PDL: Regularizing Multiple Instance Learning with Progressive Dropout Layers
Wenhui Zhu, Peijie Qiu, Xiwen Chen, Oana M. Dumitrascu, Yalin Wang
TL;DR
MIL models suffer from overfitting due to weak supervision. The paper presents Progressive Dropout Layer (PDL), a MIL-specific dropout with attention-based instance weighting and a progressive scheduler that regularizes the middle layer without altering MIL architectures. Across standard MIL benchmarks and WSIs, PDL yields consistent improvements in accuracy and localization, and analyses reveal effective drop-rate control and the scheduler's necessity. The work offers a practical, plug-in regularization tool that enhances weakly supervised learning and latent feature discovery in MIL.
Abstract
Multiple instance learning (MIL) was a weakly supervised learning approach that sought to assign binary class labels to collections of instances known as bags. However, due to their weak supervision nature, the MIL methods were susceptible to overfitting and required assistance in developing comprehensive representations of target instances. While regularization typically effectively combated overfitting, its integration with the MIL model has been frequently overlooked in prior studies. Meanwhile, current regularization methods for MIL have shown limitations in their capacity to uncover a diverse array of representations. In this study, we delve into the realm of regularization within the MIL model, presenting a novel approach in the form of a Progressive Dropout Layer (PDL). We aim to not only address overfitting but also empower the MIL model in uncovering intricate and impactful feature representations. The proposed method was orthogonal to existing MIL methods and could be easily integrated into them to boost performance. Our extensive evaluation across a range of MIL benchmark datasets demonstrated that the incorporation of the PDL into multiple MIL methods not only elevated their classification performance but also augmented their potential for weakly-supervised feature localizations.
