Diagnosing Pathological Chain-of-Thought in Reasoning Models

Fuente: arXiv
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Hauptverfasser: Liu, Manqing, Williams-King, David, Caspary, Ida, Le, Linh, Whittingham, Hannes, Radmard, Puria, Tice, Cameron, Young, Edward James
Format: Preprint
Veröffentlicht: 2026
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author Liu, Manqing
Williams-King, David
Caspary, Ida
Le, Linh
Whittingham, Hannes
Radmard, Puria
Tice, Cameron
Young, Edward James
author_facet Liu, Manqing
Williams-King, David
Caspary, Ida
Le, Linh
Whittingham, Hannes
Radmard, Puria
Tice, Cameron
Young, Edward James
contents Chain-of-thought (CoT) reasoning is fundamental to modern LLM architectures and represents a critical intervention point for AI safety. However, CoT reasoning may exhibit failure modes that we note as pathologies, which prevent it from being useful for monitoring. Prior work has identified three distinct pathologies: post-hoc rationalization, where models generate plausible explanations backwards from predetermined answers; encoded reasoning, where intermediate steps conceal information within seemingly interpretable text; and internalized reasoning, where models replace explicit reasoning with meaningless filler tokens while computing internally. To better understand and discriminate between these pathologies, we create a set of concrete metrics that are simple to implement, computationally inexpensive, and task-agnostic. To validate our approach, we develop model organisms deliberately trained to exhibit specific CoT pathologies. Our work provides a practical toolkit for assessing CoT pathologies, with direct implications for training-time monitoring.
format Preprint
id arxiv_https___arxiv_org_abs_2602_13904
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Diagnosing Pathological Chain-of-Thought in Reasoning Models
Liu, Manqing
Williams-King, David
Caspary, Ida
Le, Linh
Whittingham, Hannes
Radmard, Puria
Tice, Cameron
Young, Edward James
Artificial Intelligence
Chain-of-thought (CoT) reasoning is fundamental to modern LLM architectures and represents a critical intervention point for AI safety. However, CoT reasoning may exhibit failure modes that we note as pathologies, which prevent it from being useful for monitoring. Prior work has identified three distinct pathologies: post-hoc rationalization, where models generate plausible explanations backwards from predetermined answers; encoded reasoning, where intermediate steps conceal information within seemingly interpretable text; and internalized reasoning, where models replace explicit reasoning with meaningless filler tokens while computing internally. To better understand and discriminate between these pathologies, we create a set of concrete metrics that are simple to implement, computationally inexpensive, and task-agnostic. To validate our approach, we develop model organisms deliberately trained to exhibit specific CoT pathologies. Our work provides a practical toolkit for assessing CoT pathologies, with direct implications for training-time monitoring.
title Diagnosing Pathological Chain-of-Thought in Reasoning Models
topic Artificial Intelligence
url https://arxiv.org/abs/2602.13904