Pretraining Language Models for Diachronic Linguistic Change Discovery
Authors: name: Elisabeth Fittschen, name: Sabrina Li, name: Tom Lippincott, name: Leshem Choshen, name: Craig Messner

Large language models (LLMs) have shown potential as tools for scientific
discovery. This has engendered growing interest in their use in humanistic
disciplines, such as historical linguistics and literary studies. These fields
often construct arguments on the basis of delineations like genre, or more
inflexibly, time period. Although efforts have been made to restrict inference
to specific domains via fine-tuning or model editing, we posit that the only
true guarantee is domain-restricted pretraining -- typically, a data- and
compute-expensive proposition.
  We show that efficient pretraining techniques can produce useful models over
corpora too large for easy manual inspection but too small for "typical" LLM
approaches. We employ a novel date-attribution pipeline in order to obtain a
temporally-segmented dataset of five 10-million-word slices. We train two
corresponding five-model batteries over these corpus segments, efficient
pretraining and Llama3-8B parameter efficiently finetuned.
  We find that the pretrained models are faster to train than the finetuned
baselines and that they better respect the historical divisions of our corpus.
Emphasizing speed and precision over a-historical comprehensiveness enables a
number of novel approaches to hypothesis discovery and testing in our target
fields. Taking up diachronic linguistics as a testbed, we show that our method
enables the detection of a diverse set of phenomena, including en masse lexical
change, non-lexical (grammatical and morphological) change, and word sense
introduction/obsolescence. We provide a ready-to-use pipeline that allows
extension of our approach to other target fields with only minimal adaptation.