Mitigating Coordinate Prediction Bias from Positional Encoding Failures

Fuente: arXiv
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Hauptverfasser: Tao, Xingjian, Wang, Yiwei, Cai, Yujun, Luo, Yihong, Han, Kai, Tang, Jing
Format: Preprint
Veröffentlicht: 2025
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author Tao, Xingjian
Wang, Yiwei
Cai, Yujun
Luo, Yihong
Han, Kai
Tang, Jing
author_facet Tao, Xingjian
Wang, Yiwei
Cai, Yujun
Luo, Yihong
Han, Kai
Tang, Jing
contents While Multimodal Large Language Models (MLLMs) excel at general vision-language tasks, precise coordinate prediction remains a significant challenge, particularly as high-resolution inputs cause visual positional encodings (VPEs) to degrade. We demonstrate that these encoding failures do not result in random noise but instead trigger predictable, directional biases, suggesting that models default to internal spatial priors when grounding signals are weak. To counteract this, we introduce Vision-PE Shuffle Guidance (VPSG), a training-free, inference-time correction method. VPSG isolates position-unconditioned tendencies by shuffling VPEs and utilizes this negative evidence to steer digit decoding through a lightweight finite-state machine. Evaluation on the ScreenSpot-Pro benchmark confirms that VPSG effectively rectifies coordinate drift, yielding consistent improvements in localization accuracy across various model scales without any retraining. Our code is available at https://github.com/taoxj2001/VPSG.
format Preprint
id arxiv_https___arxiv_org_abs_2510_22102
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mitigating Coordinate Prediction Bias from Positional Encoding Failures
Tao, Xingjian
Wang, Yiwei
Cai, Yujun
Luo, Yihong
Han, Kai
Tang, Jing
Computer Vision and Pattern Recognition
Artificial Intelligence
Computation and Language
While Multimodal Large Language Models (MLLMs) excel at general vision-language tasks, precise coordinate prediction remains a significant challenge, particularly as high-resolution inputs cause visual positional encodings (VPEs) to degrade. We demonstrate that these encoding failures do not result in random noise but instead trigger predictable, directional biases, suggesting that models default to internal spatial priors when grounding signals are weak. To counteract this, we introduce Vision-PE Shuffle Guidance (VPSG), a training-free, inference-time correction method. VPSG isolates position-unconditioned tendencies by shuffling VPEs and utilizes this negative evidence to steer digit decoding through a lightweight finite-state machine. Evaluation on the ScreenSpot-Pro benchmark confirms that VPSG effectively rectifies coordinate drift, yielding consistent improvements in localization accuracy across various model scales without any retraining. Our code is available at https://github.com/taoxj2001/VPSG.
title Mitigating Coordinate Prediction Bias from Positional Encoding Failures
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2510.22102