Towards a Unified Model for Generating Answers and Explanations in Visual Question Answering

Providing explanations for visual question answering (VQA) has gained much attention in research. However, most existing systems use separate models for predicting answers and providing explanations. We argue that training explanation models independently of the QA model makes the explanations less grounded and limits performance. To address this, we propose a multitask learning approach towards a Unified Model for more grounded and consistent generation of both Answers and Explanations (UMAE). To achieve this, we add artificial prompt tokens to training instances and finetune a multimodal encoder-decoder model on various VQA tasks. In our experiments, UMAE models surpass the prior SOTA answer accuracy on A-OKVQA by 10~15%, show competitive results on OK-VQA, achieve new SOTA explanation scores on A-OKVQA and VCR, and demonstrate promising out-of-domain performance on VQA-X.