An action occurs in three parts:
Anticipation can be the anatomical preparation for the action, e.g., retracting a foot before kicking a ball. It can also be a device to attract the viewer's attention to the proper screen area and to prepare them for the action, e.g., raising the arms and staring at something before picking it up, or staring off-screen at something and then reacting to it before the action moves on-screen. An example of this is the opening scene of Luxo, jr.. The father is looking off-screen and then reacts to something. This sets up the viewers to look at that part of the screen so they are prepared when Luxo, jr. hops in from off-screen.
A properly timed anticipation can enable the viewer to better understand a rapid action, e.g., preparing to run and then dashing off-screen.
Anticipation can also create the perception of weight or mass, e.g., a heavy person might put their arms on a chair before they rise, whereas a smaller person might just stand up.