arXiv AI By Chang Su, Bin Wu, Emine Yilmaz, Yao Lu

What Improves During Pretraining? Tracking Knowledge Acquisition with Point-in-Time Models

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The paper investigates how language models acquire knowledge over the course of pretraining by using point-in-time models trained on web snapshots from different years. It introduces a temporal variability score (TVS) that measures how consistently a knowledge item is represented across these snapshots. The study finds that items with high TVS improve more rapidly later in training and outperform low‑TVS items in most benchmark settings, especially on knowledge‑intensive tasks.

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