Exploring the System 1 Thinking Capability of Large Reasoning Models

Fuente: arXiv
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Main Authors: Zhang, Wenyuan, Nie, Shuaiyi, Zhang, Xinghua, Zhang, Zefeng, Liu, Tingwen
Format: Preprint
Published: 2025
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author Zhang, Wenyuan
Nie, Shuaiyi
Zhang, Xinghua
Zhang, Zefeng
Liu, Tingwen
author_facet Zhang, Wenyuan
Nie, Shuaiyi
Zhang, Xinghua
Zhang, Zefeng
Liu, Tingwen
contents This paper explores the system 1 thinking capability of Large Reasoning Models (LRMs), the intuitive ability to respond efficiently with minimal token usage. While existing LRMs rely on long-chain reasoning and excel at complex tasks, their system 1 thinking ability remains largely underexplored. This capability is essential as it reflects models' difficulty awareness and reasoning efficiency, both critical for real-world applications. We propose S1-Bench, a multi-domain, multilingual benchmark comprising model-simple system 1 questions. Our investigation of 28 LRMs reveals under-accuracy and inefficiency on system 1 problems. We find existing efficient reasoning methods either generalize poorly to simple questions or sacrifice performance for efficiency. Further exploration uncovers LRMs' early difficulty awareness accompanied by lower confidence, and shows that problem difficulty is implicitly encoded in hidden states.
format Preprint
id arxiv_https___arxiv_org_abs_2504_10368
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exploring the System 1 Thinking Capability of Large Reasoning Models
Zhang, Wenyuan
Nie, Shuaiyi
Zhang, Xinghua
Zhang, Zefeng
Liu, Tingwen
Computation and Language
Artificial Intelligence
This paper explores the system 1 thinking capability of Large Reasoning Models (LRMs), the intuitive ability to respond efficiently with minimal token usage. While existing LRMs rely on long-chain reasoning and excel at complex tasks, their system 1 thinking ability remains largely underexplored. This capability is essential as it reflects models' difficulty awareness and reasoning efficiency, both critical for real-world applications. We propose S1-Bench, a multi-domain, multilingual benchmark comprising model-simple system 1 questions. Our investigation of 28 LRMs reveals under-accuracy and inefficiency on system 1 problems. We find existing efficient reasoning methods either generalize poorly to simple questions or sacrifice performance for efficiency. Further exploration uncovers LRMs' early difficulty awareness accompanied by lower confidence, and shows that problem difficulty is implicitly encoded in hidden states.
title Exploring the System 1 Thinking Capability of Large Reasoning Models
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2504.10368