The most common reasons human writing gets flagged
Formal templates. Lab reports, literature reviews and five-paragraph essays follow fixed structures with predictable phrasing. Detectors read that as low perplexity.
Grammar and rewriting tools. Running every sentence through Grammarly or a similar tool smooths out the quirks that make writing look human. Some of these tools now use AI to rewrite whole sentences.
A limited vocabulary. If you write in a second language, you probably rely on common words and safe sentence patterns. That is exactly what detectors associate with AI.
Over-polishing. Editing a piece many times can strip out every tangent and short sentence, leaving something very even.
AI detector false positives for non-native speakers
In 2023, Stanford researchers ran 91 TOEFL essays written by non-native English speakers through seven popular detectors. More than half were labelled AI-generated, an average false-positive rate of 61%. The same detectors were close to perfect on essays by US eighth graders.
A 2026 preprint looked at more than 135,000 manuscripts before and after professional English editing and found that editing style alone could push AI scores up or down, depending on the detector.
Try it on your own text
Paste a paragraph and see your AI score before and after.
Both scores on one card, before you copy.
Download on the App StoreHow to lower a false AI score on your own writing
Add specific details: names, dates, numbers, places and your own reasoning. Vary sentence length on purpose. Cut stock transitions like "furthermore" and "in conclusion".
Check before you submit. Paste your text into TextHumanizer and tap Check for AI to see which parts score high. Rewrite those sections in your own voice, then check again.
Keep evidence as you go. Write in a document with version history, and keep your notes. If you are ever questioned, a clear record of your process is the best defence.
Questions
Can Grammarly make my writing look like AI?
It can. Heavy use of grammar and rewriting suggestions makes sentences more uniform, and AI-powered rewrite features can introduce the same patterns detectors look for.
Why does my essay score differently on different detectors?
Each detector uses its own model and training data, so the same text can score 10% on one and 80% on another. That inconsistency is one reason scores should not be treated as proof.