MLLM-Microscope: Unlocking Hidden Structure Within Multimodal Large Language Models

Fuente: arXiv
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Main Authors: Mussabayev, Ravil, Mussabayev, Rustam
Format: Preprint
Published: 2026
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author Mussabayev, Ravil
Mussabayev, Rustam
author_facet Mussabayev, Ravil
Mussabayev, Rustam
contents This work presents MLLM-Microscope, a novel system designed for analyzing the hidden representations within Multimodal Large Language Models (MLLMs). Our system evaluates the linearity, intrinsic dimension, and anisotropy of multimodal token embeddings across transformer layers. Utilizing the ScienceQA dataset, we evaluate two state-of-the-art MLLMs, LLaVA-NeXT and OmniFusion. We find that both the main and residual streams for tokens of both modalities exhibit highly linear behaviors across transformer layers. However, LLaVA-NeXT's image tokens reveal a slight decline in linearity, whereas OmniFusion's remain consistent. Image token dimensions in OmniFusion remain consistently higher across layers compared to LLaVA-NeXT. Also, the OmniFusion's anisotropy is observed to stay consistently low throughout the layers. These findings suggest that the inner workings of MLLMs highly depend on the nature of modality fusion performed before passing the token sequence into LLM. This and other new potential insights obtainable from our system are surely capable of enhancing our understanding of the inner workings of MLLMs, informing future model design and optimization.
format Preprint
id arxiv_https___arxiv_org_abs_2606_00909
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MLLM-Microscope: Unlocking Hidden Structure Within Multimodal Large Language Models
Mussabayev, Ravil
Mussabayev, Rustam
Computation and Language
Artificial Intelligence
This work presents MLLM-Microscope, a novel system designed for analyzing the hidden representations within Multimodal Large Language Models (MLLMs). Our system evaluates the linearity, intrinsic dimension, and anisotropy of multimodal token embeddings across transformer layers. Utilizing the ScienceQA dataset, we evaluate two state-of-the-art MLLMs, LLaVA-NeXT and OmniFusion. We find that both the main and residual streams for tokens of both modalities exhibit highly linear behaviors across transformer layers. However, LLaVA-NeXT's image tokens reveal a slight decline in linearity, whereas OmniFusion's remain consistent. Image token dimensions in OmniFusion remain consistently higher across layers compared to LLaVA-NeXT. Also, the OmniFusion's anisotropy is observed to stay consistently low throughout the layers. These findings suggest that the inner workings of MLLMs highly depend on the nature of modality fusion performed before passing the token sequence into LLM. This and other new potential insights obtainable from our system are surely capable of enhancing our understanding of the inner workings of MLLMs, informing future model design and optimization.
title MLLM-Microscope: Unlocking Hidden Structure Within Multimodal Large Language Models
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2606.00909