Neural networks trained with backpropagation, the standard algorithm of deep
learning which uses weight transport, are easily fooled by existing
gradient-based adversarial attacks. This class of attacks are based on certain
small perturbations of the inputs to make networks misclassify them. We show
that less biologically implausible deep neural networks trained with feedback
alignment, which do not use weight transport, can be harder to fool, providing
actual robustness. Tested on MNIST, deep neural networks trained without weight
transport (1) have an adversarial accuracy of 98% compared to 0.03% for neural
networks trained with backpropagation and (2) generate non-transferable
adversarial examples. However, this gap decreases on CIFAR-10 but is still
significant particularly for small perturbation magnitude less than 1/2.