"Delve" and ChatGPT: why one word rose in AI writing

Why does ChatGPT say "delve" so much?

Probably because of the last step in making a chatbot, which rewards the answers human raters prefer. A 2025 study found the rise of words like "delve" consistent with that step. Who the raters were may explain why this word got the push. Nobody has proved it yet.

Tom Juzek and Zina Ward's COLING 2025 paper asks this exact question in its title. They began by finding twenty-one words whose growth in scientific abstracts was likely down to people writing with language models, "delve" among them, and then went looking for the cause. They found no evidence that the model architecture, the training algorithms or the training data were responsible. Their comparisons between models were consistent with reinforcement learning from human feedback playing a role, the step where people rate a model's answers and it learns to give more of the ones they liked. Then the result got stranger: in an online study, participants seemed to respond to "delve" differently from the other twenty words. The authors are frank that a lack of transparency surrounding model development makes the question hard to settle, and we think they're right to stop short.

The scale is easy to see in the data. In 2022, "delves" turned up in 7.5 of every 100,000 PubMed abstracts. Two years later it was 357. Before rounding, the 2024 share is 47.8 times the 2022 share. The chart above has every form of the word, year by year.

Where "delve" is ordinary English

The raters are the other half of the story. In April 2024, the Guardian's Alex Hern reported that this feedback work takes hundreds of thousands of hours, and that AI companies outsource it to English-speaking workers in the global south because they are cheap to hire. He added that in Nigeria, "delve" is much more common in business English than in England or the US. If the people writing and rating the model's answers reached for the word, the model had every chance to learn it from them.

Whether or not that explanation holds up, one part of it isn't in doubt: for many Nigerian writers, "delve" is just a word they use. Hern saw where that leads: "If AI-ese sounds like African English, then African English sounds like AI-ese." A reader who treats "delve" as a giveaway ends up flagging Nigerian professionals for writing the way they always have, and that's a cost we don't want our tools to impose.

The tells "delve" trips

Slop or Not's checker catches "delve" with its vocabulary tell, ai-vocab, which marks every listed form of the word wherever it appears in your text. One phrase is handled differently. "As we delve into" belongs to the opening cliché tell, because what gives that sentence away is the throat-clearing opener rather than the single word inside it.

Neither tell hands down a verdict. People wrote "delves" in 2022 and they still write it, so the word on its own proves nothing; the chart describes a trend across a huge body of text, not where your sentence came from. If the checker marks "delve" in a draft, take it as a question about that draft, and look at what else it marks before you decide anything.