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Main Authors: Kwon, Yongchan, Zhu, Shang, Bianchi, Federico, Zhou, Kaitlyn, Zou, James
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2510.15211
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author Kwon, Yongchan
Zhu, Shang
Bianchi, Federico
Zhou, Kaitlyn
Zou, James
author_facet Kwon, Yongchan
Zhu, Shang
Bianchi, Federico
Zhou, Kaitlyn
Zou, James
contents The ability of large language models (LLMs) to follow user instructions is central to their reliability, safety, and usefulness. While prior studies assess instruction adherence in the model's main responses, we argue that it is also critical for large reasoning models (LRMs) to follow user instructions throughout their reasoning process. Reasoning instruction following makes LRMs more controllable and transparent, while reducing risks of undesirable shortcuts, hallucinations, or reward hacking within reasoning traces. To evaluate this dimension, we introduce ReasonIF, a systematic benchmark for assessing reasoning instruction following. ReasonIF includes six categories of instruction prompts, spanning multilingual reasoning, formatting and length control. Across many open-source LRMs including GPT-OSS, Qwen3, and DeepSeek-R1, we find substantial failures in reasoning instruction adherence: the highest instruction following score (IFS) remains below 0.25, meaning that fewer than $25\%$ of reasoning traces comply with the given instructions. Notably, as task difficulty increases, reasoning instruction following degrades further. We also explore two strategies to enhance reasoning instruction fidelity. (1) multi-turn reasoning and (2) Reasoning Instruction Finetuning (RIF) using synthetic data. RIF improves the IFS of $GPT-OSS-20B$ from 0.11 to 0.27, indicating measurable progress but leaving ample room for improvement.
format Preprint
id arxiv_https___arxiv_org_abs_2510_15211
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle ReasonIF: Large Reasoning Models Fail to Follow Instructions During Reasoning
Kwon, Yongchan
Zhu, Shang
Bianchi, Federico
Zhou, Kaitlyn
Zou, James
Machine Learning
Artificial Intelligence
The ability of large language models (LLMs) to follow user instructions is central to their reliability, safety, and usefulness. While prior studies assess instruction adherence in the model's main responses, we argue that it is also critical for large reasoning models (LRMs) to follow user instructions throughout their reasoning process. Reasoning instruction following makes LRMs more controllable and transparent, while reducing risks of undesirable shortcuts, hallucinations, or reward hacking within reasoning traces. To evaluate this dimension, we introduce ReasonIF, a systematic benchmark for assessing reasoning instruction following. ReasonIF includes six categories of instruction prompts, spanning multilingual reasoning, formatting and length control. Across many open-source LRMs including GPT-OSS, Qwen3, and DeepSeek-R1, we find substantial failures in reasoning instruction adherence: the highest instruction following score (IFS) remains below 0.25, meaning that fewer than $25\%$ of reasoning traces comply with the given instructions. Notably, as task difficulty increases, reasoning instruction following degrades further. We also explore two strategies to enhance reasoning instruction fidelity. (1) multi-turn reasoning and (2) Reasoning Instruction Finetuning (RIF) using synthetic data. RIF improves the IFS of $GPT-OSS-20B$ from 0.11 to 0.27, indicating measurable progress but leaving ample room for improvement.
title ReasonIF: Large Reasoning Models Fail to Follow Instructions During Reasoning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2510.15211