System-Mediated Attention Imbalances Make Vision-Language Models Say Yes

Fuente: arXiv
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Auteurs principaux: Chan, Tsan Tsai, Suresh, Varsha, Saha, Anisha, Hahn, Michael, Demberg, Vera
Format: Preprint
Publié: 2026
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author Chan, Tsan Tsai
Suresh, Varsha
Saha, Anisha
Hahn, Michael
Demberg, Vera
author_facet Chan, Tsan Tsai
Suresh, Varsha
Saha, Anisha
Hahn, Michael
Demberg, Vera
contents Vision-language model (VLM) hallucination is commonly linked to imbalanced allocation of attention across input modalities: system, image and text. However, existing mitigation strategies tend towards an image-centric interpretation of these imbalances, often prioritising increased image attention while giving less consideration to the roles of the other modalities. In this study, we evaluate a more holistic, system-mediated account, which attributes these imbalances to functionally redundant system weights that reduce attention to image and textual inputs. We show that this framework offers a useful empirical perspective on the yes-bias, a common form of hallucination in which VLMs indiscriminately respond `yes'. Causally redistributing attention from the system modality to image and textual inputs substantially suppresses this bias, often outperforming existing approaches. We further present evidence suggesting that system-mediated attention imbalances contribute to the yes-bias by encouraging a default reliance on coarse input representations, which are effective for some tasks but ill-suited to others. Taken together, these findings firmly establish system attention as a key factor in VLM hallucination and highlight its potential as a lever for mitigation.
format Preprint
id arxiv_https___arxiv_org_abs_2601_12430
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle System-Mediated Attention Imbalances Make Vision-Language Models Say Yes
Chan, Tsan Tsai
Suresh, Varsha
Saha, Anisha
Hahn, Michael
Demberg, Vera
Computation and Language
I.2.7
Vision-language model (VLM) hallucination is commonly linked to imbalanced allocation of attention across input modalities: system, image and text. However, existing mitigation strategies tend towards an image-centric interpretation of these imbalances, often prioritising increased image attention while giving less consideration to the roles of the other modalities. In this study, we evaluate a more holistic, system-mediated account, which attributes these imbalances to functionally redundant system weights that reduce attention to image and textual inputs. We show that this framework offers a useful empirical perspective on the yes-bias, a common form of hallucination in which VLMs indiscriminately respond `yes'. Causally redistributing attention from the system modality to image and textual inputs substantially suppresses this bias, often outperforming existing approaches. We further present evidence suggesting that system-mediated attention imbalances contribute to the yes-bias by encouraging a default reliance on coarse input representations, which are effective for some tasks but ill-suited to others. Taken together, these findings firmly establish system attention as a key factor in VLM hallucination and highlight its potential as a lever for mitigation.
title System-Mediated Attention Imbalances Make Vision-Language Models Say Yes
topic Computation and Language
I.2.7
url https://arxiv.org/abs/2601.12430