Second author here with a link to the arXiv paper: https://arxiv.org/abs/2008.02637 Although I have to say, VentureBeat did much better than most media outlets I have seen writing about current research and what they write is not only accurate but also largely devoid of hype. Perhaps we actually managed to “keep the hype down” as we intended when writing this piece? I will check in on this post now and then if you ha…
Nice paper and important work. Given that nearest-neighbor outperforms on closed book, is it reasonable to suspect the model is doing NN itself internally (which would explain the good performance on close duplicates?) And if this is the case do you think training-time processing of data to attempt to move convert it to question/answer form data rather than raw QA would be a reasonable approach towards tackling this?
> Given that nearest-neighbor outperforms on closed book, is it reasonable to suspect the model is doing NN itself internally (which would explain the good performance on close duplicates?)
I think this is definitely the case for the BART model. It is essentially acting as a QA-pair memorizer over the training data, and at test time, it just matches the question onto those seen at training time. Note that the T5-11B+SSM closed-book model was able to do a little better on NQ, so very large models with task-specific pretraining objectives do seem to do something slightly more interesting than just NN, but still really struggle in some settings.
> And if this is the case do you think training-time processing of data to attempt to move convert it to question/answer form data rather than raw QA would be a reasonable approach towards tackling this?
Great question! Converting sentences into a series of QA pairs is something we're really interested in. The T5-11B+SSM model we evaluate in the paper uses a special "Salient span masking" pretraining objective that does this to some extent (only mask words at pretraining time that are likely to be "answers" to factual questions), so in essence the pretraining task becomes pretty standard cloze-question answering, and they find that leads to better downstream results (https://arxiv.org/abs/2002.08910)