“Is GPT 2XL already clean?” by Jasper Blank

LessWrong (30+ Karma) · Oct 26, 2026 · 12m

In which I investigate if Opus is able to interpret neurons better than GPT 4.

TLDR: Opus 5.5 is able to identify 3-19% of the neurons of GPT 2-XL based on activations. This is a big improvement over the 0.3% that GPT-4 was able to achieve in 2023.

#AI notice: This post is human written but in the research there was heavy use of Opus 5.5. I mainly asked it to rerun this 2023 paper to see how big the improvement is if Opus 5.5 is used instead of GPT4.

Since the invention of Large language models they have been stubbornly refusing to be clear. They have been described as black boxes and as…