Revisiting Chain-of-Thought Prompting: Zero-shot Can Be Stronger than Few-shot

TL;DR

This paper investigates the effectiveness of Chain-of-Thought prompting in recent strong language models, finding that traditional and enhanced CoT exemplars do not improve reasoning performance compared to Zero-Shot CoT, and often serve only to align output formats.

Contribution

The study systematically evaluates CoT prompting on recent models, revealing its limited benefits and highlighting the need to re-examine the ICL paradigm for mathematical reasoning tasks.

Findings

Traditional CoT does not improve reasoning in recent models.

Enhanced CoT exemplars fail to boost reasoning performance.

Models tend to ignore exemplars and focus on instructions.

Abstract

In-Context Learning (ICL) is an essential emergent ability of Large Language Models (LLMs), and recent studies introduce Chain-of-Thought (CoT) to exemplars of ICL to enhance the reasoning capability, especially in mathematics tasks. However, given the continuous advancement of model capabilities, it remains unclear whether CoT exemplars still benefit recent, stronger models in such tasks. Through systematic experiments, we find that for recent strong models such as the Qwen2.5 series, adding traditional CoT exemplars does not improve reasoning performance compared to Zero-Shot CoT. Instead, their primary function is to align the output format with human expectations. We further investigate the effectiveness of enhanced CoT exemplars, constructed using answers from advanced models such as \texttt{Qwen2.5-Max} and \texttt{DeepSeek-R1}. Experimental results indicate that these enhanced exemplars still fail to improve the model's reasoning performance. Further analysis reveals that models tend to ignore the exemplars and focus primarily on the instructions, leading to no observable gain in reasoning ability. Overall, our findings highlight the limitations of the current ICL+CoT framework in mathematical reasoning, calling for a re-examination of the ICL paradigm and the definition of exemplars.