For example, one study found that when people agree that a graphic design is good, they exhibit more similar eye movements; measured by the Fréchet distance.
[2] The concept of visual hierarchy is based in Gestalt psychological theory, an early 20th-century German theory that proposes that the human brain has innate organizing tendencies that “structure individual elements, shapes or forms into a coherent, organized whole,” especially when processing visual information.
[4] When an element in a visual field disconnects from the ‘whole’ created by the brain's perceptual organization, it “stands out” to the viewer.
The "squint test" is often suggested as a simple, if unscientific, method to evaluate the visual hierarchy of a graphical product like a map or web page.
[8] When viewed out of focus (or from a great distance), the viewer is not distracted by details, but can only see overall (gestalt) patterns such as visual hierarchy.
One could compare visual hierarchy in graphic design to grammatical structure in writing in terms of the importance of each principle to these fields.