Editing Fitts's law (section)

== Temporal targets ==
Fitts's law deals only with targets defined in space. However, a target can be defined purely on the time axis, which is called a temporal target. A blinking target or a target moving toward a selection area are examples of temporal targets. Similar to space, the distance to the target (i.e., temporal distance ''D''<sub>t</sub>) and the width of the target (i.e., temporal width ''W''<sub>t</sub>) can be defined for temporal targets as well. The temporal distance is the amount of time a person must wait for a target to appear. The temporal width is a short duration from the moment the target appears until it disappears. For example, for a blinking target, ''D''<sub>t</sub> can be thought of as the period of blinking and ''W''<sub>t</sub> as the duration of the blinking. As with targets in space, the larger the ''D''<sub>t</sub> or the smaller the ''W''<sub>t</sub>, the more difficult it becomes to select the target.

The task of selecting the temporal target is called ''temporal pointing''. The model for temporal pointing was first presented to the [[human–computer interaction]] field in 2016.<ref>{{Cite book|last1=Lee|first1=Byungjoo|last2=Oulasvirta|first2=Antti|title=Proceedings of the 2016 CHI Conference on Human Factors in Computing Systems |chapter=Modelling Error Rates in Temporal Pointing |date=2016|series=CHI '16|location=New York, NY, USA|publisher=ACM|pages=1857–1868|doi=10.1145/2858036.2858143|isbn=9781450333627|s2cid=12949535 }}</ref> The model predicts the error rate, the human performance in temporal pointing, as a function of temporal index of difficulty (''ID''<sub>t</sub>):

<math display="block">\text{ID}_{t} = \log_2 \Bigg(\frac{D_{t}}{W_{t}}\Bigg)</math>