We address the Continual Learning (CL) problem, where a model has to learn a sequence of tasks from non-stationary distributions while preserving prior knowledge as it encounters new experiences. With the advancement of foundation models, CL research has shifted focus from the initial learning-from-scratch paradigm to the use of generic features from large-scale pre-training. However, existing approaches to CL with pre-trained models only focus on separating the class-specific features from the final representation layer and neglect the power of intermediate representations that capture low- and mid-level features naturally more invariant to domain shifts. In this work, we propose LayUP, a new class-prototype-based approach to continual learning that leverages second-order feature statistics from multiple intermediate layers of a pre-trained network. Our method is conceptually simple, does not require any replay buffer, and works out of the box with any foundation model. LayUP improves over the state-of-the-art on four of the seven class-incremental learning settings at a considerably reduced memory and computational footprint compared with the next best baseline. Our results demonstrate that fully exhausting the representational capacities of pre-trained models in CL goes far beyond their final embeddings.

我们提出了LayUP，这是一种基于类原型的持续学习方法，利用预训练网络的多个中间层的二阶特征统计。与最佳基准线相比，LayUP在七种类增量学习设置中提高了四种，并且在内存和计算资源占用方面大大减少。我们的结果表明，充分利用预训练模型在持续学习中的表示能力远不止于最终嵌入。

跨层表示优化预训练模型的无需重演训练的持续学习