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“Language models seem to be much better than humans at next-token prediction” by Buck, Fabien and LawrenceC

LessWrong (Curated)

Audio version of the posts shared in the LessWrong Curated newsletter.




Crossposted from the  AI Alignment Forum. May contain more technical jargon than usual.

[Thanks to a variety of people for comments and assistance (especially Paul Christiano, Nostalgebraist, and Rafe Kennedy), and to various people for playing the game. Buck wrote the top-1 prediction web app; Fabien wrote the code for the perplexity experiment and did most of the analysis and wrote up the math here, Lawrence did the research on previous measurements. Epistemic status: we're pretty confident of our work here, but haven't engaged in a super thorough review process of all of it--this was more like a side-project than a core research project.]

How good are modern language models compared to humans, at the task language models are trained on (next token prediction on internet text)? While there are language-based tasks that you can construct where humans can make a next-token prediction better than any language model, we aren't aware of any apples-to-apples comparisons on non-handcrafted datasets. To answer this question, we performed a few experiments comparing humans to language models on next-token prediction on OpenWebText.

Contrary to some previous claims, we found that humans seem to be consistently worse at next-token prediction (in terms of both top-1 accuracy and perplexity) than even small models like Fairseq-125M, a 12-layer transformer roughly the size and quality of GPT-1. That is, even small language models are "superhuman" at predicting the next token. That being said, it seems plausible that humans can consistently beat the smaller 2017-era models (though not modern models) with a few hours more practice and strategizing. We conclude by discussing some of our takeaways from this result. 

We're not claiming that this result is completely novel or surprising. For example, FactorialCode makes a similar claim as an answer on this LessWrong post about this question. We've also heard from some NLP people that the superiority of LMs to humans for next-token prediction is widely acknowledged in NLP. However, we've seen incorrect claims to the contrary on the internet, and as far as we know there hasn't been a proper apples-to-apples comparison, so we believe there's some value to our results.

If you want to play with our website, it’s here; in our opinion playing this game for half an hour gives you some useful perspective on what it’s like to be a language model.