Editing Fitts's law (section)

== Movement ==
A movement during a single Fitts's law task can be split into two phases:<ref name="Graham"/>

* ''initial movement''. A fast but imprecise movement towards the target
* ''final movement''. Slower but more precise movement in order to acquire the target

The first phase is defined by the distance to the target. In this phase the distance can be closed quickly while still being imprecise. The second movement tries to perform a slow and controlled precise movement to actually hit the target.
The task duration scales linearly in regards to difficulty.<ref name="Graham"/> But as different tasks can have the same difficulty, it is derived that distance has a greater impact on the overall task completion time than target size.

Often it is cited that Fitts's law can be applied to [[eye tracking]]. This seems to be at least a controversial topic as Drewes showed.<ref name="Drewes2011">{{cite book |last1=Drewes |first1=H. |title=Eye Gaze Tracking for Human Computer Interaction |chapter=Dissertation |publisher=LMU München: Fakultät für Mathematik, Informatik und Statistik |year=2011 }}</ref> During fast [[Eye movement#Saccades|saccadic eye movements]] the user is blind. During a Fitts's law task the user consciously acquires its target and can actually see it, making these two types of interaction not comparable.