Attention, memory and perception
Visual hierarchy
Also called Visual anchors
The order in which people notice things on a screen, set by size, contrast, colour, spacing and position.
People don't read a screen top to bottom; they scan, stopping at whatever stands out. Hierarchy decides what they see first, second and not at all.
Make the most important thing the most prominent, and let everything else step back. Squint at a design: what still stands out is what people will see first.
In practice
A checkout where the order total and the pay button are the largest, highest-contrast things on the screen.
Common mistake
Giving everything equal weight, or making secondary actions as loud as the primary one, so people can't tell where to look.
Where it comes from
Draws on Gestalt psychology from the 1920s and on eye-tracking research such as Nielsen Norman Group's 2006 finding that people scan web pages in an F-shaped pattern.