What's the plan? Metrics for implicit planning in LLMs and their application to rhyme generation and question answering

Fuente: arXiv
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Auteurs principaux: Maar, Jim, Paperno, Denis, McDougall, Callum Stuart, Nanda, Neel
Format: Preprint
Publié: 2026
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author Maar, Jim
Paperno, Denis
McDougall, Callum Stuart
Nanda, Neel
author_facet Maar, Jim
Paperno, Denis
McDougall, Callum Stuart
Nanda, Neel
contents Prior work suggests that language models, while trained on next token prediction, show implicit planning behavior: they may select the next token in preparation to a predicted future token, such as a likely rhyming word, as supported by a prior qualitative study of Claude 3.5 Haiku using a cross-layer transcoder. We propose much simpler techniques for assessing implicit planning in language models. With case studies on rhyme poetry generation and question answering, we demonstrate that our methodology easily scales to many models. Across models, we find that the generated rhyme (e.g. "-ight") or answer to a question ("whale") can be manipulated by steering at the end of the preceding line with a vector, affecting the generation of intermediate tokens leading up to the rhyme or answer word. We show that implicit planning is a universal mechanism, present in smaller models than previously thought, starting from 1B parameters. Our methodology offers a widely applicable direct way to study implicit planning abilities of LLMs. More broadly, understanding planning abilities of language models can inform decisions in AI safety and control.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20164
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle What's the plan? Metrics for implicit planning in LLMs and their application to rhyme generation and question answering
Maar, Jim
Paperno, Denis
McDougall, Callum Stuart
Nanda, Neel
Machine Learning
Artificial Intelligence
Computation and Language
Prior work suggests that language models, while trained on next token prediction, show implicit planning behavior: they may select the next token in preparation to a predicted future token, such as a likely rhyming word, as supported by a prior qualitative study of Claude 3.5 Haiku using a cross-layer transcoder. We propose much simpler techniques for assessing implicit planning in language models. With case studies on rhyme poetry generation and question answering, we demonstrate that our methodology easily scales to many models. Across models, we find that the generated rhyme (e.g. "-ight") or answer to a question ("whale") can be manipulated by steering at the end of the preceding line with a vector, affecting the generation of intermediate tokens leading up to the rhyme or answer word. We show that implicit planning is a universal mechanism, present in smaller models than previously thought, starting from 1B parameters. Our methodology offers a widely applicable direct way to study implicit planning abilities of LLMs. More broadly, understanding planning abilities of language models can inform decisions in AI safety and control.
title What's the plan? Metrics for implicit planning in LLMs and their application to rhyme generation and question answering
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2601.20164