A method for evaluating head-controlled computer input devices using Fitts' law. Hum Factors.
Towards a standard for pointing device evaluation, perspectives on 27 years of Fitts' law research in HCI.
Even though existing discussions on whether the Fitts' law is suitable for eye movement  and limitations of Fitts' law to achieve accurate results when ID is close to zero , , this law is still actually used in system usability testing and the only usability related quantitative law proved by experiments.
The aim of this work is to analyse how the slope parameter changes in Fitts' law when different user's motivation level exists.
Fitts' law states that the speed of a movement is related to the distance of the movement and the size of the target (Fitts, 1954).
Fitts' law indicates that the size of the target (i.e., the button) and the distance of the movement will influence performance, and this was true for both younger and older adults, although the slope of the function was larger for older adults.
Five subjects (4 who participated in study aim 2 and 1 who did not) were tested to assess control performance using our evaluation protocol adaptation of Fitts' law, the results of which are summarized in Figure 7 and detailed in Table 4.
To allow us to evaluate the transducer's performance, we developed an evaluation protocol based on Fitts' law. An evaluation procedure such as the one described here is generally applicable to any prosthetic limb control mechanism.
As 3-D display applications are becoming more popular, how well Fitts' law holds in 3-D target acquisition tasks, and thus how useful it is in evaluating 3-D systems, becomes an important question.
Therefore these studies demonstrated that with some modifications, Fitts' law can be extended to describe target acquisition performance within a 3-D environment.
Comparison of six cursor control devices based on Fitts' law
In this experiment, only one parameter was varied in the Fitts' law
equation: the distance between targets.
A review of the literature indicates that studies using Fitts' law
to predict the effects of lag have concentrated on manually controlled tasks and not on head-controlled tasks.
is a useful predictor of placement performance, though less so when difficulty or the degrees of freedom in the task are high or SR is poor.
The results of their study supported Jagacinski and Monk's findings that Fitts' law
aptly described head movement in computer-related tasks and that performance for diagonal head movements was slower than for movements along the vertical or horizontal axis.