Adaptive Computation Depth via Learned Token Routing in Transformers

Fuente: arXiv
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Autor principal: Mohammed, Ahmed Abdelmuniem Abdalla
Formato: Preprint
Publicado: 2026
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author Mohammed, Ahmed Abdelmuniem Abdalla
author_facet Mohammed, Ahmed Abdelmuniem Abdalla
contents Standard transformer architectures apply the same number of layers to every token regardless of contextual difficulty. We present Token-Selective Attention (TSA), a learned per-token gate on residual updates between consecutive transformer blocks. Each gate is a lightweight two-layer multi-layer perceptron (MLP) that produces a continuous halting probability, making the mechanism end-to-end differentiable with 1.7% parameter overhead and no changes to the base architecture. Notably, TSA learns difficulty-proportional routing without any explicit depth pressure: even at $λ=0$ (no depth regularisation), the task-loss gradient alone drives the router to skip 20% of token-layer operations. On character-level language modeling, TSA saved 14-23% of token-layer operations (TLOps) across Tiny-Shakespeare and enwik8 at <0.5% quality loss. At matched efficiency, TSA achieved 0.7% lower validation loss than early exit, and the learned routing transfers directly to inference-time sparse execution for real wall-clock speedup.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05222
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Adaptive Computation Depth via Learned Token Routing in Transformers
Mohammed, Ahmed Abdelmuniem Abdalla
Machine Learning
Artificial Intelligence
Standard transformer architectures apply the same number of layers to every token regardless of contextual difficulty. We present Token-Selective Attention (TSA), a learned per-token gate on residual updates between consecutive transformer blocks. Each gate is a lightweight two-layer multi-layer perceptron (MLP) that produces a continuous halting probability, making the mechanism end-to-end differentiable with 1.7% parameter overhead and no changes to the base architecture. Notably, TSA learns difficulty-proportional routing without any explicit depth pressure: even at $λ=0$ (no depth regularisation), the task-loss gradient alone drives the router to skip 20% of token-layer operations. On character-level language modeling, TSA saved 14-23% of token-layer operations (TLOps) across Tiny-Shakespeare and enwik8 at <0.5% quality loss. At matched efficiency, TSA achieved 0.7% lower validation loss than early exit, and the learned routing transfers directly to inference-time sparse execution for real wall-clock speedup.
title Adaptive Computation Depth via Learned Token Routing in Transformers
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.05222