“One of the most well-understood and salient principles underlying the ergonomics of graphical user interface design is Fitts’ Law. Named for Paul Fitts, a psychologist at Ohio State University, Fitts’ Law is a mathematical model of fine motor control which predicts how long it takes to move from one position to another as a function of the distance to and size of the target area. Papers outlining what became known as Fitts’ Law were published in 1954 and 1964.” (Jensen Harris – An Office User Interface Blog)