Study Finds ChatGPT Is Influencing How People Write

Researchers led by data scientist Samuel Bestvater identified that the use of em dashes has doubled, as have the frequencies of words such as "delve," "testament" and "interplay." The study also recorded nearly triple the use of "negative parallelisms" — constructions like "it's not X, it's Y" — and a 63 percent rise in Oxford commas.

The findings suggest that AI-generated text is not only more prevalent but may also be reshaping human writing habits. Bestvater said some people have told him they now avoid em dashes to make their writing less similar to AI output. "If human writers are adjusting their choices of words and phrases and punctuation to try to differentiate their writing from AI-generated text, then you would see a pattern that looks sort of like that in the chart," he said.

Roger Kreuz, a cognitive psychologist at the University of Memphis, offered a complementary explanation. People who spend a lot of time reading or listening to AI content may adopt its vocabulary themselves. "People are tending to more commonly use these low-frequency words in their speech because they're spending a lot of time listening to or reading AI-generated content," Kreuz said.

Although word popularity has always shifted with culture and technology, the study highlights a two-way dynamic: AI developers are working to make model output more humanlike while human writers appear to be moving away from patterns they associate with machines.