  Continual or lifelong learning has been a long-standing challenge in machine
learning to date, especially in natural language processing (NLP). Although
state-of-the-art language models such as BERT have ushered in a new era in this
field due to their outstanding performance in multitask learning scenarios,
they suffer from forgetting when being exposed to a continuous stream of data
with shifting data distributions. In this paper, we introduce DRILL, a novel
continual learning architecture for open-domain text classification. DRILL
leverages a biologically inspired self-organizing neural architecture to
selectively gate latent language representations from BERT in a
task-incremental manner. We demonstrate in our experiments that DRILL
outperforms current methods in a realistic scenario of imbalanced,
non-stationary data without prior knowledge about task boundaries. To the best
of our knowledge, DRILL is the first of its kind to use a self-organizing
neural architecture for open-domain lifelong learning in NLP.
