The Grounding Gap: How LLMs Anchor the Meaning of Abstract Concepts Differently from Humans

Fuente: arXiv
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Auteurs principaux: Chlapanis, Odysseas S., Mastromichalakis, Orfeas Menis, Papadimitriou, Christos H.
Format: Preprint
Publié: 2026
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author Chlapanis, Odysseas S.
Mastromichalakis, Orfeas Menis
Papadimitriou, Christos H.
author_facet Chlapanis, Odysseas S.
Mastromichalakis, Orfeas Menis
Papadimitriou, Christos H.
contents Abstract concepts - justice, theory, availability - have no single perceivable referent; in the human brain, their meaning emerges from a web of experiences, affect, and social context. Do large language models (LLMs) ground abstract concepts in a similar way? We study this by replicating property-generation experiments from cognitive science on 21 frontier and open-weight LLMs. Across models and experiments, we find a consistent pattern: when compared to humans, models rely too heavily on word associations, and underproduce properties tied to emotion and internal states. This yields a large and consistent grounding gap: no model exceeds a Pearson correlation r=0.37 with human responses, compared to a human-to-human ceiling above r=0.9. To better interpret this gap, we also replicate a rating experiment on grounding categories and find that here LLMs align more closely with human judgment, and alignment improves as models get larger. We then use sparse autoencoders (SAEs) to inspect whether this information is also reflected in the models' internal features, and we do identify features connected to grounding dimensions such as "sensorimotor" and "social". These findings suggest that current LLMs can recover grounding dimensions when explicitly queried, but do not recruit them in a human-like way when words are generated freely.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08837
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Grounding Gap: How LLMs Anchor the Meaning of Abstract Concepts Differently from Humans
Chlapanis, Odysseas S.
Mastromichalakis, Orfeas Menis
Papadimitriou, Christos H.
Computation and Language
Artificial Intelligence
Abstract concepts - justice, theory, availability - have no single perceivable referent; in the human brain, their meaning emerges from a web of experiences, affect, and social context. Do large language models (LLMs) ground abstract concepts in a similar way? We study this by replicating property-generation experiments from cognitive science on 21 frontier and open-weight LLMs. Across models and experiments, we find a consistent pattern: when compared to humans, models rely too heavily on word associations, and underproduce properties tied to emotion and internal states. This yields a large and consistent grounding gap: no model exceeds a Pearson correlation r=0.37 with human responses, compared to a human-to-human ceiling above r=0.9. To better interpret this gap, we also replicate a rating experiment on grounding categories and find that here LLMs align more closely with human judgment, and alignment improves as models get larger. We then use sparse autoencoders (SAEs) to inspect whether this information is also reflected in the models' internal features, and we do identify features connected to grounding dimensions such as "sensorimotor" and "social". These findings suggest that current LLMs can recover grounding dimensions when explicitly queried, but do not recruit them in a human-like way when words are generated freely.
title The Grounding Gap: How LLMs Anchor the Meaning of Abstract Concepts Differently from Humans
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2605.08837