[_AzMoo]

Which is exactly why LLMs use these techniques so often. They're very common.

[kragen]

Well, em dashes are not all that common in text that people have written on computers, because em dashes were left out of ASCII. They're common in high-quality text like Wikipedia, academic papers, and published books.

My guess is that comma-separated lists tend to be a feature of text that is attempting to be either comprehensively expository—listing all the possibilities, all the relevant factors, etc.—or persuasive—listing a compelling set of examples or other supporting arguments so that at least one of them is likely to convince the reader.

[danielhughes]

I was surprised to learn from your comment that em dashes were left out of ASCII, because I thought I've been using them extensively in my writing. Perhaps I'm just relying heavily on the hyphen key. I mention that because it's likely instances of true em dash use (e.g. in the high-quality text you cite) and hyphen usage by people like me are close enough together in a vector space that the general pattern of a little horizontal line in the middle of a sentence is perceived as a common writing style by the LLMs.

I find myself constantly editing my natural writing style to sound less like an AI so this discussion of em dash use is a sore spot. Personally I think many people overrate their ability to recognize AI-generated copy without a good feedback loop of their own false positives (or false negatives for that matter).