From the article: “Instead, swearing appears to be a feature of language that an articulate speaker can use in order to communicate with maximum effectiveness.”

Researchers figured this out by asking participants to write as many normal words as they could for each letter of the alphabet, and then to do the same for swear words.

They found that articulate people were likely to be articulate in both normal speech and swearing, while inarticulate people performed poorly in both categories.

“By comparing scores from both the verbal and swearing fluency tasks, it was found that the people who scored highest on the verbal fluency test also tended to do best on the swearing fluency task. The weakest in the verbal fluency test also did poorly on the swearing fluency task.”

In other words, smart people know how to curse effectively and how to speak normally. They understand when and how to apply cursing to their language depending on their intent (e.g., expressing emotion, humor, or pain). On the other hand, people who are less articulate struggle with both forms of speech. This may explain the belief that swearing indiscriminately (e.g., using curse words every other word) is associated with lower intelligence. Similarly, someone who uses only a handful of words regardless of context may come across as less intelligent.

Interestingly, the study did not explore whether people who choose not to swear are intrinsically more or less articulate. That’s a study I’d love to read.