Figure 2: Characterization of learning algorithms for two-hidden-layer feedforward networks trained to classify MNIST digit images.

(a) Task performance. Shaded regions show standard deviations across 5 seeds. PFA and PFA-o curves are almost overlapping with the BP curve, suggesting a close approximation. (b-e) Backward-forward weight alignment for FA/SF, and path alignment for PFA/PFA-o (top). Backward-forward weight norm ratio for FA/SF, and path norm ratio for PFA/PFA-o (bottom).