Effective depth shows transformer layers are redundantly correlated

A new scalar diagnostic aggregates layer-wise similarity and finds 15 of 16 language models below a structural reference, indicating correlated updates rather than unused depth.

Big Tech
Barak Gahtan · Ido Galil · Alex M. Bronstein

Technion Israel Institute of Technology · Nvidia · ISTA Institute of Science and Technology Austria

Research Digest··3 min read
Gahtan et al.

The authors propose a diagnostic, effective depth (D_eff), which converts the layer-wise residual stream into a similarity autocorrelation profile and aggregates it into one number.

Why this paper

From Nvidia and 2 others

In one line

Transformer residual streams have an effective depth below 2 layers, regardless of their nominal layer count.

What we could check

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  • ✓Limitations stated by the authors (2 noted)
  • ·No benchmark numbers found

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