@inproceedings{aswal-etal-2026-observable,
title = "Observable Patterns Are Not Explanations: A Causal-Geometric Analysis of Latent Reasoning Models",
author = "Aswal, Darpan and
Ferraz, Thomas Palmeira and
Zhou, Yongxin and
Peyrard, Maxime",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.83/",
pages = "1898--1938",
ISBN = "979-8-89176-459-0",
abstract = "Latent reasoning models (LRMs) replace explicit chain-of-thought with continuous thoughts. Recent work treats observable latent-state patterns, such as BFS-like frontiers and decodable arithmetic computation, as evidence for internal reasoning mechanisms. Evaluating two LRMs (Coconut and CODI) against controls lacking the proposed recurrence or curriculum, we find these patterns also appear in the controls and do not consistently affect behavior. Causal interventions reveal that latent-thought utilization is not binary but graded, scaling with a thought{'}s causal effect on model behavior. Geometric analyses reveal this effect concentrates in low-dimensional subspaces whose step-wise geometry grows more structured as their behavioral influence increases. Latent thoughts should therefore be treated as hidden computation, not hidden explanation: decodability, attention, or static structure alone cannot establish LRM reasoning mechanisms; that requires matched controls and causal tests."
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%0 Conference Proceedings
%T Observable Patterns Are Not Explanations: A Causal-Geometric Analysis of Latent Reasoning Models
%A Aswal, Darpan
%A Ferraz, Thomas Palmeira
%A Zhou, Yongxin
%A Peyrard, Maxime
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F aswal-etal-2026-observable
%X Latent reasoning models (LRMs) replace explicit chain-of-thought with continuous thoughts. Recent work treats observable latent-state patterns, such as BFS-like frontiers and decodable arithmetic computation, as evidence for internal reasoning mechanisms. Evaluating two LRMs (Coconut and CODI) against controls lacking the proposed recurrence or curriculum, we find these patterns also appear in the controls and do not consistently affect behavior. Causal interventions reveal that latent-thought utilization is not binary but graded, scaling with a thought’s causal effect on model behavior. Geometric analyses reveal this effect concentrates in low-dimensional subspaces whose step-wise geometry grows more structured as their behavioral influence increases. Latent thoughts should therefore be treated as hidden computation, not hidden explanation: decodability, attention, or static structure alone cannot establish LRM reasoning mechanisms; that requires matched controls and causal tests.
%U https://aclanthology.org/2026.emnlp-main.83/
%P 1898-1938
Markdown (Informal)
[Observable Patterns Are Not Explanations: A Causal-Geometric Analysis of Latent Reasoning Models](https://aclanthology.org/2026.emnlp-main.83/) (Aswal et al., EMNLP 2026)
ACL