  Continual learning (CL) aims to constantly learn new knowledge over time
while avoiding catastrophic forgetting on old tasks. In this work, we focus on
continual text classification under the class-incremental setting. Recent CL
studies find that the representations learned in one task may not be effective
for other tasks, namely representation bias problem. For the first time we
formally analyze representation bias from an information bottleneck perspective
and suggest that exploiting representations with more class-relevant
information could alleviate the bias. To this end, we propose a novel
replay-based continual text classification method, RepCL. Our approach utilizes
contrastive and generative representation learning objectives to capture more
class-relevant features. In addition, RepCL introduces an adversarial replay
strategy to alleviate the overfitting problem of replay. Experiments
demonstrate that RepCL effectively alleviates forgetting and achieves
state-of-the-art performance on three text classification tasks.
