Breaking the Rules
'Synthetic rules', or rules that have are derived from abstract concepts, offer opportunities for creative psychological manipulation as well. One such compositional rule suggests placing things like people, animals and vehicles (i.e. things that move and have a definite 'front') in the frame such that they have space in front of them. This is often referred to as 'leading space' or 'nose room', alluding to the idea that the subject should have space to move into in the direction that their nose is pointing. The underlying concept is that a subject placed close to the edge of the frame that they're facing can appear confined or restricted in the scene.
Once we are aware of the concept behind this rule, we can start exploiting it to purposefully alter the image's visual vocabulary. For a given image, do we want to frame a subject in a manner that makes it seem free and unfettered, or do we want to create tension for the viewer by placing our subject nearer to the edge of the frame?
It is possible to create energy in an image and focus the viewer's attention by purposefully violating the nose room rule. A composition that places the subject up against the edge of the frame without leading space can cause the subject to appear much more conspicuous. This can help to bring attention to secondary elements in a photograph, such as an out-of-focus subject in the background.
If a compositional rule is meant to create one effect, we can break that rule in order to deliberately provoke the opposite reaction. Similarly, we can flirt with the theory behind a rule to suggest the same result without being quite as explicit or clichéd. Let's look at an example.
Another common compositional rule involves 'leading lines' - linear elements that draw the eye towards a focal point or primary subject of an image. While this can be a very effective technique, it can also lead to overly-obvious or trite compositions.
One way to bend this rule would be to frame your subject in the middle of several strong linear elements, rather than having the lines in the image lead directly to the subject. This can serve to direct the viewer's attention in a subtle and more interesting fashion.
Earlier, I mentioned that some rules come from common sense or standard practice. Many of these concepts are so ingrained in our stylistic subconsciousness that we don't even consider them to be rules. For example, we shoot landscape scenes with a straight horizon because a slightly crooked horizon looks like a mistake; there's generally no good reason for the horizon to be off-level.
We can use the viewer's expectations of an image (the 'rule of norms', if we may so call it) to startle the viewer out of complacency. While this doesn't mean that we should create images that are simply sloppy, we can change the subject matter or treatment of an image to increase its visual impact.