Hidden structure

Rip out trigger words and em dashes and detectors can still spot AI writing 93% of the time. AI’s tells are hidden in the structure. Here are six structural markers of AI writing, and how to avoid them.

Researchers at U of Maryland scored 61,608 stories to find what separates human writing from AI. When they fine-tuned a new model to fake human style, detection fell from 97% to 3%. But when they threw out “style” and judged the writing on how a story was built, the machine still got caught. 

Six rules from the data:

Don't state the moral.

AI explains its own theme 77% of the time.

Humans do it 52% of them.

No spoon feeding.

Name names.

AI hides behind "a recent study."

Humans cite actual sources at twice the rate.

Specificity reads as human.

Don't tie all the bows.

When writing fiction, AI resolves plot threads and side arguments 47% of the time.

Humans only resolve 27% of threads. Leave them loose. 

Vary the build.

Flat, even escalation is the strongest machine tell.

Let some passages run long and others land short.

Say the feeling.

AI turns emotion into body parts 81% of the time.

Too many tight chests and cold sweats.

Sometimes "afraid" is enough.

Write like someone's reading.

AI writes as if the room is empty.

Address the reader as a partner — "we," not "you."

The fix isn’t a no-no list.

It’s brevity, specificity, ambiguity, variety, and solidarity.


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Source: StoryScope: Investigating idiosyncrasies in AI fiction, Russell et al, Apr 2026