Probabilistic Attention Based on Gaussian Processes for Deep Multiple Instance Learning

Arne Schmidt, Pablo Morales-Alvarez, Rafael Molina

Abstract:

Multiple Instance Learning (MIL) is a weakly supervised learning paradigm that is becoming increasingly popular because it requires less labeling effort than fully supervised methods. This is
especially interesting for areas where the creation of large annotated datasets remains challenging,
as in medicine. Although recent deep learning MIL approaches have obtained state-of-the-art results, they are fully deterministic and do not provide uncertainty estimations for the predictions. In
this work, we introduce the Attention Gaussian Process (AGP) model, a novel probabilistic attention
mechanism based on Gaussian Processes for deep MIL. AGP provides accurate bag-level predictions
as well as instance-level explainability, and can be trained end-to-end. Moreover, its probabilistic
nature guarantees robustness to overfitting on small datasets and uncertainty estimations for the predictions. The latter is especially important in medical applications, where decisions have a direct
impact on the patient’s health. The proposed model is validated experimentally as follows. First,
its behavior is illustrated in two synthetic MIL experiments based on the well-known MNIST and
CIFAR-10 datasets, respectively. Then, it is evaluated in three different real-world cancer detection experiments. AGP outperforms state-of-the-art MIL approaches, including deterministic deep
learning ones. It shows a strong performance even on a small dataset with less than 100 labels and
generalizes better than competing methods on an external test set. Moreover, we experimentally
show that predictive uncertainty correlates with the risk of wrong predictions, and therefore it is a
good indicator of reliability in practice. Our code is publicly available.