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Detecting LLM-Generated Texts with “Classical” Machine Learning

38 points59 minutesblog.lyc8503.net
akersten23 minutes ago

Text is simply not information dense enough to be able to decode some arbitrary signal of provenance from it. Sure you might be able to detect today's tells (particular sentence structures preferred by Claude, phrases, etc) to get you some arbitrary chance percentage it was machine generated, but it's a bad fiction to perpetuate that any of this is anything more than tarot card reading.

Images, absolutely, there are tell-tale artifacts from today's generators that simply aren't emitted by "natural" paths to create them, and you can "detect AI" with high confidence (for now). Words, no, the signal is far too sparse and we are well into undetectable sophistication with today's models, let alone tomorrow's.

stymaar10 minutes ago

> but it's a bad fiction to perpetuate that any of this is anything more than tarot card reading.

Hard disagree. LLMs (especially base ones, that only received pre-training) can produce output that is undistinguishable from human writing (because that's what they were trained to do).

But commercial chat models are specifically tuned in a way that maximizes user engagement. It's that specific tuning that is very easy to spot when reading AI slop, and that's not surprising that it's easy to spot automatically either. And I don't think that's going to change anytime soon, unless their incentives change.

(We can say exactly the same thing about man-made stuff optimized for a specific purpose, like stock photography, clickbait titles or industrial food: they aren't stereotypical because their creator lacks the skill to make them otherwise, they are like that because that's what works best).

empath757 minutes ago

It does mean that this will have a drift problem if it's just trained on the idiosyncrasies of model fine tuning. That's fine! But it is something to be aware of.

jgalt21216 minutes ago

It depends on how much text. For example, chardet often falls down on short strings, but 1K characters it nails it.

Krssst35 minutes ago

The classifier does not seem so big, I wonder if something like it for English could be used in a browser extension to run against every single paragraph being displayed ?

If the internet is going to drown in LLM text it would be nice to have tools to detect that automatically just like we have adblockers today to avoid wasting time on ads.

(the article was a good read, thanks!)

xiaoyu200631 minutes ago

I assume different models will have different distribution, so it has to be kept updated?

Krssst24 minutes ago

The article mentions that AI texts are often caught by multiple models, so hopefully text from newer LLMs could still be caught without updating the model?

teeray9 minutes ago

The problems are simply too great if an LLM detector has any false positives at all. Imagine how soul-crushing writing an entire dissertation by hand and having it rejected because some “good enough” LLM detector decides you write too much like an AI.

aberoham26 minutes ago

I wonder about this technique vs simple SVM classifiers: https://x.com/rosmine/status/2056406399471558872?s=20

unfocso43 minutes ago

I had done the same for classifying and generating bookmarks of thousands of datasheets, along with a very naive yolo-based classificator (to detect pages made out of diagrams and pictures mostly).

Done with GLM-OCR, I had to watch text sloooowly crawl out of the llm and still have to live with hallucinations and the model not following the schema

XiphiasX18 minutes ago

Anything too “clever” and “snappy” = instaLLM

cyanydeez46 minutes ago

today, sure.

Tomorrow, the LLMs will be training the humans thought patterns that will directly start skewing their natural writing.

Generation alpha is going to have a lot of trouble if we keep perpetuating the myth that you can really interpret text in an ongoing fashion.