Understanding the Transferability of Representations via Task-Relatedness
This addresses the need for better transferability estimation in machine learning, particularly for selecting pre-trained models, though it is incremental in providing a theoretical and empirical framework.
The paper tackles the problem of understanding when pre-trained models can be effectively transferred to downstream tasks by proposing a novel analysis that quantifies transferability in terms of task-relatedness, leading to an upper bound and showing high correlation with model accuracy in experiments on vision and language tasks.
The growing popularity of transfer learning, due to the availability of models pre-trained on vast amounts of data, makes it imperative to understand when the knowledge of these pre-trained models can be transferred to obtain high-performing models on downstream target tasks. However, the exact conditions under which transfer learning succeeds in a cross-domain cross-task setting are still poorly understood. To bridge this gap, we propose a novel analysis that analyzes the transferability of the representations of pre-trained models to downstream tasks in terms of their relatedness to a given reference task. Our analysis leads to an upper bound on transferability in terms of task-relatedness, quantified using the difference between the class priors, label sets, and features of the two tasks. Our experiments using state-of-the-art pre-trained models show the effectiveness of task-relatedness in explaining transferability on various vision and language tasks. The efficient computability of task-relatedness even without labels of the target task and its high correlation with the model's accuracy after end-to-end fine-tuning on the target task makes it a useful metric for transferability estimation. Our empirical results of using task-relatedness to select the best pre-trained model from a model zoo for a target task highlight its utility for practical problems.