Experts revealed clear signs that the essays were written by ChatGPT and not by students.
This comes after the rise of generative AI tools such as ChatGPT sparked concerns about cheating among students in the education sector.
Repetition of words, tautologies and paragraphs beginning with “but” are telltale characteristics, researchers said.
The writing style of artificial intelligence tools is “bland” and “journalistic,” according to a Cambridge University Press and Assessment study.
With the help of ChatGPT, researchers compared essays written by three first-year undergraduate students with 164 essays written by IGCSE students.
These essays were graded by examiners, who then interviewed undergraduate students and analyzed their essays.
Studies have shown that essays written using ChatGPT perform poorly in analysis and comparison techniques compared to essays written without ChatGPT.
However, the ChatGPT application essay performed strongly on information and reflection skills.
Researchers identified several key features of ChatGPT writing style, including use of Latin vocabulary, repetition of words or phrases and ideas, and pleonasms.
Essays written with the help of ChatGPT were more likely to use numbered lists with items and paragraphs beginning with discourse markers such as “but,” “furthermore,” and “total.”
The researchers said ChatGPT's default writing style “reflects the bland, neat, and objective style characteristic of typical journalistic writing found on the Internet.”
The report said: “Students found ChatGPT useful for gathering information quickly.
“But they felt that relying solely on this technology would produce essays of low academic quality.”
Jude Brady, senior research fellow at Cambridge University Press and Assessment, said: “Our findings provide insight into the growing area of generative AI and evaluation, which is still uncharted territory.
“Despite the small sample size, we are excited about these findings because they have the ability to inform the work of teachers and students.”
“We hope our research will help people identify when ChatGPT created their text,” she said.
“For students and the wider population, learning how to use and sense generative AI forms an increasingly important aspect of digital literacy.”