Why does AI writing sound robotic, and what patterns give it away?

Where the flatness comes from

A model is trained to continue text plausibly. Plausible means average: the safe phrase, the familiar structure, the claim nobody could argue with. A person writing from experience takes small risks. They name the odd detail, change pace, leave a thought short.

Researchers have measured one side of this. A study of more than 15 million biomedical abstracts found that the arrival of large language models produced "an abrupt increase in the frequency of certain style words", and the authors used that excess vocabulary to estimate how widely the tools were being used (Kobak et al., arXiv 2406.07016). The takeaway for an editor is modest: a tool's favourite words become visible when they pile up. One such word proves nothing. A page full of them reads as filler.

Seven patterns to look for

Pattern	What it looks like	What to do
Even rhythm	Four or five sentences of nearly the same length	Join two, cut one short, let one run long
Stock openers	"It is important to note that", "In today's world"	Delete and start with the point
Hedging	"can often help", "may potentially"	Say what you know, or say you do not know
Triplets	"clear, concise and compelling"	Keep the one word that is true
Empty transitions	"Moreover", "Furthermore" at every paragraph start	Keep only where the logic needs a signpost
Abstract nouns	"the implementation of strategies"	Name the thing and the action
Summary ending	A last paragraph that repeats the post	End on the last useful point

A before and after

Draft:

Moreover, effective communication is a crucial element in fostering strong relationships, and it can often help teams to navigate challenges in a meaningful way.

Edited:

Teams argue less when people say what they need. Ours stopped most arguments by writing the request in one sentence before the meeting.

The edit does three things. It uses a concrete claim, a short sentence beside a longer one, and no connector word. Purdue OWL's guidance on concision says the goal is to "use the most effective words", and that "words that don't accomplish enough should be fired" (Purdue OWL, Concision). Its examples show a wordy sentence of 14 words shrinking to 8 while conveying more.

How to find the patterns in your own draft

1. Read the draft aloud and mark every sentence that sounds like a press release.
2. Underline the first three words of each paragraph. If they match, vary them.
3. Count the lists of three. Keep the ones that are true, and trim the rest to one item.
4. Search for "moreover", "furthermore", "it is important" and "plays a crucial role". Delete most hits.
5. Replace one abstract sentence per paragraph with an example from your own work.

For the full editing routine, see how to edit an AI-generated draft.

What these patterns are not

They are not a test of who wrote the text. Human writers use stock phrases too, especially in formal reports and in a second language. Do not treat a checklist of patterns as evidence against another person, and do not trust any tool's verdict on your own writing without reading the text yourself. Edit for clarity. If a school, journal or employer asks you to state AI use, state it.