Muscle memory and User Interface Design
Placement consistency of graphics in a user interface system not only helps users learn the system, it helps their muscles “learn” the system as well. A user’s constant and continual use of a product’s UI causes their muscles to “memorize” certain movements and actions.
For example, when a user’s muscle memory tells them that the “Save” button is always in the lower right corner, the user will eventually go to that spot through muscle memory without requiring any visual confirmation that the “Save” button is actually there. This is one reason why consistency in graphical placement within a user interface system is so important.