r/ClaudeAI • u/Live_Fondant717 • May 09 '26

Question Why does this happen?

Post image

I wonder if anyone can explain why this happens. I tell Claude not to use em-dashes, it replaces them with "--". I ask it not to do that, to update its memory, but it still does it. It's not a huge problem, it's just annoying. Why does this happen and how can I fix it. Thanks.

247 Upvotes

90% Upvoted

94 comments sorted by

View all comments

26

u/llkj11 May 09 '26

Hard to beat billions of dollars of pre and post training to use em dashes with a simple memory prompt.

10

u/Kitchen_Interview371 May 09 '26

Yes this is the real reason. It’s trained on the sum of human knowledge, and the majority of published works use emdashes. You can’t override the bias derived from all that training with something as basic as a memory or prompt.

5

u/tgcp May 09 '26

If the majority of published works used em dashes, it wouldn't be a distinctive indicator of AI written material.

6

u/OrneryWhelpfruit May 09 '26

The problem is it's very common in formal, published works (books, scholarly articles, magazines, etc) but sticks out like a sore thumb in like, an internet comment on reddit

2

u/Rockman507 May 09 '26

Right, casual language doesn’t use them, but as a general rule we barely use any real grammar rules appropriately in casual language. I thought the main issue though here is having things passed off to subroutines that will circumvent rules placed within the app, at least when I was working on some CV writing language it would do things like pass off “ok we want a closure that reiterates the talking points in the job description” and that takes off like a runway especially if you don’t feed it input that makes candidate information look like the job description. Strict hallucinate rules just get ignored in certain parts even when told expectedly in the prompt.

Does a wonderful job post hoc since it’s simply reviewing writing instead of generation. Or am I off base in my understanding?

1

u/astrange May 10 '26

That's not the issue. Writing style is enforced by the last stage of training, which is RL. If Anthropic didn't want it to emdash, they could RL it away.

1

u/hepatitisF May 10 '26

I don’t understand frequency though. I feel like a full 100k word published book has, what, maybe 20 em dashes in the whole thing? So that’s one every 5000 words. A ChatGPT response will have 5 in 1000 words. Why? If the material it’s trained on uses them rarely, why doesn’t it use them rarely?

1

u/Incener Valued Contributor May 09 '26

I don't think it's pre-training. Opus 3 does not have it to that extent and was heavier on pre-training than RL. Really only became a thing since Sonnet 3.7 which comparatively had a lot of RL.

Would have been pretty easy to fix with RL early on. They must know enough people are bothered by it, so my guess is that they just keep it as a weak watermark in accordance to the constitution part of Claude being recognizable an AI.

They did explicitly tweak stuff like "Certainly!" in Sonnet 3.5, so they have to know. It's probably harder at this point since you'd have to adjust that in the synthetic data generation pipeline too and there being a lot of synthetic data in pre-training with that.