Responses Fall Short of Understanding: Revealing the Gap between Internal Representations and Responses in Visual Document Understanding

Fuente: arXiv
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Autori principali: Kawasaki, Haruka, Tanaka, Ryota, Nishida, Kyosuke
Natura: Preprint
Pubblicazione: 2026
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author Kawasaki, Haruka
Tanaka, Ryota
Nishida, Kyosuke
author_facet Kawasaki, Haruka
Tanaka, Ryota
Nishida, Kyosuke
contents Visual document understanding (VDU) is a challenging task for large vision language models (LVLMs), requiring the integration of visual perception, text recognition, and reasoning over structured layouts. Although recent LVLMs have shown progress on VDU benchmarks, their performance is typically evaluated based on generated responses, which may not necessarily reflect whether the model has actually captured the required information internally. In this paper, we investigate how information required to solve VDU tasks is represented across different layers of LLMs within LVLMs using linear probing. Our study reveals that (1) there is a clear gap between internal representations and generated responses, and (2) information required to solve the task is often encoded more linearly from intermediate layers than from the final layer. Motivated by these findings, we explore fine-tuning strategies that target intermediate layers. Experiments show that fine-tuning intermediate layers improves both linear probing accuracy and response accuracy while narrowing the gap.
format Preprint
id arxiv_https___arxiv_org_abs_2604_04411
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Responses Fall Short of Understanding: Revealing the Gap between Internal Representations and Responses in Visual Document Understanding
Kawasaki, Haruka
Tanaka, Ryota
Nishida, Kyosuke
Computation and Language
Artificial Intelligence
Computer Vision and Pattern Recognition
Visual document understanding (VDU) is a challenging task for large vision language models (LVLMs), requiring the integration of visual perception, text recognition, and reasoning over structured layouts. Although recent LVLMs have shown progress on VDU benchmarks, their performance is typically evaluated based on generated responses, which may not necessarily reflect whether the model has actually captured the required information internally. In this paper, we investigate how information required to solve VDU tasks is represented across different layers of LLMs within LVLMs using linear probing. Our study reveals that (1) there is a clear gap between internal representations and generated responses, and (2) information required to solve the task is often encoded more linearly from intermediate layers than from the final layer. Motivated by these findings, we explore fine-tuning strategies that target intermediate layers. Experiments show that fine-tuning intermediate layers improves both linear probing accuracy and response accuracy while narrowing the gap.
title Responses Fall Short of Understanding: Revealing the Gap between Internal Representations and Responses in Visual Document Understanding
topic Computation and Language
Artificial Intelligence
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2604.04411