Gestalt theory says that the mind makes sense of the world by selecting and organizing the many elements of a scene into figure and ground, where "figure" is comprised of preferred recognizable shapes and "ground" is composed of everything else. Thus "figure" comes to the forefront of our consciousness, while the "ground" recedes.
Within a photo, the
Generaly, the positive space includes the subject of the photo, while the negative space includes the background.
We have a builtin preferrance for a balance of the positive and negative spaces in a photo. Creating this balance involves shooting from a better camera angle, bluring using a shallow depth-of-field, selective framing prior to the shot, or cropping after the shot.
However, a deliberate inbalance can be used effectively to change the impact of a photo, as when the subject is made to dominate the photo's space.
When looking at a photo, our eyes often begin at the frame and move inside. We find entry into the photo to be easier when some part of the positive space touches the frame, as when a tree branch begins on the left frame and moves inward towards the bluejay sitting on the branch.
As you photograph (mentally or otherwise), strive to see the positive and negative spaces of a photo. Practice framing or cropping your shots to determines how balance or lack of balance impacts the photo. Last, note the entry points into the photo, i.e., the path the eye takes as it crosses the frame to access the subject.