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home / papers / 2026 / DAMASHA: Detecting AI in Mixed Adversarial Texts via Segmentation with Human-interpretable Attribution

DAMASHA: Detecting AI in Mixed Adversarial Texts via Segmentation with Human-interpretable Attribution

Paper · 2026 · L. D. M. S. Sai Teja, N. Siva Gopala Krishna, Ufaq Khan et al.

Summary

The paper addresses mixed-authorship segmentation: locating the points in a text where writing switches between a human and an AI model. It focuses on texts that have been deliberately perturbed to evade detectors. The authors observe that earlier work handled either boundary detection on clean mixed texts or adversarial robustness for whole-document classification, but never both together.

They release MAS, a benchmark that merges the TriBERT and M4GT mixed-text corpora with newly generated material. Every text in the combined corpus is then copied under several character- and punctuation-level attacks.

Their model, Info-Mask, adds a soft attribution mask that reweights token representations using stylometric and perplexity-based cues. The mask also provides Human-Interpretable Attribution (HIA) overlays that let reviewers see why a span was flagged.

The best variant, RMC*, reaches modest strict span-level scores. Most of its errors, however, miss the boundary by only a few tokens. In a human study, the overlays made annotators' decisions faster. The method currently supports only English.

Key points

  • MAS size and sources:
    • 95,859 base texts, multiplied by 7 versions (original plus attacked copies), for 671,013 rows in total.
    • Of the base texts, 46,830 are newly generated with GPT-4o, GPT-4.1, GPT-4.1-mini and DeepSeek-V3.
    • Domains are Reddit, News, Wikipedia, ArXiv and Q&A.
    • Released on Hugging Face as saiteja33/DAMASHA.
  • Attacks and data formats:
    • Listed attacks are misspelling, character substitution, invisible characters, punctuation substitution and upper/lower case swaps.
    • Texts come in Human→AI, AI→Human and sentence-level "Mix" formats, with boundaries annotated at the word level.
  • New metrics: Segment-wise Boundary Detection Accuracy (SBDA) and Segment Precision. Both are computed with IoU span matching at thresholds τ ∈ {0.3, 0.5, 0.7, 0.9}.
  • Main results for RMC with all features:*
    • Strict scores are SBDA 0.45 and SegPre 0.41.
    • Relaxed span accuracy at IoU ≥ 0.5 rises to 0.82.
    • 46% of boundary errors are off by just one token.
  • Interpretability checks:
    • Faithfulness test: masking the top-10% mask-weighted tokens drops SBDA@0.3 from 0.47 to 0.33.
    • Human study: covered 500 samples rated by 2 annotators (κ = 0.68).
    • Effect of overlays: decision time fell from 21.4 s to 8.7 s, and usefulness was rated 4.3 out of 5.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as L. D. M. S. Sai Teja, N. Siva Gopala Krishna, Ufaq Khan, Muhammad Haris Khan and Atul Mishra. 2026. DAMASHA: Detecting AI in Mixed Adversarial Texts via Segmentation with Human-interpretable Attribution. Findings of the Association for Computational Linguistics: EACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-eacl.326

@inproceedings{teja2026damasha,
  title = {{DAMASHA: Detecting AI in Mixed Adversarial Texts via Segmentation with Human-interpretable Attribution}},
  author = {L. D. M. S. Sai Teja, N. Siva Gopala Krishna, Ufaq Khan, Muhammad Haris Khan and Atul Mishra},
  booktitle = {Findings of the Association for Computational Linguistics: EACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-eacl.326},
  url = {https://doi.org/10.18653/v1/2026.findings-eacl.326}
}

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