  Recent research has shown that large language models rely on spurious
correlations in the data for natural language understanding (NLU) tasks. In
this work, we aim to answer the following research question: Can we reduce
spurious correlations by modifying the ground truth labels of the training
data? Specifically, we propose a simple yet effective debiasing framework,
named Soft Label Encoding (SoftLE). We first train a teacher model with hard
labels to determine each sample's degree of relying on shortcuts. We then add
one dummy class to encode the shortcut degree, which is used to smooth other
dimensions in the ground truth label to generate soft labels. This new ground
truth label is used to train a more robust student model. Extensive experiments
on two NLU benchmark tasks demonstrate that SoftLE significantly improves
out-of-distribution generalization while maintaining satisfactory
in-distribution accuracy.
