Data-Efficient Pretraining via Contrastive Self-Supervision
This addresses the challenge of data and compute efficiency for NLP practitioners with limited resources, though it is incremental as it builds on existing contrastive and self-supervised methods.
The paper tackles the problem of resource-efficient learning in NLP by proposing a contrastive self-supervised text encoder pretrained on only 60MB of task-internal data, which outperforms RoBERTa (pretrained on 160GB) while using one-fifth the fine-tuning time.
For natural language processing `text-to-text' tasks, the prevailing approaches heavily rely on pretraining large self-supervised models on increasingly larger `task-external' data. Transfer learning from high-resource pretraining works well, but research has focused on settings with very large data and compute requirements, while the potential of efficient low-resource learning, without large `task-external' pretraining, remains under-explored. In this work, we evaluate against three core challenges for resource efficient learning. Namely, we analyze: (1) pretraining data ($X$) efficiency; (2) zero to few-shot label ($Y$) efficiency; and (3) long-tail generalization, since long-tail preservation has been linked to algorithmic fairness and because data in the tail is limited by definition. To address these challenges, we propose a data and compute efficient self-supervised, contrastive text encoder, pretrained on 60MB of `task-internal' text data, and compare it to RoBERTa, which was pretrained on 160GB of `task-external' text. We find our method outperforms RoBERTa, while pretraining and fine-tuning in a 1/5th of RoBERTa's fine-tuning time.