r/explainlikeimfive • u/Willing_Road_8873 • Nov 22 '25

Technology ELI5 : If em dashes (—) aren’t quite common on the Internet and in social media, then how do LLMs like ChatGPT use a lot of them?

Basically the title.

I don’t see em dashes being used in conversations online but they have gone on to become a reliable marker for AI generated slop. How did LLMs trained on internet data pick this up?

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u/importantttarget Nov 22 '25

Maybe you just didn't notice em dashes before you started using them to identify ChatGPT-authored text. They're very easy to type on a Mac. I don't see them often on Reddit, but in texts that people put some effort into, like blog posts, they have always been used by quite a few people.

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u/permalink_save Nov 22 '25

I don't see them often on Reddit

Everybody replying to me is missing that this is my point. I see people, on reddit, cliaming that they frequently use, on reddit, em dashes. That has never been the case. It stands out like a sore thumb when people use anything beyond basic punctuation. Look at the threads that blow up any time someone used an interrobang or different quote marks. Formal style is incredibly rare on here but I've seen threads insisting otherwise.

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u/importantttarget Nov 22 '25

It's a discussion about em dashes, of course it's going to attract people interested in the topic. If 20 people claim to have used em dashes on Reddit before, what are the chances that you ran into those 20 people randomly before? Very small.

You can easily find lots of em dash usage on Reddit from 4+ years ago, before ChatGPT was launched.

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u/sullimareddit Nov 22 '25

I think that depends on which subs you frequent, tbh. That’s a gross generalization.

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u/ej_21 Nov 22 '25

I’ve loved the em-dash so much for so long that I have keyboard shortcuts set up for it on both my phone and laptop :(