We introduce an evaluation methodology for visual question answering (VQA) to better diagnose cases of shortcut learning. These cases happen when a model exploits spurious statistical regularities to produce correct answers but does not actually deploy the desired behavior. There is a need to identify possible shortcuts in a dataset and assess their use before deploying a model in the real world. The research community in VQA has focused exclusively on question-based shortcuts, where a model might, for example, answer "What is the color of the sky" with "blue" by relying mostly on the question-conditional training prior and give little weight to visual evidence. We go a step further and consider multimodal shortcuts that involve both questions and images. We first identify potential shortcuts in the popular VQA v2 training set by mining trivial predictive rules such as co-occurrences of words and visual elements. We then create VQA-CE, a new evaluation set made of CounterExamples i.e. questions where the mined rules lead to incorrect answers. We use this new evaluation in a large-scale study of existing models. We demonstrate that even state-of-the-art models perform poorly and that existing techniques to reduce biases are largely ineffective in this context. Our findings suggest that past work on question-based biases in VQA has only addressed one facet of a complex issue. The code for our method is available at https://github.com/cdancette/detect-shortcuts

本文介绍了一个用于诊断视觉问答（VQA）模型中快速学习情况的评估方法，并提出了考虑问题和图片的多模态快捷方式问题。通过挖掘诸如词语和视觉元素的共现等规律等方法，首先在流行的VQA v2训练集中确定了可能的快速方式，然后引入基于我们的CounterExamples子集的VQA-CounterExamples（VQA-CE）评估协议进行了大规模研究，发现即使是最先进的模型也难以处理这个复杂的问题。

超越基于问题偏见：对多模态快捷学习在视觉问答中的评估