Grad2Task: Improved Few-shot Text Classification Using Gradients for Task Representation

Jixuan Wang, Kuan-Chieh Wang, Frank Rudzicz, Michael Brudno

Keywords: few-shot text classification, meta-learning, transfer learning, conditional neural process, transformer, pretrained language models

Abstract: Large pretrained language models (LMs) like BERT have improved performance in many disparate natural language processing (NLP) tasks. However, fine tuning such models requires a large number of training examples for each target task. Simultaneously, many realistic NLP problems are "few shot", without a sufficiently large training set. In this work, we propose a novel conditional neural process-based approach for few-shot text classification that learns to transfer from other diverse tasks with rich annotation. Our key idea is to represent each task using gradient information from a base model and to train an adaptation network that modulates a text classifier conditioned on the task representation. While previous task-aware few-shot learners represent tasks by input encoding, our novel task representation is more powerful, as the gradient captures input-output relationships of a task. Experimental results show that our approach outperforms traditional fine-tuning, sequential transfer learning, and state-of-the-art meta learning approaches on a collection of diverse few-shot tasks. We further conducted analysis and ablations to justify our design choices.

Code Of Conduct: I certify that all co-authors of this work have read and commit to adhering to the NeurIPS Statement on Ethics, Fairness, Inclusivity, and Code of Conduct.

TL;DR: We propose a novel model-based meta-learning approach for few-shot text classification using gradient information for task conditioning.

Code: https://github.com/jixuan-wang/Grad2Task