Paper Detail

Switch-Reasoner: Learn When to Think in Multitask Mixtures via Reinforcement Learning

Yiyang Fang, Pei Fu, Jinjie Li, Jian Liang, Wenke Huang, Ruijie Luo, Shaojie Zhang, Jian Luan, Yi R. Fung, Mang Ye

arxiv Score 16.3

Published 2026-07-09 · First seen 2026-07-10

General AI

Abstract

Multimodal Large Language Models (MLLMs) often follow a fixed Think-then-Answer paradigm, which is inefficient in heterogeneous multitask settings because simple inputs may not require explicit reasoning while difficult ones can benefit substantially from it. Learning when to think is also unstable during post-training, where imbalanced rollouts can drive the model toward always-thinking or always-direct behavior. We propose Switch-Reasoner, a GRPO-based framework that learns to adaptively select reasoning modes for MLLMs. It treats thinking as a virtual tool invocation and allows the model to either answer directly or invoke explicit reasoning before answering. To stabilize this decision, we introduce a dual-level regulation mechanism that balances the overall use of Thinking Mode and Direct Mode while providing sample-level supervision based on the relative benefit of the two choices. Experiments on 11 multimodal tasks show that Switch-Reasoner reduces unnecessary reasoning while maintaining strong performance, achieving a better accuracy-efficiency trade-off.

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BibTeX

@article{fang2026switch,
  title = {Switch-Reasoner: Learn When to Think in Multitask Mixtures via Reinforcement Learning},
  author = {Yiyang Fang and Pei Fu and Jinjie Li and Jian Liang and Wenke Huang and Ruijie Luo and Shaojie Zhang and Jian Luan and Yi R. Fung and Mang Ye},
  year = {2026},
  abstract = {Multimodal Large Language Models (MLLMs) often follow a fixed Think-then-Answer paradigm, which is inefficient in heterogeneous multitask settings because simple inputs may not require explicit reasoning while difficult ones can benefit substantially from it. Learning when to think is also unstable during post-training, where imbalanced rollouts can drive the model toward always-thinking or always-direct behavior. We propose Switch-Reasoner, a GRPO-based framework that learns to adaptively selec},
  url = {https://arxiv.org/abs/2607.08572},
  keywords = {cs.CV},
  eprint = {2607.08572},
  archiveprefix = {arXiv},
}

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