Exaggeration
Exaggerating an action or a movement can make the movement seem more real when used in animation.
Perhaps the most widely used exaggerations, in animations, are in facial expressions. If you have ever seen the movie “Final Fantasy: the Spirits Within” you may understand the need to exaggerate facial expression. In "Final Fantasy" the movement seems wrong but that is because there was not enough movement put in the lips while the characters were talking.
When you watch cartoons such as the ones that Walt Disney Studios produces it is easy to see the change in facial expressions. They’re almost always exaggerated but this makes them seem more real. However, the animator should be careful not to over exaggerate things because that tends to make the movements seem bizarre.The principle of exaggerating movements is also used in theater.
