What to Learn, and How: Toward Effective Learning from Rationales.

Learning from rationales seeks to augment model training with human-provided rationales (i.e., a subset of input tokens) that justify those labels. While intuitive, this idea has proven elusive in practice. We make two observations about human rationales via empirical analyses: 1) maximizing predicted rationale accuracy is not necessarily the optimal objective for improving model performance; 2) human rationales vary in whether they provide sufficient information for the model to exploit for prediction, and we can use this variance to assess a dataset's potential improvement from learning from rationales. Building on these insights, we propose loss functions and learning strategies, and evaluate their effectiveness on three datasets with human rationales. Our results demonstrate consistent improvements over baselines in both label performance and rationale performance, including a 3% accuracy improvement on MultiRC. Our work highlights the importance of understanding properties of human explanations and exploiting them accordingly in model training.