I am searching momentum. And below animated gif shows one advantage of momentum. And the momentum is expressed like this:
$\mathbf{W}^{k+1}$ = $\mathbf{W}^{k}$ – η $\frac {\partial E}{\partial \mathbf{W}}$ + γ$\mathbf{W}^{k – 1}$
My question is why can the momentum escape from the saddle point after losing the magnitude of the gradient, namely although the momentum is about to be almost settled while the SGD can't escape. I read this discussion and I googled a lot. So, in some case the momentum can escape from a saddle point while the normal SGD can't. However, in this animated gif I can't explain why the momentum can escape.
Could anyone explain this?