CMU Flame Center Seminar - Jacob Springer April 11, 2025 12:30pm — 2:00pm Location: In Person and VIrtual - ET - Tepper Building 1403 and Zoom Speaker: JACOB SPRING , Ph.D. Student, Machine Learning Department, Carnegie Mellon University https://sprin.xyz/ Overtrained Language Models Are Harder to Fine-Tune Large language models are pre-trained on ever-growing token budgets under the assumption that better pre-training performance translates to improved downstream models. In this work, we challenge this assumption and show that extended pre-training can make models harder to fine-tune, leading to degraded final performance. We term this phenomenon catastrophic overtraining. For example, the instruction-tuned OLMo-1B model pre-trained on 3T tokens leads to over 2% worse performance on multiple standard LLM benchmarks than its 2.3T token counterpart. Through controlled experiments and theoretical analysis, we show that catastrophic overtraining arises from a systematic increase in the broad sensitivity of pre-trained parameters to modifications, including but not limited to fine-tuning. Our findings call for a critical reassessment of pre-training design that considers the downstream adaptability of the model. Paper Reference — Jacob Springer is a third-year PhD student in the Machine Learning Department at CMU, advised by Aditi Raghunathan. His research broadly focuses on the science of foundation models, emphasizing pre-training, fine-tuning, and optimization. His current research investigates factors affecting the adaptability of language models to new tasks—through fine-tuning or prompting—across all stages of the model lifecycle, from pre-training to inference. In Person and Zoom Participation. See announcement. Event Website: https://www.cmu.edu/flame/events/index.html Add event to Google Add event to iCal