@inproceedings{crosbie-shutova-2025-induction,
title = "Induction Heads as an Essential Mechanism for Pattern Matching in In-context Learning",
author = "Crosbie, Joy and
Shutova, Ekaterina",
editor = "Chiruzzo, Luis and
Ritter, Alan and
Wang, Lu",
booktitle = "Findings of the Association for Computational Linguistics: NAACL 2025",
month = apr,
year = "2025",
address = "Albuquerque, New Mexico",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2025.findings-naacl.283/",
doi = "10.18653/v1/2025.findings-naacl.283",
pages = "5034--5096",
ISBN = "979-8-89176-195-7",
abstract = "Large language models (LLMs) have shown a remarkable ability to learn and perform complex tasks through in-context learning (ICL). However, a comprehensive understanding of its internal mechanisms is still lacking. This paper explores the role of induction heads in a few-shot ICL setting. We analyse two state-of-the-art models, Llama-3-8B and InternLM2-20B on abstract pattern recognition and NLP tasks. Our results show that even a minimal ablation of induction heads leads to ICL performance decreases of up to {\textasciitilde}32{\%} for abstract pattern recognition tasks, bringing the performance close to random. For NLP tasks, this ablation substantially decreases the model{'}s ability to benefit from examples, bringing few-shot ICL performance close to that of zero-shot prompts. We further use attention knockout to disable specific induction patterns, and present fine-grained evidence for the role that the induction mechanism plays in ICL."
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<abstract>Large language models (LLMs) have shown a remarkable ability to learn and perform complex tasks through in-context learning (ICL). However, a comprehensive understanding of its internal mechanisms is still lacking. This paper explores the role of induction heads in a few-shot ICL setting. We analyse two state-of-the-art models, Llama-3-8B and InternLM2-20B on abstract pattern recognition and NLP tasks. Our results show that even a minimal ablation of induction heads leads to ICL performance decreases of up to ~32% for abstract pattern recognition tasks, bringing the performance close to random. For NLP tasks, this ablation substantially decreases the model’s ability to benefit from examples, bringing few-shot ICL performance close to that of zero-shot prompts. We further use attention knockout to disable specific induction patterns, and present fine-grained evidence for the role that the induction mechanism plays in ICL.</abstract>
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%0 Conference Proceedings
%T Induction Heads as an Essential Mechanism for Pattern Matching in In-context Learning
%A Crosbie, Joy
%A Shutova, Ekaterina
%Y Chiruzzo, Luis
%Y Ritter, Alan
%Y Wang, Lu
%S Findings of the Association for Computational Linguistics: NAACL 2025
%D 2025
%8 April
%I Association for Computational Linguistics
%C Albuquerque, New Mexico
%@ 979-8-89176-195-7
%F crosbie-shutova-2025-induction
%X Large language models (LLMs) have shown a remarkable ability to learn and perform complex tasks through in-context learning (ICL). However, a comprehensive understanding of its internal mechanisms is still lacking. This paper explores the role of induction heads in a few-shot ICL setting. We analyse two state-of-the-art models, Llama-3-8B and InternLM2-20B on abstract pattern recognition and NLP tasks. Our results show that even a minimal ablation of induction heads leads to ICL performance decreases of up to ~32% for abstract pattern recognition tasks, bringing the performance close to random. For NLP tasks, this ablation substantially decreases the model’s ability to benefit from examples, bringing few-shot ICL performance close to that of zero-shot prompts. We further use attention knockout to disable specific induction patterns, and present fine-grained evidence for the role that the induction mechanism plays in ICL.
%R 10.18653/v1/2025.findings-naacl.283
%U https://aclanthology.org/2025.findings-naacl.283/
%U https://doi.org/10.18653/v1/2025.findings-naacl.283
%P 5034-5096
Markdown (Informal)
[Induction Heads as an Essential Mechanism for Pattern Matching in In-context Learning](https://aclanthology.org/2025.findings-naacl.283/) (Crosbie & Shutova, Findings 2025)
ACL