@inproceedings{yao-etal-2026-large,
title = "How Do Large Language Models Learn Concepts During Continual Pre-Training?",
author = "Yao, Barry Menglong and
Li, Sha and
Yao, Yunzhi and
Liu, Minqian and
Xia, Zaishuo and
Wang, Qifan and
Huang, Lifu",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.2437/",
pages = "55302--55325",
ISBN = "979-8-89176-459-0",
abstract = "Human beings primarily understand the world through concepts (e.g., dog), abstract mental representations that structure perception, reasoning, and learning. However, how large language models (LLMs) acquire, retain, and forget such concepts during continual pretraining remains poorly understood. In this work, we study how individual concepts are acquired and forgotten, as well as how multiple concepts interact through interference and synergy. We link these behavioral dynamics to LLMs' internal concept circuits, computational subgraphs associated with specific concepts, and incorporate graph metrics to characterize circuit topology. Our analysis reveals: (1) LLMs' concept circuits provide a non-trivial, consistent signal of concept learning and forgetting; (2) concept circuit topology evolves stage-wise, rising during concept acquisition, and transiently rising before declining during concept forgetting; (3) semantically similar concepts induce stronger interference than weakly related ones; (4) conceptual knowledge differs in their transferability, with some significantly facilitating the learning of others. Together, our findings provide a circuit-level view of concept learning dynamics and motivate concept-aware training strategies, such as Circuit-aware Experience Replay, which uses circuit topology to prioritize concepts vulnerable to forgetting"
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<abstract>Human beings primarily understand the world through concepts (e.g., dog), abstract mental representations that structure perception, reasoning, and learning. However, how large language models (LLMs) acquire, retain, and forget such concepts during continual pretraining remains poorly understood. In this work, we study how individual concepts are acquired and forgotten, as well as how multiple concepts interact through interference and synergy. We link these behavioral dynamics to LLMs’ internal concept circuits, computational subgraphs associated with specific concepts, and incorporate graph metrics to characterize circuit topology. Our analysis reveals: (1) LLMs’ concept circuits provide a non-trivial, consistent signal of concept learning and forgetting; (2) concept circuit topology evolves stage-wise, rising during concept acquisition, and transiently rising before declining during concept forgetting; (3) semantically similar concepts induce stronger interference than weakly related ones; (4) conceptual knowledge differs in their transferability, with some significantly facilitating the learning of others. Together, our findings provide a circuit-level view of concept learning dynamics and motivate concept-aware training strategies, such as Circuit-aware Experience Replay, which uses circuit topology to prioritize concepts vulnerable to forgetting</abstract>
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%0 Conference Proceedings
%T How Do Large Language Models Learn Concepts During Continual Pre-Training?
%A Yao, Barry Menglong
%A Li, Sha
%A Yao, Yunzhi
%A Liu, Minqian
%A Xia, Zaishuo
%A Wang, Qifan
%A Huang, Lifu
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F yao-etal-2026-large
%X Human beings primarily understand the world through concepts (e.g., dog), abstract mental representations that structure perception, reasoning, and learning. However, how large language models (LLMs) acquire, retain, and forget such concepts during continual pretraining remains poorly understood. In this work, we study how individual concepts are acquired and forgotten, as well as how multiple concepts interact through interference and synergy. We link these behavioral dynamics to LLMs’ internal concept circuits, computational subgraphs associated with specific concepts, and incorporate graph metrics to characterize circuit topology. Our analysis reveals: (1) LLMs’ concept circuits provide a non-trivial, consistent signal of concept learning and forgetting; (2) concept circuit topology evolves stage-wise, rising during concept acquisition, and transiently rising before declining during concept forgetting; (3) semantically similar concepts induce stronger interference than weakly related ones; (4) conceptual knowledge differs in their transferability, with some significantly facilitating the learning of others. Together, our findings provide a circuit-level view of concept learning dynamics and motivate concept-aware training strategies, such as Circuit-aware Experience Replay, which uses circuit topology to prioritize concepts vulnerable to forgetting
%U https://aclanthology.org/2026.emnlp-main.2437/
%P 55302-55325
Markdown (Informal)
[How Do Large Language Models Learn Concepts During Continual Pre-Training?](https://aclanthology.org/2026.emnlp-main.2437/) (Yao et al., EMNLP 2026)
ACL