Mihir Parmar, Nisarg Patel, Neeraj Varshney, Mutsumi Nakamura, Man Luo, Santosh Mashetty, Arindam Mitra, Chitta Baral. Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers). 2024.

We investigate knowledge retrieval with multimodal queries, i.e. queries containing information split across image and text inputs, a challenging task that differs from previous work on cross-modal retrieval.We curate a new dataset called ReMuQ 1 for benchmarking progress on this task.ReMuQ requires a system to retrieve knowledge from a large corpus by integrating contents from both text and image queries.We introduce a retriever model "ReViz" that can directly process input text and images to retrieve relevant knowledge in an end-to-end fashion without being dependent on intermediate modules such as object detectors or caption generators.We introduce a new pretraining task that is effective for learning knowledge retrieval with multimodal queries and also improves performance on downstream tasks.We demonstrate superior performance in retrieval on two datasets (ReMuQ and OK-VQA) under zeroshot settings as well as further improvements when finetuned on these datasets.

Information retrieval (IR) is essential in search engines and dialogue systems as well as natural language processing tasks such as open-domain question answering. IR serve an important function in the biomedical domain, where content and sources of scientific knowledge may evolve rapidly. Although neural retrievers have surpassed traditional IR approaches such as TF-IDF and BM25 in standard open-domain question answering tasks, they are still found lacking in the biomedical domain. In this paper, we seek to improve information retrieval (IR) using neural retrievers (NR) in the biomedical domain, and achieve this goal using a three-pronged approach. First, to tackle the relative lack of data in the biomedical domain, we propose a template-based question generation method that can be leveraged to train neural retriever models. Second, we develop two novel pre-training tasks that are closely aligned to the downstream task of information retrieval. Third, we introduce the ``Poly-DPR'' model which encodes each context into multiple context vectors. Extensive experiments and analysis on the BioASQ challenge suggest that our proposed method leads to large gains over existing neural approaches and beats BM25 in the small-corpus setting. We show that BM25 and our method can complement each other, and a simple hybrid model leads to further gains in the large corpus setting.

Man Luo, Shailaja Keyur Sampat, Riley Tallman, Yankai Zeng, Manuha Vancha, Akarshan Sajja, Chitta Baral. Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume. 2021.

Knowledge-based visual question answering (VQA) requires answering questions with external knowledge in addition to the content of images.One dataset that is mostly used in evaluating knowledge-based VQA is OK-VQA, but it lacks a gold standard knowledge corpus for retrieval.Existing work leverage different knowledge bases (e.g., ConceptNet and Wikipedia) to obtain external knowledge.Because of varying knowledge bases, it is hard to fairly compare models' performance.To address this issue, we collect a natural language knowledge base that can be used for any VQA system.Moreover, we propose a Visual Retriever-Reader pipeline to approach knowledge-based VQA.The visual retriever aims to retrieve relevant knowledge, and the visual reader seeks to predict answers based on given knowledge.We introduce various ways to retrieve knowledge using text and images and two reader styles: classification and extraction.Both the retriever and reader are trained with weak supervision.Our experimental results show that a good retriever can significantly improve the reader's performance on the OK-VQA challenge.The code and corpus are provided in this link.