Characterizing Narrative Content in Web-scale LLM Pretraining Data

Teagan Johnson, Elliott Ash, Andrew Piper, Maria Antoniak


Abstract
The narrative composition of web-scale LLM pretraining corpora remains largely unexplored, even though narrative is a fundamental mode of human communication. We present the first fine-grained study of narrative features in Dolma, a 3-trillion-token open pretraining corpus. Drawing on narrative theory, we design a framework spanning three core narrative elements (agency, setting, and events) operationalized as 11 interpretable dimensions. After curating and hand-annotating a diverse set of 400 passages, we create an LLM-labeled dataset of 25K passages, and finally, we finetune and validate NarraBERT, two RoBERTa-based models for fine-grained narrative prediction. We apply NarraBERT to ∼13M passages, resulting in a new dataset, NarraDolma. We find that narrative structure is measurable at scale across extremely heterogeneous data and narrative qualities are unequally distributed across pretraining sources, topics, and formats in ways that current data curation practices neither measure nor account for. Our framework, dataset, and analyses provide a foundation for understanding how narrative qualities are distributed in LLM pretraining data.
Anthology ID:
2026.findings-emnlp.2259
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
48364–48404
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2259/
DOI:
10.18653/2026.findings-emnlp.2259
Bibkey:
Cite (ACL):
Teagan Johnson, Elliott Ash, Andrew Piper, and Maria Antoniak. 2026. Characterizing Narrative Content in Web-scale LLM Pretraining Data. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 48364–48404, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Characterizing Narrative Content in Web-scale LLM Pretraining Data (Johnson et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2259.pdf