The Thinking Spectrum: An Empirical Study of Tunable Reasoning in LLMs through Model Merging

Fuente: arXiv
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Hauptverfasser: Lan, Xiaochong, Zheng, Yu, Cao, Shiteng, Li, Yong
Format: Preprint
Veröffentlicht: 2025
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author Lan, Xiaochong
Zheng, Yu
Cao, Shiteng
Li, Yong
author_facet Lan, Xiaochong
Zheng, Yu
Cao, Shiteng
Li, Yong
contents The growing demand for large language models (LLMs) with tunable reasoning capabilities in many real-world applications highlights a critical need for methods that can efficiently produce a spectrum of models balancing reasoning depth and computational cost. Model merging has emerged as a promising, training-free technique to address this challenge by arithmetically combining the weights of a general-purpose model with a specialized reasoning model. While various merging techniques exist, their potential to create a spectrum of models with fine-grained control over reasoning abilities remains largely unexplored. This work presents a large-scale empirical study evaluating a range of model merging techniques across multiple reasoning benchmarks. We systematically vary merging strengths to construct accuracy-efficiency curves, providing the first comprehensive view of the tunable performance landscape. Our findings reveal that model merging offers an effective and controllable method for calibrating the trade-off between reasoning accuracy and token efficiency, even when parent models have highly divergent weight spaces. Crucially, we identify instances of Pareto Improvement, where a merged model achieves both higher accuracy and lower token consumption than one of its parents. Our study provides the first comprehensive analysis of this tunable space, offering practical guidelines for creating LLMs with specific reasoning profiles to meet diverse application demands.
format Preprint
id arxiv_https___arxiv_org_abs_2509_22034
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Thinking Spectrum: An Empirical Study of Tunable Reasoning in LLMs through Model Merging
Lan, Xiaochong
Zheng, Yu
Cao, Shiteng
Li, Yong
Artificial Intelligence
Computation and Language
The growing demand for large language models (LLMs) with tunable reasoning capabilities in many real-world applications highlights a critical need for methods that can efficiently produce a spectrum of models balancing reasoning depth and computational cost. Model merging has emerged as a promising, training-free technique to address this challenge by arithmetically combining the weights of a general-purpose model with a specialized reasoning model. While various merging techniques exist, their potential to create a spectrum of models with fine-grained control over reasoning abilities remains largely unexplored. This work presents a large-scale empirical study evaluating a range of model merging techniques across multiple reasoning benchmarks. We systematically vary merging strengths to construct accuracy-efficiency curves, providing the first comprehensive view of the tunable performance landscape. Our findings reveal that model merging offers an effective and controllable method for calibrating the trade-off between reasoning accuracy and token efficiency, even when parent models have highly divergent weight spaces. Crucially, we identify instances of Pareto Improvement, where a merged model achieves both higher accuracy and lower token consumption than one of its parents. Our study provides the first comprehensive analysis of this tunable space, offering practical guidelines for creating LLMs with specific reasoning profiles to meet diverse application demands.
title The Thinking Spectrum: An Empirical Study of Tunable Reasoning in LLMs through Model Merging
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2509.22034