Comment by olliepro

The causal masking means future tokens don’t affect previous tokens embeddings as they evolve throughout the model, but all tokens a processed in parallel… so, yes and no. See this previous HN post (https://news.ycombinator.com/item?id=45644328) about how bidirectional encoders are similar to diffusion’s non-linear way of generating text. Vision transformers use bidirectional encoding b/c of the non-causal nature of image pixels.