiments demonstrate their critical role in multimodal reasoning: removing functional heads leads to performance degradation, while emphasizing them enhances accuracy. These findings provide new insights into the cognitive organization of VLMs and suggest promising directions for designing models with more human-aligned perceptual and reasoning abilities.
title Investigating The Functional Roles of Attention Heads in Vision Language Models: Evidence for Reasoning Modules
topic Artificial Intelligence
url https://arxiv.org/abs/2512.10300