Designed for Use, 2nd Edition

Chapter 17 Fitts’s Law

Usability has very few universally accepted laws. Fitts’s law is one of these few. It basically states that people can hit a target more quickly if the target is bigger or closer to the user’s mouse cursor (on a desktop system). The target could be a screen icon users are trying to click with a mouse cursor or a button they are trying to tap on a touch screen.

The direction of the motion matters. The target object’s size should correspond to the direction of the motion:

This idea seems pretty straightforward, and indeed, ...