The Three Patterns That Get Human Writing Flagged as AI
Detectors don't read your mind or check a blacklist of words — they measure rhythm and predictability. Here's what actually trips the alarm, and a real before/after rewrite that fixes it.
It's Not About Which Words You Used
A writer sends me a paragraph and asks what's wrong with it. Nothing is wrong with it, grammatically. Every sentence is correct. That's actually the problem — correctness with no variation is exactly what a detector is trained to notice.
Detectors don't know what AI is. They know what predictable text looks like, statistically, and they score how closely your sentences match that pattern. Three measurements do almost all the work: how predictable your word choices are, how uniform your sentence lengths are, and whether your paragraph argues or just lists.
Fix those three things and the flag usually drops, regardless of whether a model helped you draft the piece.
The Three Signals, Plainly
- Perplexity — how surprising your word choices are to a language model. Generic phrasing scores low (predictable); specific, opinionated phrasing scores higher (surprising).
- Burstiness — how much your sentence lengths swing. Human writing lurches: a long sentence, then a fragment, then a question. Model output tends to settle into a comfortable average and stay there.
- Logical flow — whether one sentence earns the next one, or whether the paragraph is a stack of true-but-disconnected facts that could be reordered without losing anything.
None of this means detectors are scanning for banned words like "delve" or "moreover." Those words correlate with low perplexity because they're statistically common filler, but swapping them for synonyms doesn't touch the underlying pattern. The sentence structure is still predictable — you've just changed its clothes.
One Paragraph, Rewritten
| Flagged Version | Rewritten Version |
|---|---|
| Remote work offers many benefits for employees. It provides flexibility in scheduling. It also reduces commuting time. Additionally, it can improve work-life balance. Many companies have adopted remote work policies as a result. | Cut the commute and something shifts. My neighbor used to lose ninety minutes a day to traffic; now she spends that time on a run before her first meeting. That's the real sell behind remote work — not "flexibility" as an abstraction, but hours you get back and get to spend on purpose. |
| Uniform sentence length, subject-verb-object every time, no sentence under eight words. | Lengths swing from four words to thirty. A fragment lands where a fragment should. |
| Four separate claims, no connective tissue — could be shuffled with no loss of meaning. | One example carries the argument; each sentence depends on the one before it. |
How to Actually Rewrite a Flagged Paragraph
- 1Find the most generic sentence first
Usually it's the topic sentence. Read it out loud — if it could open a paragraph about literally any product or policy, it's the low-perplexity one. Replace it with a concrete detail, a number, or a specific scene.
- 2Break the sentence-length pattern on purpose
Count words per sentence in your paragraph. If they're all clustered within five words of each other, chop one in half and merge two others into a longer, winding one. Read for rhythm, not just correctness.
- 3Make each sentence answer the one before it
Cover the paragraph and reveal it one sentence at a time. If sentence three doesn't need sentence two to make sense, they're not actually connected — they're a list dressed up as an argument. Add the reasoning that links them, or cut one.
- 4Read it back at normal speaking speed
Not silently — out loud, at the pace you'd talk to a colleague. Places where you stumble or want to add "honestly" or "look" are where your natural voice is trying to interrupt the flat draft. Let it.
Specificity is not a style choice — it's the single biggest lever you have over how predictable your writing reads to a model.
What This Doesn't Fix
This won't help a paragraph that's factually thin. If you have nothing specific to say, no amount of sentence-length variation manufactures a detail out of thin air. The rewrite above works because the writer had a real neighbor and a real commute to draw on — go find yours before you touch the sentence structure.
It also won't make a bad argument good. Burstiness and perplexity are surface measurements. A paragraph can vary its rhythm beautifully and still say nothing. Fix the thinking first, then fix the sound of it.
AI Humanizer Lab's free AI Humanizer is built around exactly these three signals — it varies sentence rhythm, swaps generic phrasing for specific language, and tightens the logical links between sentences, without changing what you're actually trying to say. Worth a pass on any paragraph that keeps coming back flagged.
Make your writing sound human
Humanize AI-generated text in one click with AI Humanizer Lab.
Try for free