Abstract
In the domain of Visual Question Answering (VQA), studies have shown
improvement in users’ mental model of the VQA system when they are
exposed to examples of how these systems answer certain Image-Question
(IQ) pairs. In this work, we show that showing controlled counterfactual
image-question examples are more effective at improving the mental model
of users as compared to simply showing random examples. We compare a
generative approach and a retrieval-based approach to show
counterfactual examples. We use recent advances in generative
adversarial networks (GANs) to generate counterfactual images by
deleting and inpainting certain regions of interest in the image. We
then expose users to changes in the VQA system’s answer on those altered
images. To select the region of interest for inpainting, we experiment
with using both human-annotated attention maps and a fully automatic
method that uses the VQA system’s attention values. Finally, we test the
user’s mental model by asking them to predict the model’s performance on
a test counterfactual image. We note an overall improvement in users’
accuracy to predict answer change when shown counterfactual
explanations. While realistic retrieved counterfactuals obviously are
the most effective at improving the mental model, we show that a
generative approach can also be equally effective.