Synonyms: principles of grouping, the law of perceptual organization
Law of Prägnanz states that people perceive complex things as simplified forms in order to easily recognize the world around them. Therefore, people can perceive things as a whole or the sum of simple parts. Yes, our mind and eyes tend to simplify everything as much as possible.
“Prägnanz” is a German word that means salience, conciseness, and orderliness.
The law of Prägnanz is the fundamental principle of the Gestalt laws of grouping. Gestalt laws are rules which describe how humans perceive visual elements and simplify complex images.
Look at the picture below. What do you see in it?
Most likely the image on the left reminds you of an atom, on the right — a flower. You don’t see them as a group of curves and new forms appeared when all these curves meet each other. Instead of that you are trying to identify familiar objects.
Pretty much the same way you can apply this principle to UI. Users see your interface as a whole and this means two things.
- If you want to ease the user's perception use simple forms and group them in obvious and expected way.
- If you want to highlight an element, well, break this rule, but try to avoid chaos. Breaking rules is effective only when it contrasts order.