Improving Automatic VQA Evaluation Using Large Language Models
Oscar Mañas, Benno Krojer, Aishwarya Agrawal
TL;DR
This work tackles the limited alignment of VQA Accuracy with human judgments in open-ended and OOD VQA. It introduces LAVE, an LLM-assisted evaluation metric that scores candidate answers against reference answers using in-context learning and provides rationales, mapped to a 0–1 score. Across multiple models and benchmarks, LAVE demonstrates superior correlation with human judgments compared to strong baselines, with thorough ablations showing robustness to design choices and clear guidance on practical deployment. The study also analyzes VQA Accuracy failure modes and shows LAVE can recover many missed correct answers, offering a more reliable and interpretable gauge of progress in vision-language QA.
Abstract
8 years after the visual question answering (VQA) task was proposed, accuracy remains the primary metric for automatic evaluation. VQA Accuracy has been effective so far in the IID evaluation setting. However, our community is undergoing a shift towards open-ended generative models and OOD evaluation. In this new paradigm, the existing VQA Accuracy metric is overly stringent and underestimates the performance of VQA systems. Thus, there is a need to develop more robust automatic VQA metrics that serve as a proxy for human judgment. In this work, we propose to leverage the in-context learning capabilities of instruction-tuned large language models (LLMs) to build a better VQA metric. We formulate VQA evaluation as an answer-rating task where the LLM is instructed to score the accuracy of a candidate answer given a set of reference answers. We demonstrate the proposed metric better correlates with human judgment compared to existing metrics across several VQA models and benchmarks. We hope wide adoption of our metric will contribute to better estimating the research progress on the VQA task. We plan to release the evaluation code and collected human judgments.
