The Mechanistic Emergence of Symbol Grounding in Language Models

Fuente: arXiv
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Main Authors: Wu, Shuyu, Ma, Ziqiao, Luo, Xiaoxi, Huang, Yidong, Torres-Fonseca, Josue, Shi, Freda, Chai, Joyce
Format: Preprint
Published: 2025
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author Wu, Shuyu
Ma, Ziqiao
Luo, Xiaoxi
Huang, Yidong
Torres-Fonseca, Josue
Shi, Freda
Chai, Joyce
author_facet Wu, Shuyu
Ma, Ziqiao
Luo, Xiaoxi
Huang, Yidong
Torres-Fonseca, Josue
Shi, Freda
Chai, Joyce
contents Symbol grounding (Harnad, 1990) describes how symbols such as words acquire their meanings by connecting to real-world sensorimotor experiences. Recent work has shown preliminary evidence that grounding may emerge in (vision-)language models trained at scale without using explicit grounding objectives. Yet, the specific loci of this emergence and the mechanisms that drive it remain largely unexplored. To address this problem, we introduce a controlled evaluation framework that systematically traces how symbol grounding arises within the internal computations through mechanistic and causal analysis. Our findings show that grounding concentrates in middle-layer computations and is implemented through the aggregate mechanism, where attention heads aggregate the environmental ground to support the prediction of linguistic forms. This phenomenon replicates in multimodal dialogue and across architectures (Transformers and state-space models), but not in unidirectional LSTMs. Our results provide behavioral and mechanistic evidence that symbol grounding can emerge in language models, with practical implications for predicting and potentially controlling the reliability of generation.
format Preprint
id arxiv_https___arxiv_org_abs_2510_13796
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Mechanistic Emergence of Symbol Grounding in Language Models
Wu, Shuyu
Ma, Ziqiao
Luo, Xiaoxi
Huang, Yidong
Torres-Fonseca, Josue
Shi, Freda
Chai, Joyce
Computation and Language
Computer Vision and Pattern Recognition
Symbol grounding (Harnad, 1990) describes how symbols such as words acquire their meanings by connecting to real-world sensorimotor experiences. Recent work has shown preliminary evidence that grounding may emerge in (vision-)language models trained at scale without using explicit grounding objectives. Yet, the specific loci of this emergence and the mechanisms that drive it remain largely unexplored. To address this problem, we introduce a controlled evaluation framework that systematically traces how symbol grounding arises within the internal computations through mechanistic and causal analysis. Our findings show that grounding concentrates in middle-layer computations and is implemented through the aggregate mechanism, where attention heads aggregate the environmental ground to support the prediction of linguistic forms. This phenomenon replicates in multimodal dialogue and across architectures (Transformers and state-space models), but not in unidirectional LSTMs. Our results provide behavioral and mechanistic evidence that symbol grounding can emerge in language models, with practical implications for predicting and potentially controlling the reliability of generation.
title The Mechanistic Emergence of Symbol Grounding in Language Models
topic Computation and Language
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2510.13796