Given a photo, we identify and group its components in various ways to eventually arrive at the most likely interpretations for that photo. Gestalt psychology says we do this by organizing and grouping the elements of a photo based on the following principles:
In Gestalt terms, these organizing principles help us to determine which perceptions will emerge as "figure", and which perceptions will recede into "ground". The "configurations" that come to the forefront are based on our needs and experience - thus our inclination to interpret images in a predictable manner.
Gestalt theory also suggests that pattern takes precedence over the components of the pattern, as when a row of dots is more significant to us than the dots themselves. Thus the "whole is greater than the sum of its parts".
Just as we group items based on gestalt principles, we also ungroup them to make them look unique and singular. This is the basis for creating variety and interest in a photo.