Emergent Search and Backtracking in Latent Reasoning Models

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Authors: Jasmine Jisong Cui, Charles Ye
Cited by: 0

Abstract

What happens when a language model thinks without words? Standard reasoning LLMs verbalize intermediate steps as chain-of-thought; latent reasoning transformers (LRTs) instead perform deliberation entirely in continuous hidden space. We investigate an LRT, decoding the model's evolving beliefs at every step on a multiple-choice QA benchmark. We find that the model spontaneously learns a structured search process in latent space. Deliberation follows a consistent trajectory: an exploration phase where probability mass spreads across candidates, tentative commitment to a frontrunner, and either convergence or backtracking. Backtracking is prevalent (32% of instances), beneficial (34% accuracy gain over non-backtracking instances), and predominantly directed away from the semantically closest distractor toward the correct answer. The search is adaptive: replacing distractors with implausible alternatives shortens exploration by 54%. Latent reasoning models achieve in activation space what chain-of-thought achieves through words: the ability to be wrong, notice, and recover.

Fields of Study & Subjects

Topic Modeling Natural Language Processing Techniques Explainable Artificial Intelligence (XAI)

Publication details

Journal / source
arXiv (Cornell University)
Publication date
8 February 2026
Language
EN
Document type
Preprint