Fitts's Law

Fitts' law (often cited as Fitts's law) is a model of human movement primarily used in human–computer interaction and ergonomics that predicts that the time required to rapidly move to a target area is a function of the distance to the target and the size of the target. Fitts's law is used to model the act of pointing, either by physically touching an object with a hand or finger, or virtually, by pointing to an object on a computer monitor using a pointing device. It was proposed by Paul Fitts in 1954.