One-shot Style Transfer LLM log-probabilities for Authorship Attribution and Verification

Pablo Miralles-González, Javier Huertas-Tato, Alejandro Martín, David Camacho


Abstract
Computational stylometry studies writing style through quantitative textual patterns, enabling applications such as authorship attribution, identity linking, and plagiarism detection. Despite the relevance of language modeling to these tasks, the pre-training of modern large language models (LLMs) has been underutilized in authorship attribution and verification. We introduce an unsupervised framework that uses the log-probabilities of an LLM to measure style transferability between two texts. This framework takes advantage of the extensive Causal Language Modeling (CLM) pre-training, one-shot capabilities and scale of LLMs, avoiding explicit supervision. Our methods substantially outperform prompting-based unsupervised baselines in authorship verification at similar model sizes, and is competitive with or improves contrastive baselines in most settings with sufficient model scale. We further observe strong performance across non-English languages. The effectiveness of the proposed framework improves consistently with increasing model scale. In the case of authorship verification, we propose an additional mechanism that increases test-time computation to improve accuracy; enabling flexible trade-offs between computational cost and task performance.
Anthology ID:
2026.findings-emnlp.14
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:
278–297
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.14/
DOI:
Bibkey:
Cite (ACL):
Pablo Miralles-González, Javier Huertas-Tato, Alejandro Martín, and David Camacho. 2026. One-shot Style Transfer LLM log-probabilities for Authorship Attribution and Verification. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 278–297, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
One-shot Style Transfer LLM log-probabilities for Authorship Attribution and Verification (Miralles-González et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.14.pdf