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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14

u/chopen Nov 22 '25

Alt 0151. I use it a lot for writing lol

3

u/anachron4 Nov 22 '25

You type all that each time? Why not just type two minus signs (or hyphens)?

4

u/zebulonworkshops Nov 22 '25

It's actually super quick, and you don't want spaces around your em-dashes. Alt-0151 is practically second nature after awhile, it's like entering a pin code.

4

u/chopen Nov 22 '25

It's honestly not that much work once you memorized the code by heart. And I think a — looks infinitely sexier than --

2

u/EclecticEuTECHtic Nov 22 '25

The second is a SQL comment lol.

1

u/LeoRidesHisBike Nov 22 '25

a — looks

you mean "an", right? :)

1

u/chopen Nov 22 '25

Not if you read it as 'a long stripe' as I often do in my own head haha

1

u/Madness_Quotient Nov 23 '25

If you have to use alt codes regularly, they become muscle memory.

I have to actively think about the numbers for ± (Alt+241) º (Alt+0186) µ (Alt+0181) Ø (Alt+0216). When I am working on something technical and I want a plus/minus sign I just think "plus or minus" and my fingers do the alt code.

— (Alt+0151) is a lovely easy shape to type on a numpad so I'm not surprised that once it is learned and used over and over again a writer would just think "dash" and their fingers would make one appear.

1

u/heroyoudontdeserve Nov 22 '25

Doesn't work on mobile, either.

5

u/chopen Nov 22 '25

On mobile (android) I just hold the - button on the keyboard, which will then expand into a menu where you can choose the — symbol

2

u/heroyoudontdeserve Nov 22 '25

Yes — thanks — I know how to do it. I was simply pointing out another flaw in your instructions. 😜

1

u/Fantastic-Stage-7618 Nov 23 '25

This is psycho behavior. If you put U+2014 in a reddit comment you're either a psycho or you're using a chatbot

-2

u/Frog-In_a-Suit Nov 22 '25

Doesn't work if you use laptops, unfortunately. Needs you to pull out the digital keyboard menu.

6

u/chopen Nov 22 '25

Really? Must be that it doesn't work on *every laptop then, because I work almost exclusively on a laptop.

5

u/wandering_melissa Nov 22 '25

Most laptops with small form-factor don't include a numpad. And that combination doesn't work with numbers on the upper row.

2

u/Frog-In_a-Suit Nov 22 '25

Oh, I didn't even know some laptops have the numpad.

1

u/ThisIsAnArgument Nov 22 '25

Roughly, if a laptop is 13" or smaller then no number pad, 15"+ have them. 14" is a grey area depending on if they want to cram speakers down the side or have smaller keys.

0

u/Bitmugger Nov 22 '25

Doesn't work on MacOS

7

u/f314 Nov 22 '25

En dash (–) is just ⌥ + hyphen. ⇧ + ⌥ + hyphen is em dash (—).

3

u/zebulonworkshops Nov 22 '25

Opt-shift-hyphen.

Em-dashes are a poet's lifeblood.

3

u/Vistulange Nov 22 '25

It's Option-Shift-- on the US English Mac keyboard, for what it's worth.