Altering Backward Pass Gradients improves Convergence

TL;DR

This paper introduces PowerGrad Transform, a simple method to modify backward pass gradients, which improves neural network convergence and accuracy without additional computational cost.

Contribution

It proposes a novel decoupled training technique that alters gradients in the backward pass to enhance convergence and final accuracy.

Findings

Improves ResNet-50 accuracy by 0.73% on ImageNet.

Enhances training efficiency and convergence speed.

Easy to implement with minimal code changes.

Abstract

In standard neural network training, the gradients in the backward pass are determined by the forward pass. As a result, the two stages are coupled. This is how most neural networks are trained currently. However, gradient modification in the backward pass has seldom been studied in the literature. In this paper we explore decoupled training, where we alter the gradients in the backward pass. We propose a simple yet powerful method called PowerGrad Transform, that alters the gradients before the weight update in the backward pass and significantly enhances the predictive performance of the neural network. PowerGrad Transform trains the network to arrive at a better optima at convergence. It is computationally extremely efficient, virtually adding no additional cost to either memory or compute, but results in improved final accuracies on both the training and test sets. PowerGrad Transform is easy to integrate into existing training routines, requiring just a few lines of code. PowerGrad Transform accelerates training and makes it possible for the network to better fit the training data. With decoupled training, PowerGrad Transform improves baseline accuracies for ResNet-50 by 0.73%, for SE-ResNet-50 by 0.66% and by more than 1.0% for the non-normalized ResNet-18 network on the ImageNet classification task.