Fitts’ Law: Appreciating Size, Space and Speed.



Playstation would have been a failure if its controller was like THAT. Period.

Fitts’ Law, in interaction design, describes the time taken to point at a target based on the size of and the distance to the object. It is governed by the following law:


T = k log2 (D/S + 1.0)


T = time to move the pointer to a target

D = distance between the pointer and the target

S = size of the target

k is a constant of approx. 200ms/bit

Essentially, the aim of using Fitts’ Law is to help designers determine the location and size of buttons, as well as the spacing between them so as to enhance user experience. This is an especially important point to note in cases with limited space, for example mobile devices. A trade-off always exists among the size of the object, the distance between the objects, and the speed and accuracy of getting to that object; the following video sums this up (embedding disabled, kindly click on the link):


The importance of Fitts’ Law should not be ignored, and even more so when the time to physically locate an object is critical to the task at hand – pressing the “shoot” button to score the championship-winning goal in the final minute of a soccer match in FIFA 13 after a mazy dribble through the opponent’s entire team. Now that’s critical!

And back to my Playstation…


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