Revealing the Attention Floating Mechanism in Masked Diffusion Models

Fuente: arXiv
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Main Authors: Dai, Xin, Huang, Pengcheng, Liu, Zhenghao, Wang, Shuo, Yan, Yukun, Xiao, Chaojun, Gu, Yu, Yu, Ge, Sun, Maosong
Format: Preprint
Published: 2026
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_version_ 1866909988485595136
author Dai, Xin
Huang, Pengcheng
Liu, Zhenghao
Wang, Shuo
Yan, Yukun
Xiao, Chaojun
Gu, Yu
Yu, Ge
Sun, Maosong
author_facet Dai, Xin
Huang, Pengcheng
Liu, Zhenghao
Wang, Shuo
Yan, Yukun
Xiao, Chaojun
Gu, Yu
Yu, Ge
Sun, Maosong
contents Masked diffusion models (MDMs), which leverage bidirectional attention and a denoising process, are narrowing the performance gap with autoregressive models (ARMs). However, their internal attention mechanisms remain under-explored. This paper investigates the attention behaviors in MDMs, revealing the phenomenon of Attention Floating. Unlike ARMs, where attention converges to a fixed sink, MDMs exhibit dynamic, dispersed attention anchors that shift across denoising steps and layers. Further analysis reveals its Shallow Structure-Aware, Deep Content-Focused attention mechanism: shallow layers utilize floating tokens to build a global structural framework, while deeper layers allocate more capability toward capturing semantic content. Empirically, this distinctive attention pattern provides a mechanistic explanation for the strong in-context learning capabilities of MDMs, allowing them to double the performance compared to ARMs in knowledge-intensive tasks. All codes and datasets are available at https://github.com/NEUIR/Attention-Floating.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07894
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Revealing the Attention Floating Mechanism in Masked Diffusion Models
Dai, Xin
Huang, Pengcheng
Liu, Zhenghao
Wang, Shuo
Yan, Yukun
Xiao, Chaojun
Gu, Yu
Yu, Ge
Sun, Maosong
Machine Learning
Artificial Intelligence
Masked diffusion models (MDMs), which leverage bidirectional attention and a denoising process, are narrowing the performance gap with autoregressive models (ARMs). However, their internal attention mechanisms remain under-explored. This paper investigates the attention behaviors in MDMs, revealing the phenomenon of Attention Floating. Unlike ARMs, where attention converges to a fixed sink, MDMs exhibit dynamic, dispersed attention anchors that shift across denoising steps and layers. Further analysis reveals its Shallow Structure-Aware, Deep Content-Focused attention mechanism: shallow layers utilize floating tokens to build a global structural framework, while deeper layers allocate more capability toward capturing semantic content. Empirically, this distinctive attention pattern provides a mechanistic explanation for the strong in-context learning capabilities of MDMs, allowing them to double the performance compared to ARMs in knowledge-intensive tasks. All codes and datasets are available at https://github.com/NEUIR/Attention-Floating.
title Revealing the Attention Floating Mechanism in Masked Diffusion Models
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2601.07894