"Bidirectional" Reading Let a Model Truly Understand Context for the First Time
The most core innovation of the BERT model lay in its "bidirectional" training — earlier language models could mostly only process text one-directionally from left to right, while BERT, by randomly masking some words in a sentence and requiring the model to predict them combining the complete context before and after, let the model for the first time truly understand context "bidirectionally," a design that let BERT greatly surpass the previous best on many natural-language-understanding benchmarks, and made the "pretrain-then-fine-tune" R&D paradigm the standard workflow of the whole NLP field thereafter.