English

Attention Projection Mixing with Exogenous Anchors

Computation and Language 2026-05-28 v4

Abstract

Cross-layer reuse of early attention projections can improve optimization and data efficiency, but it creates a structural conflict: the first layer must simultaneously act as a stable, reusable anchor for all deeper layers and as an effective computational block. We demonstrate that this tension constrains the performance of internal-anchor designs. We propose ExoFormer, which resolves the conflict by learning exogenous anchor projections outside the sequential layer stack. We introduce a unified normalized mixing framework that mixes queries, keys, values, and gate logits using learnable coefficients (exploring coefficient granularities: elementwise, headwise, and scalar), and we show that normalizing anchor sources is key to stable reuse. ExoFormer variants consistently outperform their internal-anchor counterparts, and the dynamic variant yields 1.5x downstream accuracy points while matching validation loss using 1.5x fewer tokens than Gated Attention. We explain this efficacy via an Offloading Hypothesis: external anchors preserve essential token identity, allowing layers to specialize exclusively in feature transformation. We release code and models to facilitate future research.

Keywords

Cite

@article{arxiv.2601.08131,
  title  = {Attention Projection Mixing with Exogenous Anchors},
  author = {Jonathan Su},
  journal= {arXiv preprint arXiv:2601.08131},
  year   = {2026}
}
R2 v1 2026-07-01T09:01:56.881Z