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Internalized reasoning

Learn from worked solutions so that some or all of the reasoning can later happen without writing those steps. Training may use a separate teacher model or progressively remove written steps from the model being trained.

For example: A teacher model solves a problem in several written steps. A student model learns to produce the answer directly, using information from the teacher's intermediate reasoning during training.

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How the methods connect and differ

Distillation and stepwise internalization

Knowledge distillation and stepwise internalization use different training signals. Implicit CoT via Knowledge Distillation learns to predict a teacher's intermediate hidden states, which help a student produce the answer. Stepwise Internalization instead repeatedly shortens the written solution and fine-tunes the same model on what remains. Both use worked solutions during training; neither requires writing the removed steps at inference. Their reported experiments focus on multiplication and grade-school math, not a guarantee of general reasoning ability.

Sources: Deng et al. (2023), §3 · Deng et al. (2024), §3

Paper details: Implicit Chain of Thought Reasoning via Knowledge Distillation · From Explicit CoT to Implicit CoT: Learning to Internalize CoT Step by Step

Hidden-state distillation: the 2023 method and CODI

The 2023 implicit CoT paper proposes reasoning through hidden states and implements it with a teacher, a thought emulator and an answer-generating student. CODI also transfers explicit reasoning through hidden-state supervision, but uses one model for both teacher and student tasks. It aligns their states just before the answer, while the student takes successive continuous reasoning steps.

Sources: Deng et al. (2023), §2.3 · Deng et al. (2023), §3 · CODI, §3

Paper details: Implicit Chain of Thought Reasoning via Knowledge Distillation · CODI: Compressing Chain-of-Thought into Continuous Space via Self-Distillation

19 papers, oldest first

Dates usually refer to the first arXiv submission. Search or filter these papers →

arXiv

Implicit Chain of Thought Reasoning via Knowledge Distillation

Yuntian Deng, Kiran Prasad, Roland Fernandez, Paul Smolensky, Vishrav Chaudhary, Stuart Shieber

First proposes implicit chain-of-thought reasoning: learning to reason through continuous hidden states instead of generating explicit intermediate steps. Implements this framework by distilling an explicit-CoT teacher's intermediate representations into an emulator and a student that produces the answer.

Related terms: implicit CoT, latent reasoning, latent chain-of-thought, latent CoT.

Internalized reasoning
arXiv

Distilling System 2 into System 1

Ping Yu, Jing Xu, Jason Weston, Ilia Kulikov

Uses outputs from a slower deliberative process as training data for a faster model, studying when System-2-like behavior can be compressed into direct prediction.

Internalized reasoning
Paper ↗ Details & citations arXiv:2407.06023
arXiv

Efficient Reasoning with Hidden Thinking

Xuan Shen, Yizhou Wang, Yufa Zhou, Xiangxi Shi, Pu Zhao, Yanzhi Wang, Jiuxiang Gu

Compresses visible reasoning into hidden thinking states to reduce generated reasoning length while preserving task performance.

Internalized reasoningContinuous-state reasoning
Paper ↗ Details & citations arXiv:2501.19201
arXiv

LightThinker: Thinking Step-by-Step Compression

Jintian Zhang, Yuqi Zhu, Mengshu Sun, Yujie Luo, Shuofei Qiao, Lun Du, Da Zheng, Huajun Chen, Ningyu Zhang

Compresses segments of a generated reasoning chain into dense states while retaining a stepwise inference process.

Internalized reasoningContinuous-state reasoning
Paper ↗ Details & citations arXiv:2502.15589
arXiv

Chain Of Thought Compression: A Theoretical Analysis

Juncai Li, Ru Li, Yuxiang Zhou, Boxiang Ma, Jeff Z. Pan

Analyzes how skipping intermediate steps weakens learning signals in a simplified parity-task model. Introduces NatBool-DAG to test logical dependencies and ALiCoT, which supervises learned token states with intermediate logical labels or explicit-CoT representations.

Analysis and evaluationInternalized reasoningThinking tokens
Paper ↗ Details & citations arXiv:2601.21576
arXiv

Distilling Visual Reasoning into Text Space

Wenhan Yang, Nilay Naharas, Ali Payani, Baharan Mirzasoleiman

Distills a teacher's interleaved visual and textual reasoning into a student that no longer generates intermediate visual representations. The student still writes a textual chain of thought; what is internalized is the visual portion of the reasoning.

Internalized reasoning
Paper ↗ Details & citations arXiv:2609.34408