Cobalynx

Questions from the bench

How do AI detectors work?

AI detectors analyze writing patterns that humans wouldn't notice, such as word predictability and sentence rhythm, then compare these patterns against large collections of writing where authorship is known. The detector provides an estimate of likelihood rather than definitive proof, and Cobalynx publishes its error rates so users can see how often the estimate was wrong.

What is a false positive and what is Cobalynx's rate?

A false positive occurs when a person wrote text but the software incorrectly identified it as machine-written. This is the most damaging type of error. Cobalynx's false-positive rate is 2.1% (14 of 670 texts), with a statistical upper bound of 3.5%, and the thresholds are set to keep confident wrong accusations as close to zero as possible.

Can Cobalynx prove a text is human?

No. No AI detection tool can prove a text was written by a human. Cobalynx provides an AI-likelihood score tested against real outcomes, showing how often texts scoring similarly turned out to come from AI. The tool never offers human-verified certification because that technology does not exist.

Do AI detectors discriminate against non-native English speakers?

Yes. Mainstream AI detection tools flag non-native writing far more often than they should. A 2023 Stanford study found that more than 60% of essays written by non-native speakers were flagged by seven popular tools. Cobalynx measured its own error rate on ESL writing and publishes it separately alongside other error metrics.

Can AI writing be detected after paraphrasing or “humanizers”?

Less well. Text that a person rewrote on purpose so it would slip past a detector is the hardest case there is, for every tool on the market and for ours as well, so we ran that case on purpose and put the result out with the rest. Our published results include a test split where the AI text had been run through a paraphraser first, and you can see how the detector did on it (the good and the bad) on the evidence page.