Continual Learning via Learning a Continual Memory in Vision Transformer (2303.08250v4)

Abstract: This paper studies task-incremental continual learning (TCL) using Vision Transformers (ViTs). Our goal is to improve the overall streaming-task performance without catastrophic forgetting by learning task synergies (e.g., a new task learns to automatically reuse/adapt modules from previous similar tasks, or to introduce new modules when needed, or to skip some modules when it appears to be an easier task). One grand challenge is how to tame ViTs at streaming diverse tasks in terms of balancing their plasticity and stability in a task-aware way while overcoming the catastrophic forgetting. To address the challenge, we propose a simple yet effective approach that identifies a lightweight yet expressive ``sweet spot'' in the ViT block as the task-synergy memory in TCL. We present a Hierarchical task-synergy Exploration-Exploitation (HEE) sampling based neural architecture search (NAS) method for effectively learning task synergies by structurally updating the identified memory component with respect to four basic operations (reuse, adapt, new and skip) at streaming tasks. The proposed method is thus dubbed as CHEEM (Continual Hierarchical-Exploration-Exploitation Memory). In experiments, we test the proposed CHEEM on the challenging Visual Domain Decathlon (VDD) benchmark and the 5-Dataset benchmark. It obtains consistently better performance than the prior art with sensible CHEEM learned continually.