Online continual learning (CL) studies the problem of learning continuously from a single-pass data stream while adapting to new data and mitigating catastrophic forgetting. Recently, by storing a small subset of old data, replay-based methods have shown promising performance. Unlike previous methods that focus on sample storage or knowledge distillation against catastrophic forgetting, this paper aims to understand why the online learning models fail to generalize well from a new perspective of shortcut learning. We identify shortcut learning as the key limiting factor for online CL, where the learned features may be biased, not generalizable to new tasks, and may have an adverse impact on knowledge distillation. To tackle this issue, we present the online prototype learning (OnPro) framework for online CL. First, we propose online prototype equilibrium to learn representative features against shortcut learning and discriminative features to avoid class confusion, ultimately achieving an equilibrium status that separates all seen classes well while learning new classes. Second, with the feedback of online prototypes, we devise a novel adaptive prototypical feedback mechanism to sense the classes that are easily misclassified and then enhance their boundaries. Extensive experimental results on widely-used benchmark datasets demonstrate the superior performance of OnPro over the state-of-the-art baseline methods. Source code is available at https://github.com/weilllllls/OnPro.

在线连续学习中，通过在单通数据流中不断学习新数据并减轻灾难性遗忘的问题，本文分析了在新的学习任务中为何在线学习模型无法很好地泛化的快捷学习，然后提出了在线原型学习框架（OnPro），通过在线原型平衡和自适应原型反馈机制，达到良好分离所有已见类别、学习新类别的平衡状态，并在广泛使用的基准数据集上通过实验证明了OnPro相对于最先进的基准方法的卓越性能。

在线原型学习用于在线连续学习