If a human-vs-machine detector's threshold is set for a 5% false-positive rate, does that rate hold on a kind of text it never saw?
research/mimic-threshold
If a detector's threshold is set for a 5% false-positive rate, does it hold on an unseen text type? Leave-one-family-out with the mimic-contexts n-gram detector: realised rate 0.00 to 0.54 (abstracts 0.54, books 0.18), and recipes catch 1.7% of machine text. Preliminary, plain-prompt RAID text only.
What it found
The mimic-contexts n-gram detector is fit on seven RAID families and its threshold set so 5% of human text is flagged (out-of-fold), then applied to the eighth. Realised false-positive rates run from 0.00 to 0.54: abstracts 0.54, books 0.18, while news, poetry, recipes, reddit, reviews and wiki sit at 0.00–0.06. On recipes the cut-off is too strict instead: it catches 1.7% of machine text where a threshold set on recipes would catch 46%. AUROC does not show this (books has the best, 0.993, and the second-worst rate). Preliminary: plain-prompt RAID text, one detector type, one split, no LLM run.
A figure from its own output
Paper, code and results
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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.