Synthetic Pre-Pre-Training Improves Language Model Robustness to Noisy Pre-Training Data

Fuente: arXiv
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Autores principales: Guo, Xu, Peng, Runyu, Tong, Jian, Zhou, Yunhua, Lv, Haijun, Lu, Zhihui, Guo, Qipeng
Formato: Preprint
Publicado: 2026
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author Guo, Xu
Peng, Runyu
Tong, Jian
Zhou, Yunhua
Lv, Haijun
Lu, Zhihui
Guo, Qipeng
author_facet Guo, Xu
Peng, Runyu
Tong, Jian
Zhou, Yunhua
Lv, Haijun
Lu, Zhihui
Guo, Qipeng
contents Large language models (LLMs) rely on web-scale corpora for pre-training. The noise inherent in these datasets tends to obscure meaningful patterns and ultimately degrade model performance. Data curation mitigates but cannot eliminate such noise, so pre-training corpora remain noisy in practice. We therefore study whether a lightweight pre-pre-training (PPT) stage based on synthetic data with learnable temporal structure helps resist noisy data during the pre-training (PT) stage. Across various corruption settings, our method consistently improves robustness to noise during PT, with larger relative gains at higher noise levels. For a 1B-parameter model, a synthetic PPT stage with only 65M tokens achieves the same final loss as the baseline while using up to 49\% fewer natural-text PT tokens across different noise levels. Mechanistic analyses suggest PPT does not immediately suppress attention to noisy tokens. Rather, PPT-initialized models gradually downweight attention between corrupted tokens during noisy PT. This indicates that synthetic PPT inhibits noise self-modeling and shapes the subsequent optimization trajectory. Code is available at https://github.com/guox18/formal-language-prepretraining.
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id arxiv_https___arxiv_org_abs_2605_10129
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Synthetic Pre-Pre-Training Improves Language Model Robustness to Noisy Pre-Training Data
Guo, Xu
Peng, Runyu
Tong, Jian
Zhou, Yunhua
Lv, Haijun
Lu, Zhihui
Guo, Qipeng
Computation and Language
Large language models (LLMs) rely on web-scale corpora for pre-training. The noise inherent in these datasets tends to obscure meaningful patterns and ultimately degrade model performance. Data curation mitigates but cannot eliminate such noise, so pre-training corpora remain noisy in practice. We therefore study whether a lightweight pre-pre-training (PPT) stage based on synthetic data with learnable temporal structure helps resist noisy data during the pre-training (PT) stage. Across various corruption settings, our method consistently improves robustness to noise during PT, with larger relative gains at higher noise levels. For a 1B-parameter model, a synthetic PPT stage with only 65M tokens achieves the same final loss as the baseline while using up to 49\% fewer natural-text PT tokens across different noise levels. Mechanistic analyses suggest PPT does not immediately suppress attention to noisy tokens. Rather, PPT-initialized models gradually downweight attention between corrupted tokens during noisy PT. This indicates that synthetic PPT inhibits noise self-modeling and shapes the subsequent optimization trajectory. Code is available at https://github.com/guox18/formal-language-prepretraining.
title Synthetic Pre-Pre-Training Improves Language Model Robustness to Noisy Pre-Training Data
topic Computation and Language
url https://arxiv.org/abs/2605.10129