Building Auditable AI Text Detectors with Sparse Autoencoders

Liam Dugan, Callum Stuart McDougall, Matthew Denton, Philip Pham, Christine Kaeser-Chen, Chris Callison-Burch


Abstract
AI-generated text detectors are increasingly deployed in consequential settings—peer review, education, admissions, journalism, and content moderation—where their outputs directly affect individuals. Yet the strongest detectors are fine-tuned neural classifiers whose decisions are opaque, while transparent alternatives (stylometric and linguistic-feature classifiers) underperform them by wide margins. We present a pipeline that converts a fine-tuned neural detector into a classifier that operates on human-readable concepts. We accomplish this by training sparse autoencoders (SAEs) directly on a detector’s residual stream, assigning auto-interpretation labels to each SAE feature, and retaining only features whose generated descriptions pass a global fidelity threshold. We then train a lightweight classifier on just the interpretable features. We find that our SAEs recover latent concepts that correspond to highly specific and predictive linguistic “tells” of AI-generated text. Classifiers built on these extracted features are not only highly interpretable but exhibit stronger performance on out-of-distribution texts than either neural or stylometric alternatives.
Anthology ID:
2026.emnlp-main.762
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
17640–17689
Language:
URL:
https://aclanthology.org/2026.emnlp-main.762/
DOI:
Bibkey:
Cite (ACL):
Liam Dugan, Callum Stuart McDougall, Matthew Denton, Philip Pham, Christine Kaeser-Chen, and Chris Callison-Burch. 2026. Building Auditable AI Text Detectors with Sparse Autoencoders. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 17640–17689, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Building Auditable AI Text Detectors with Sparse Autoencoders (Dugan et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.762.pdf