Stories in Space: In-Context Learning Trajectories in Conceptual Belief Space

Fuente: arXiv
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Main Authors: Bigelow, Eric, Sarfati, Raphaël, Wurgaft, Daniel, Lewis, Owen, McGrath, Thomas, Merullo, Jack, Geiger, Atticus, Lubana, Ekdeep Singh
Format: Preprint
Published: 2026
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author Bigelow, Eric
Sarfati, Raphaël
Wurgaft, Daniel
Lewis, Owen
McGrath, Thomas
Merullo, Jack
Geiger, Atticus
Lubana, Ekdeep Singh
author_facet Bigelow, Eric
Sarfati, Raphaël
Wurgaft, Daniel
Lewis, Owen
McGrath, Thomas
Merullo, Jack
Geiger, Atticus
Lubana, Ekdeep Singh
contents Large Language Models (LLMs) update their behavior in context, which can be viewed as a form of Bayesian inference. However, the structure of the latent hypothesis space over which this inference operates remains unclear. In this work, we propose that LLMs assign beliefs over a low-dimensional geometric space - a conceptual belief space - and that in-context learning corresponds to a trajectory through this space as beliefs are updated over time. Using story understanding as a natural setting for dynamic belief updating, we combine behavioral and representational analyses to study these trajectories. We find that (1) belief updates are well-described as trajectories on low-dimensional, structured manifolds; (2) this structure is reflected consistently in both model behavior and internal representations and can be decoded with simple linear probes to predict behavior; and (3) interventions on these representations causally steer belief trajectories, with effects that can be predicted from the geometry of the conceptual space. Together, our results provide a geometric account of belief dynamics in LLMs, grounding Bayesian interpretations of in-context learning in structured conceptual representations.
format Preprint
id arxiv_https___arxiv_org_abs_2605_12412
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Stories in Space: In-Context Learning Trajectories in Conceptual Belief Space
Bigelow, Eric
Sarfati, Raphaël
Wurgaft, Daniel
Lewis, Owen
McGrath, Thomas
Merullo, Jack
Geiger, Atticus
Lubana, Ekdeep Singh
Computation and Language
Artificial Intelligence
Machine Learning
Large Language Models (LLMs) update their behavior in context, which can be viewed as a form of Bayesian inference. However, the structure of the latent hypothesis space over which this inference operates remains unclear. In this work, we propose that LLMs assign beliefs over a low-dimensional geometric space - a conceptual belief space - and that in-context learning corresponds to a trajectory through this space as beliefs are updated over time. Using story understanding as a natural setting for dynamic belief updating, we combine behavioral and representational analyses to study these trajectories. We find that (1) belief updates are well-described as trajectories on low-dimensional, structured manifolds; (2) this structure is reflected consistently in both model behavior and internal representations and can be decoded with simple linear probes to predict behavior; and (3) interventions on these representations causally steer belief trajectories, with effects that can be predicted from the geometry of the conceptual space. Together, our results provide a geometric account of belief dynamics in LLMs, grounding Bayesian interpretations of in-context learning in structured conceptual representations.
title Stories in Space: In-Context Learning Trajectories in Conceptual Belief Space
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2605.12412