Fitts' Law

A predictive model of human movement.

Law

Closer and bigger targets are easier to select than small and far ones. The time required to move to a target area is a function based off the distance to the target and the width of the target. $T=a+b{\log }_2(\frac{D}{S+1})$

• $T$ is the time to move
• $a$ is the intercept where $T=0$ (empirically derrived)
• $b$ is the slope (empirically derrived)
• $D$ is the distance
• $S$ is the size