Sounds promising, right? I spent some time trying [perplexity], but results were disappointing—plenty of false positives and false negatives, and no reasonable threshold could be set.
Perplexity was widely considered SOTA in 2022. One part of it is because everyone was evaluating on open models or closed models that were still close (i.e. GPT-2 vs. GPT-3.5). Today, the gap is so much wider between the models you can use to compute perplexity and the frontier models people actually use.
Also so many AI text detection papers used a strawman RoBERTa baseline that was very undertrained for the task.
The synthetic mirrors method for data generation used here is the same as what we use at Pangram. Good blog post, thank you for sharing!