EvA: Erasing Spurious Correlations with Activations

Spurious correlations often arise when models associate features strongly correlated with, but not causally related to, the label e.g. an image classifier associates bodies of water with ducks. To mitigate spurious correlations, existing methods focus on learning unbiased representation or incorporating additional information about the correlations during training. This work removes spurious correlations by ``Erasing with Activations'' (EvA). EvA learns class-specific spurious indicator on each channel for the fully connected layer of pretrained networks. By erasing spurious connections during re-weighting, EvA achieves state-of-the-art performance across diverse datasets (6.2\% relative gain on BAR and achieves 4.1\% on Waterbirds). For biased datasets without any information about the spurious correlations, EvA can outperform previous methods (4.8\% relative gain on Waterbirds) with 6 orders of magnitude less compute, highlighting its data and computational efficiency.