The idea of Scale to a graphic designer is a very useful skill to implement into a design. In Graphic Design: The New Basics defines scale as the size that objects are in relation to the design as a whole. Scale can be objective, which refers to the actual size it has in relation to the real life object, or it can be subjective which refers to the object in relation to objects around it. Scale can add or decrease importance to certain objects when looked at relatively from other objects. Scale can add depth to a design by making objects smaller in scale and contrasting it with objects bigger in scale to make the illusion of a 3-dimensional space through forced perspective.
In my example given above you can see how scale is used throughout the page. In the first frame you can see a smaller version of the same girl in the background. The artist used this technique of framing to illustrate that this is a photo of her. In the first frame at the bottom of the page you can see scale being used between the dentist, the girl, and the nurse to show depth in the scene, with the dentist being in the foreground and the girl in the chair and the nurse, both smaller in scale slightly, look to be behind him.