---
id: "2022-01-28-chain-of-thought"
url: "https://postcutoff.com/e/2022-01-28-chain-of-thought/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2022-01-28"
date_precision: day
category: research
importance: 4
confidence: high
status: [Confirmed]
sources: 2
editor: human editor
human_review: null
version: "2026-10-04"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2022-01-28-chain-of-thought/

# Chain-of-thought prompting elicits reasoning in LLMs

Wei et al. showed that prompting large models to write out intermediate reasoning steps dramatically improves performance on math and logic tasks — an ability that emerges with scale.

## Key facts
- arXiv 2201.11903 (January 2022); NeurIPS 2022
- PaLM 540B with chain-of-thought reached state of the art on GSM8K math word problems at the time
- Follow-up: 'Let's think step by step' zero-shot CoT (Kojima et al., 2022)
- Precursor to trained reasoning models like OpenAI o1

## What happened

Adding worked examples with step-by-step reasoning in the prompt caused large models to reason explicitly before answering.

## Why it matters

Made 'thinking out loud' central to LLM capability; RL-trained reasoning models (o1, R1, Claude extended thinking) are its descendants.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): in its training data
- Claude Opus 5.5 (training cutoff June 2026): in its training data
- Gemini 4 Hydrogen (training cutoff March 2026): in its training data
- Grok 4.7 (training cutoff May 2026): in its training data

## Sources

1. [Chain-of-Thought Prompting Elicits Reasoning in Large Language Models (arXiv)](https://arxiv.org/abs/2201.11903) (arxiv.org, paper)
2. [Language Models Perform Reasoning via Chain of Thought (Google Research blog)](https://research.google/blog/language-models-perform-reasoning-via-chain-of-thought/) (research.google, official)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2024-09-12: [OpenAI o1: reasoning models trained with reinforcement learning](https://postcutoff.com/e/2024-09-12-openai-o1/index.md)