AI models can identify authors of online text, threatening anonymity for people with published writing

Claude Opus 4.7 successfully identified tech writer Kelsey Piper as the author of unpublished 150-word writing samples each time it was tested; Semafor's Tom Chivers replicated the finding with a segment of his 2019 book.

Other AI models were less successful than Claude, and Claude could not identify people who lacked published real-name writing — though that limitation may change.

Anonymity may become difficult to maintain: someone posting a detailed anonymous review on a platform like Glassdoor could have the text identified by AI, revealing their identity to companies.