Does task specific prefix matters for T5 fine-tuning?

Beginners
#1

If I understand correctly pre-trained T5 models were pre-trained with an unsupervised objective without any task specific prefix like “translate”, “summarize”, etc. Is it important then to create my summarization dataset for fine-tuning in a way that every input starts with "summarize: "?

#2

I think it is important, but am not totally certain why. You could test it pretty easily I bet.

#3

Actually, it may not be very important.
I am confused about the prefix too and ask on the Github. And one of the code author replied. (there are more questions, you may benefit from it too as a beginner)

#4

I think the question is if the released pre-trained models were trained on a mixture of supervised and unsupervised tasks (so they learned with prefixes and putting them in front of my input when fine-tuning is useful) or only on unsupervised tasks. I know they do it both ways in the paper but not clear which one was released.

#5

Use prefix if your task is similar to one of the pre-trained tasks, otherwise it really doesn’t matter (at least I have observed this in my own experiments)

2 Likes
#6

Released models were pret-rained on both supervised and unsupervised tasks so prefix should help. See https://github.com/google-research/text-to-text-transfer-transformer/issues/314#issuecomment-665764712

2 Likes
#7

Yes, that’s what I said, if task is similar to one of the tasks used in the pre-training mixture then it helps, if it’s completely different then it won’t matter

#8

Yes, that part was clear. I just wanted to clarify how the released models were trained. Although you are right, the answer was implicit in what you already said.

#9

Great part is that T5 performs really well with and without prefix :smile: Here’s what I observed in my experiments.,

  1. It converges slightly faster when using a task prefix and when the task was similar, say summarization
  2. Performed equally well even without prefix, took slightly longer to converge
4 Likes
#10

My question is related, how can I understand how prefix and prefix masking is working? where can I read the code related to processing the prefix? or there is nothing special about that? I mean it is simply adding a task in the config file? is the idea as simple as that?