Grounded, or a Good Guesser? A Per-Question Balanced Dataset to Separate Blind from Grounded Models for Embodied Question Answering (forthcoming, ACL 2025)

Abstract: Embodied question answering (EQA) means using perception of and action in an environment to answer natural language questions about that environment. However, previous work has demonstrated that blind language models (which do not incorporate perception, but predict an answer based solely on the question text) are a strong baseline for existing benchmarks, even compared against state-of-the-art vision and language models.To determine whether a model is grounding its answers in its specific environment, rather than relying on a language model's expectations about the world generally, we propose PQB-EQA, a per-question balanced EQA dataset. In this new benchmark, every question appears twice, paired with two different environments that yield two different answers. That is, the answer distribution is balanced for each question, not just across the whole dataset. We show both theoretically and empirically that grounding in the environment is necessary to perform better than chance on PQB-EQA.