So if I understand correctly there are mainly two ways to adapt BERT to a specific task: fine-tuning (all weights are changed, even pretrained ones) and feature-based (pretrained weights are frozen). However, I am confused.
- When to use which one? If you have unlabeled data (unsupervised learning), should you then use fine-tuning?
- If I want to fine-tuned BERT, isn't the only option to do that using masked language model and next sentence prediction? And also: is it necessary to put another layer of neural network on top?
Thank you.