Small Models, Fewer Heads, More Forgetting: Sparse Attention Fine-Tuning for SLM Continual Learning

Hao Xu, Shezheng Song, Long Peng, Xiaodong Liu, Xiaopeng Li, Ma Jun, Shasha Li, Jie Yu


Abstract
Small Language Models (SLMs) have been widely deployed in edge computing and mobile devices. Generally, these models need to be continuously updated to adapt to dynamic environments and evolving user needs. Therefore, the performance of SLMs in continual learning has become a critical research focus. Compared to LLMs with rich redundant representation spaces, SLMs are more likely to overwrite previous representations during new task learning due to their fewer attention heads and layers. To address this issue, we propose LightLoRA, a sparse fine-tuning method specifically designed for SLMs. This method constructs a conflict-aware importance mechanism by combining raw importance from SVD decomposition with task conflict degrees based on gradient direction consistency. By selecting and updating heads that provide high contributions and low conflicts, LightLoRA successfully maintains sufficient space for knowledge preservation. Experimental results show that the proposed method reaches state-of-the-art performance across multiple benchmarks without adding extra parameters. Code is released on https://anonymous.4open.science/r/LightLoRA-077C.
Anthology ID:
2026.emnlp-main.1099
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
25205–25222
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URL:
https://aclanthology.org/2026.emnlp-main.1099/
DOI:
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Cite (ACL):
Hao Xu, Shezheng Song, Long Peng, Xiaodong Liu, Xiaopeng Li, Ma Jun, Shasha Li, and Jie Yu. 2026. Small Models, Fewer Heads, More Forgetting: Sparse Attention Fine-Tuning for SLM Continual Learning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 25205–25222, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Small Models, Fewer Heads, More Forgetting: Sparse Attention Fine-Tuning for SLM Continual Learning (Xu et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1099.pdf