It’s something that’s wired into us at a neurological level –while our brains feel satisfied with symmetry, adding an odd number of things makes our brain feel challenged and compositions feel more dynamic.
Three is the smallest number we can use to form a distinguishable pattern in our heads. When you see an odd number of things, your eye is forced to move around more, making for a more engaging visual experience.
As graphic designers, you’ll see the concept of threes popping up all over the place – large numbered lists or icons all with three things. When creating grids for layouts at their simplest form, we’ll use a three-column grid (yes, I know that other column grids exist, but often these will be secretly hiding a much more complex structure of six, nine, or twelve columns so divisible into three).
And it’s not just graphic designers. Interior designers use it in their compositions, arranging clusters of objects in odd numbers. Photographers use the principle to make their shots more interesting – it’s as simple as dividing up the view into thirds and aiming to have the focus on one of these divisions. Modern cameras often have this as a setting that you can add to the viewfinder, and when we’re cropping images we’ll often set them off-centre to create more interest in the subject.
Easy to do; great effect.