How Hybrid NoPE Models Learn Position Without Position Encodings

Zyphra Research explains how hybrid language models recover positional information even when global attention layers use no explicit position encoding. Local layers such as sliding window attention and gated linear attention create a recency bias in the residual stream, and global NoPE attention learns query and key projections that read it out as an implicit relative position encoding. The findings offer a mechanistic account of why interleaving local mixing with global NoPE attention works well and point to positional representations that extrapolate beyond training sequence lengths.