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Bayesian Data Reweighting Improves Multimodal Retrieval for Knowledge-Based Visual Question Answering

2026/08/03 by Jingchen Sun, Shaobo Han, Ruiyi Zhang +5
Computer Science · #cs.LG

paper · pdf

arxiv created 2026/08/03 · arxiv updated 2026/08/05

Abstract

Multimodal retrievers are essential for knowledge-based visual question answering, where they retrieve external evidence for image-question pairs. However, existing contrastive training methods typically treat all unmatched query-document pairs as equally informative negatives, which is problematic because many unmatched documents may still be semantically relevant or partially useful. We propose Bayesian Data Reweighting, a probabilistic framework that models query-document importance as latent variables and adaptively infers posterior weights to downweight likely false negatives. With closed-form posterior updates under conjugate priors and stochastic EM optimization, our method consistently improves retrieval accuracy across three retrievers and seven knowledge-based VQA benchmarks.

Citations