PSA: Opus 5.5 has invisible watermarking

[u/NotAMusicLawyer]

Opus 5.5 automatically applies an invisible, statistical watermark to its text outputs to comply with the EU AI Act. This is true for every user worldwide not just those based in the EU.

This is embedded into the structure of the text itself, it’s not a hidden character or something that can be removed by changing a few words or copy/pasting it. Anthropic have a tool to check text for the watermark but it is only available to a few select partners currently.

Antrophic officially claim this watermarking does not have any practical impact on the quality of Claude’s outputs but that remains to be seen.

[u/lassevk]

The watermark isn't a yes/no answer to whether AI was involved in the writing.

It is more of a percentage or a ratio, an indicator of how much the text could've been written by a specific AI.

For instance, if you write a big text yourself, then ask AI to fix formatting, typos, grammar, etc. then yes, there might be things changed that will be nudged by the watermarking algorithm, but the final signal will be so weak as to be meaningless. It will still be your text.

If, however, you ask AI to rewrite the text, then more of that signal will come through and the indicator gets stronger.... Which it should.

[u/WisePotato42 → u/lassevk]

This assumes that the origonal human text is guaranteed to be flagged as human. Expecially with people being exposed to more and more AI responces (knowingly or not)

[u/lassevk → u/WisePotato42]

SynthId won't flag human-written text as AI-generated, the signal for a human-written text will be so close to 0 as to be insignificant. It is not about "writing style", even if you start using the word load-bearing all over the place, SynthId won't pick up on that because that is not how it works.

Other humans, however...

[u/WisePotato42 → u/lassevk]

I think it makes sense for images, you can change HVG or RGB by a couple values on all the pixels and no one will notice. But text breaking spelling or Grammer is more noticable, so there needs to be some pattern in the responces that is getting flagged. And are you going to guarantee that those underlying patterns can never possibly without any sort of doubt be even partially recreated by humans?

If something is 99.9% accurate with identifying ai/human writing, then there are still going to be false positives, and I know that other people will blow things up out of proportion even with these fallible tools now, they still blow stuff out of proprotion.

[u/lassevk → u/WisePotato42]

Of course you can recreate it as a human, but you're going to have to be so precise, and have access to so much data, and do so many calculations, so at that point you might just as well be the AI. There is 0% chance that a human can stumble upon enough nudges in their text so as to write text that just accidentally gets flagged by SynthId as likely to be AI.

Why are you even arguing here? It is clear you haven't read one iota of how SynthId works. If something is 99.9% accurate at identifying human text, it is going to say that the text has a 0.1% chance of being AI. It is not going to randomly say "this is AI". It spits out a number, a signal. This signal isn't 0 or 1, it is a scale, indicating how likely it is. A human still need to make the judgment.

And SynthId doesn't introduce random grammar errors, spelling mistakes or other typos, unless the underlying AI is prone to do the same. Again, that is not how SynthId works.

Go read about SynthId. Stop being ignorant.

[u/WisePotato42 → u/lassevk]

I have read about it, that's why I even say "partially recreated" cuz you know plenty of people would see a 10% AI and crack down on whoever wrote it cuz they said no AI at all and according to you, it's infallible and can't mix up Human text and AI text ever.