There's a pretty common street fighting move of stomping with the forward foot while you throw a punch. An untrained opponent will glance down and you pop them

There's a pretty common street fighting move of stomping with the forward foot while you throw a punch. An untrained opponent will glance down and you pop them during the saccade. It's even explicitly part of the "proper" technique in some martial arts that allow both hand and foot strikes. After it gets you a few times you just learn not to look but there's no general defense against the idea I don't think, just specific applications of it.