Anticipation is used to prepare the audience for an action, and to make the action appear more realistic. It is used to give the character almost an intelligence, as if they have thought about what they are about to do. It is used to give the audience the sense that the characters have emotions, thought processes and personalities.
Most obvious examples would be things like a pitcher about to throw a baseball. The technique can also be used for less physical actions, such as a character looking off-screen to anticipate someone’s arrival, or attention focusing on an object that a character is about to pick up.
The Animators Survival Kit, Richard William’s quotes (or paraphrases) a couple of “performance” greats on the subject of Anticipation.
“There are only three things in animation, 1 – Anticipation, 2 – Action, 3 – Reaction.”
Charlie Chaplin also made a quote that describes the principle perfectly
“1 – Tell ‘em what you’re going to do, 2 – do it, 3 – Tell ‘em what you’ve done.”
Here is an example of the different stages of a character punching.
Below is an animated example of a baseball pitcher.
Below is a example that I have created show the anticipation as we wait for the actual jump: