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gwern's avatar

> This might explain why ChatGPT is so much worse at writing modern poetry (which is tightly restricted by copyright law) than it is at writing in older styles. For instance, it seems to me to be much better at writing a Samuel Johnson essay about kangaroos than it is at writing a modernist poem about same.

No, you've simply run into the RLHF mode collapse problem (https://www.lesswrong.com/posts/t9svvNPNmFf5Qa3TA/mysteries-of-mode-collapse?commentId=tHhsnntni7WHFzR3x) interacting with byte-pair encoding (https://gwern.net/gpt-3#bpes). A GPT doesn't genuinely understand phonetics due to the preprocessing of the data destroying individual-letter information and replacing them with large half-word-sized chunks, and then during RLHF, it avoids writing anything which doesn't make use of the memorized pairs of rhymes because it's unsure what rhyming or nonrhyming poetry looks like.

(If you are skeptical, try asking ChatGPT this simple prompt: "Write a nonrhyming poem." a dozen times and count how many times it actually does so rather than rhyming. Last time I checked, the success rate was still well under 20%.)

The Ea-Nasir screenshot also shows the effects of the RLHF, I suspect. My advice would be to minimize use of GPT in favor of Claude for all historical scenarios involving anything less wholesome than _Barney & Friends_. While the model is not as good, the RLAIF of Claude seems to be a good deal less indiscriminate & crippling.

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Andrew Chapman's avatar

This is fascinating - thank you. Hard not to wonder whether the talking rat has been borrowed by ChatGPT from the BBC's Horrible Histories franchise.

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