The use of relative size to indicate the relative importance of the objects or people being depicted.

Hierarchical scaling

Explanation:

Hierarchical scaling is a technique where the artist or the author of the artwork uses a relative size to indicate the importance of the depicted items.

It is primarily used in sculpting and painting to show that some objects are more important than others. For instance, in a painting which depicts Royalty, Nobility and the Common citizenry, you might find a situation where the Royals are painted unnaturally larger than the Nobles who would be larger than the citizens.