No. 02 Fitts’s Law

Big buttons close to your thumb are fast to hit.

Tiny ones tucked in a corner mean misses, extra taps… & frustration.

Make the main action big & put it within thumb reach.

Paul Fitts studied cockpits for the US Air Force, where a missed switch is a very bad day.

In 1954 he had people tap back & forth between targets. Bigger & closer meant faster, every time.

In 1978, Xerox researchers tested it on a brand-new gadget: the mouse.

• Paul M. Fitts, “The information capacity of the human motor system in controlling the amplitude of movement,” Journal of Experimental Psychology (1954)
• Card, English & Burr, mouse vs. joystick & keys study, Ergonomics (1978)

Save this for the next time a button feels impossible to tap.