  Training on only perfect Standard English corpora predisposes pre-trained
neural networks to discriminate against minorities from non-standard linguistic
backgrounds (e.g., African American Vernacular English, Colloquial Singapore
English, etc.). We perturb the inflectional morphology of words to craft
plausible and semantically similar adversarial examples that expose these
biases in popular NLP models, e.g., BERT and Transformer, and show that
adversarially fine-tuning them for a single epoch significantly improves
robustness without sacrificing performance on clean data.
