In this recent spring term, when I still resided in the cold yet lovely Copenhagen, I participated in the User Interface Technologies course where we toyed around with an Arduino to build a simple colorimeter, used the kinect for text input while being dressed up as a gorilla, and finally built an interactive Fitts’s experiment. Fitts and the infamous Fitts’s law he proclaimed date back to the 1950s but it is still of great relevance to today’s user interface technology research and evaluation.

Fitts’s Law is rather simple and what it basically says is that the difficulty of a target acquisition task is a function of the distance from start point to the target area and the size of the target area. It allows you to compute an index of difficulty and the good thing about it is that it nicely linearly correlates with the time users take to complete the task.

‘nough said, here is the interactive Fitts’s experiment (, with even more explanations and references. We developed it in a group of four, and as usual the source code is available under the permissive MIT license.