Affordance20Q: Evaluating Affordance Reasoning from Physical Properties

Yifan Jiang, Meige Yang, Zitong Li, Jay Pujara


Abstract
Affordance reasoning, the inference of an object’s action possibilities from its physical properties (e.g., shape and material), is fundamental to human physical understanding and increasingly critical for Large Language Models (LLMs). However, existing affordance benchmarks largely expose explicit object identities in the evaluation setup, allowing models to rely on memorized object-affordance mappings rather than reasoning over physical properties. To address this gap, we introduce Affordance20Q, a novel affordance reasoning benchmark formulated as a 20-Questions game without exposing the object’s identity. In each game, the model identifies a hidden object’s affordance from a candidate set by asking yes/no questions about its physical properties. Affordance20Q comprises 1,009 games over 454 objects and 59 affordances, all manually filtered, refined, and annotated. We conduct comprehensive experiments with 15 state-of-the-art LLMs and find a substantial gap (~20 points) compared to human performance. A KL-based information-gain (IG) analysis further shows that models fail to ask discriminating questions as the game progresses. To close the gap, we develop KB-Anchored Rule Induction (KARI), a pipeline based on LLMs that generates affordance rules grounded in evidence from knowledge bases (KBs). KARI improves open-source LLMs by up to 15.2 points, while the limited coverage of KBs hinders further gains. We release all our code and data at https://github.com/1171-jpg/Affordance20Q.git.
Anthology ID:
2026.findings-emnlp.1683
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
35930–35948
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1683/
DOI:
10.18653/2026.findings-emnlp.1683
Bibkey:
Cite (ACL):
Yifan Jiang, Meige Yang, Zitong Li, and Jay Pujara. 2026. Affordance20Q: Evaluating Affordance Reasoning from Physical Properties. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 35930–35948, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Affordance20Q: Evaluating Affordance Reasoning from Physical Properties (Jiang et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.1683.pdf