@inproceedings{kachaev-etal-2026-vla,
title = "Does {VLA} Even Know the Basics? Limitations in Commonsense and World Knowledge of {VLA} Models",
author = "Kachaev, Nikita and
Moskalenko, Andrey and
Skripkin, Matvey and
Kurlaev, Nikita and
Pugacheva, Daria and
Burlova, Albina and
Kolosov, Mikhail and
Shepelev, Denis and
Kuznetsov, Andrey and
Tutubalina, Elena and
Panov, Aleksandr and
Kovalev, Alexey and
Shakhuro, Vlad",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.1782/",
pages = "40600--40621",
ISBN = "979-8-89176-459-0",
abstract = "Embodied Vision{--}Language{--}Action (VLA) models are typically obtained by fine-tuning powerful pretrained VLMs on robotics data. Yet we do not know whether these agents still ``know the basics'' about the world after adaptation, nor how much commonsense and factual knowledge is preserved versus catastrophically forgotten. When a VLA fails on a knowledge-sensitive task, it is unclear whether the failure reflects degraded world knowledge or merely poor generalization of low-level control. We introduce Act2Answer, a lightweight protocol that adapts VLM knowledge benchmarks to VLA evaluation by requiring agents to act to answer. We map each benchmark question to a discrete embodied answer-selection decision in a controlled tabletop environment, where the agent answers via a single object-placement action into the region corresponding to its selected option, producing an action-grounded success rate with reduced control confounds. We introduce layerwise intent probing{--}linear classifiers on per-layer representations predicting the agent{'}s option selection{--}to localize answer-relevant information across model depth. Evaluating 9 state-of-the-art VLA models, we rank them across basic commonsense and world-knowledge categories and find that answer-relevant signals peak in middle VLM-backbone layers but attenuate in upper backbone layers and the action head."
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<abstract>Embodied Vision–Language–Action (VLA) models are typically obtained by fine-tuning powerful pretrained VLMs on robotics data. Yet we do not know whether these agents still “know the basics” about the world after adaptation, nor how much commonsense and factual knowledge is preserved versus catastrophically forgotten. When a VLA fails on a knowledge-sensitive task, it is unclear whether the failure reflects degraded world knowledge or merely poor generalization of low-level control. We introduce Act2Answer, a lightweight protocol that adapts VLM knowledge benchmarks to VLA evaluation by requiring agents to act to answer. We map each benchmark question to a discrete embodied answer-selection decision in a controlled tabletop environment, where the agent answers via a single object-placement action into the region corresponding to its selected option, producing an action-grounded success rate with reduced control confounds. We introduce layerwise intent probing–linear classifiers on per-layer representations predicting the agent’s option selection–to localize answer-relevant information across model depth. Evaluating 9 state-of-the-art VLA models, we rank them across basic commonsense and world-knowledge categories and find that answer-relevant signals peak in middle VLM-backbone layers but attenuate in upper backbone layers and the action head.</abstract>
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%0 Conference Proceedings
%T Does VLA Even Know the Basics? Limitations in Commonsense and World Knowledge of VLA Models
%A Kachaev, Nikita
%A Moskalenko, Andrey
%A Skripkin, Matvey
%A Kurlaev, Nikita
%A Pugacheva, Daria
%A Burlova, Albina
%A Kolosov, Mikhail
%A Shepelev, Denis
%A Kuznetsov, Andrey
%A Tutubalina, Elena
%A Panov, Aleksandr
%A Kovalev, Alexey
%A Shakhuro, Vlad
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F kachaev-etal-2026-vla
%X Embodied Vision–Language–Action (VLA) models are typically obtained by fine-tuning powerful pretrained VLMs on robotics data. Yet we do not know whether these agents still “know the basics” about the world after adaptation, nor how much commonsense and factual knowledge is preserved versus catastrophically forgotten. When a VLA fails on a knowledge-sensitive task, it is unclear whether the failure reflects degraded world knowledge or merely poor generalization of low-level control. We introduce Act2Answer, a lightweight protocol that adapts VLM knowledge benchmarks to VLA evaluation by requiring agents to act to answer. We map each benchmark question to a discrete embodied answer-selection decision in a controlled tabletop environment, where the agent answers via a single object-placement action into the region corresponding to its selected option, producing an action-grounded success rate with reduced control confounds. We introduce layerwise intent probing–linear classifiers on per-layer representations predicting the agent’s option selection–to localize answer-relevant information across model depth. Evaluating 9 state-of-the-art VLA models, we rank them across basic commonsense and world-knowledge categories and find that answer-relevant signals peak in middle VLM-backbone layers but attenuate in upper backbone layers and the action head.
%U https://aclanthology.org/2026.emnlp-main.1782/
%P 40600-40621
Markdown (Informal)
[Does VLA Even Know the Basics? Limitations in Commonsense and World Knowledge of VLA Models](https://aclanthology.org/2026.emnlp-main.1782/) (Kachaev et al., EMNLP 2026)
ACL
- Nikita Kachaev, Andrey Moskalenko, Matvey Skripkin, Nikita Kurlaev, Daria Pugacheva, Albina Burlova, Mikhail Kolosov, Denis Shepelev, Andrey Kuznetsov, Elena Tutubalina, Aleksandr Panov, Alexey Kovalev, and Vlad Shakhuro. 2026. Does VLA Even Know the Basics? Limitations in Commonsense and World Knowledge of VLA Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 40600–40621, Budapest, Hungary. Association for Computational Linguistics.