Underscoring the Problem: Why Softpick Fails at Initialization

Abstract:Softmax attention gives every token a nonzero weight, which in trained models concentrates into attention sinks and massive activations that widen the dynamic range low-precision inference must cover. Softpick removes this constraint by rectifying scores, eliminating sinks and lowering hidden-state kurtosis, but its advantage fades at scale. We reframe this failure as a normalization problem. Softpick's denominator splits into positive- and negative-shifted sums $D^+$ and $D^-$, used identically in the forward and backward pass, preventing their roles from being isolated. We separate them into a family of operators that independently choose each denominator. The failure originates at initialization: every layer contains rows where $D^+$ is exactly zero, while near-dead rows produce gradient norms above $10^{12}$ regardless of the backward denominator. Only Softpick and a stop-gradient variant, which keeps $D^+ + D^-$ forward but backpropagates through $D^+$ alone, train from scratch. At 230M parameters, the stop-gradient operator matches Softpick on quantization, has fewer dead heads, and retrieves passkeys more reliably, trailing only on peak attention-weight kurtosis.

Machine Learning (cs.LG)

arXiv:2610.05488 [cs.LG]

(or arXiv:2610.05488v1 [cs.LG] for this version)

https://doi.org/10.48550/arXiv.2610.05488 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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