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Main Authors: Hong, Yihuai, Zhou, Dian, Cao, Meng, Yu, Lei, Jin, Zhijing
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2503.23084
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author Hong, Yihuai
Zhou, Dian
Cao, Meng
Yu, Lei
Jin, Zhijing
author_facet Hong, Yihuai
Zhou, Dian
Cao, Meng
Yu, Lei
Jin, Zhijing
contents Large language models (LLMs) excel on a variety of reasoning benchmarks, but previous studies suggest they sometimes struggle to generalize to unseen questions, potentially due to over-reliance on memorized training examples. However, the precise conditions under which LLMs switch between reasoning and memorization during text generation remain unclear. In this work, we provide a mechanistic understanding of LLMs' reasoning-memorization dynamics by identifying a set of linear features in the model's residual stream that govern the balance between genuine reasoning and memory recall. These features not only distinguish reasoning tasks from memory-intensive ones but can also be manipulated to causally influence model performance on reasoning tasks. Additionally, we show that intervening in these reasoning features helps the model more accurately activate the most relevant problem-solving capabilities during answer generation. Our findings offer new insights into the underlying mechanisms of reasoning and memory in LLMs and pave the way for the development of more robust and interpretable generative AI systems.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23084
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Reasoning-Memorization Interplay in Language Models Is Mediated by a Single Direction
Hong, Yihuai
Zhou, Dian
Cao, Meng
Yu, Lei
Jin, Zhijing
Computation and Language
Artificial Intelligence
Large language models (LLMs) excel on a variety of reasoning benchmarks, but previous studies suggest they sometimes struggle to generalize to unseen questions, potentially due to over-reliance on memorized training examples. However, the precise conditions under which LLMs switch between reasoning and memorization during text generation remain unclear. In this work, we provide a mechanistic understanding of LLMs' reasoning-memorization dynamics by identifying a set of linear features in the model's residual stream that govern the balance between genuine reasoning and memory recall. These features not only distinguish reasoning tasks from memory-intensive ones but can also be manipulated to causally influence model performance on reasoning tasks. Additionally, we show that intervening in these reasoning features helps the model more accurately activate the most relevant problem-solving capabilities during answer generation. Our findings offer new insights into the underlying mechanisms of reasoning and memory in LLMs and pave the way for the development of more robust and interpretable generative AI systems.
title The Reasoning-Memorization Interplay in Language Models Is Mediated by a Single Direction
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2503.23084