How we change what others think, feel, believe and do
Focus and Attention
If you look at a picture where some things are in focus and some are not, then your attention will be drawn to the things in focus and away from the things that are out of focus.
A photograph has one flower in focus and other flowers out of focus. Attention is naturally drawn to the flower that is in sharp focus.
Movie makers deliberately alternate the plane of focus between two people as each is talking. This helps shift attention of audience members to the appropriate character.
In practice, the human eye focuses on only one very small area at once. The brain then helpfully fills in the rest, but often of quite low resolution and consequent limited focus.
When we are seeking lines to follow and hence identify shapes, we find it easier to trace the sharp outlines of things that are in focus as opposed to working out the fuzzy outlines of poorly focused items.
Our eyes naturally focus on the point of interest in front of us, literally changing shape so we see the interesting thing more sharply. In evolutionary terms, this is useful for assessing threats and opportunities.
We can still see and identify most things which are out of focus, but our minds are relatively lazy and go first to the things which are easier to distinguish.
In images, make only those things that are of interest in focus. Reduce the focus on other items, perhaps keeping them easily interpreted if they help give an appropriate context, otherwise making them more defocused to avoid distracting the eye.