CAST: Cross-modal Alignment Similarity Test for Vision Language Models

Gautier Dagan, Olga Loginova, Anil Batra


Abstract
Vision Language Models (VLMs) are typically evaluated with Visual Question Answering (VQA) tasks which assess a model’s understanding of scenes. Good VQA performance is taken as evidence that the model will perform well on a broader range of tasks that require both visual and language inputs. However, scene-aware VQA does not fully capture input biases or assess hallucinations caused by a misalignment between modalities. To address this, we propose a Cross-modal Alignment Similarity Test (CAST) to probe VLMs for self-consistency across modalities. This test involves asking the models to identify similarities between two scenes through text-only, image-only, or both and then assess the truthfulness of the similarities they generate. Since there is no ground-truth to compare against, this evaluation does not focus on objective accuracy but rather on whether VLMs are internally consistent in their outputs. We argue that while not all self-consistent models are capable or accurate, all capable VLMs must be self-consistent.
Anthology ID:
2025.coling-main.93
Volume:
Proceedings of the 31st International Conference on Computational Linguistics
Month:
January
Year:
2025
Address:
Abu Dhabi, UAE
Editors:
Owen Rambow, Leo Wanner, Marianna Apidianaki, Hend Al-Khalifa, Barbara Di Eugenio, Steven Schockaert
Venue:
COLING
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1387–1402
Language:
URL:
https://aclanthology.org/2025.coling-main.93/
DOI:
Bibkey:
Cite (ACL):
Gautier Dagan, Olga Loginova, and Anil Batra. 2025. CAST: Cross-modal Alignment Similarity Test for Vision Language Models. In Proceedings of the 31st International Conference on Computational Linguistics, pages 1387–1402, Abu Dhabi, UAE. Association for Computational Linguistics.
Cite (Informal):
CAST: Cross-modal Alignment Similarity Test for Vision Language Models (Dagan et al., COLING 2025)
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PDF:
https://aclanthology.org/2025.coling-main.93.pdf