Anticipation

In animation, we have an opportunity to exaggerate real life.

Everything goes back before it goes forward, left before it goes right, up before it goes down.

This is to give the viewer notice of what is about to happen.

Often, the anticipation is more important than the actual action. For example, with the hunter in Snow White, we never actually see him take her life but the anticipation adds to the drama to such an extent that we don't need to.