In plain words: A new test checks only the language-model half of a robot's brain—the part that plans and reasons—on messy real-world tasks. The best models solved just 40%, far below the human average, and extra training for physical reasoning did not help.
Abstract
We present Butter-Bench, a benchmark evaluating large language model (LLM) controlled robots for practical intelligence, defined as the ability to navigate the messiness of the physical world. Current state-of-the-art robotic systems use a hierarchical architecture with LLMs in charge of high-level reasoning, and a Vision Language Action (VLA) model for low-level control. Butter-Bench evaluates the LLM part in isolation from the VLA. Although LLMs have repeatedly surpassed humans in evaluations requiring analytical intelligence, we find humans still outperform LLMs on Butter-Bench. The best LLMs score 40% on Butter-Bench, while the mean human score is 95%. LLMs struggled the most with multi-step spatial planning and social understanding. We also evaluate LLMs that are fine-tuned for embodied reasoning and conclude that this training does not improve their score on Butter-Bench.
Callum Sharrock, Lukas Petersson, Hanna Petersson, Axel Backlund, Axel Wennström, Kristoffer Nordström, Elias Aronsson
arXiv:2510.21860 · cs.RO, cs.AI · submitted Oct 23, 2025
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