Two magic pixels free download
hand movement and cursor movement) is varied. This comparison reveals that not only does the Shannon form of Welford's model better predict movement times, but it is also more robust when control-display gain (the ratio between e.g. Therefore, this model can be directly compared against the Shannon form of Fitts's law using the F-test of nested models. The formula reduces to the Shannon form when k = 1. This addition was introduced by Kopper et al. The influence of the angle can be weighted using the exponent. Now the users position can be accounted for. The additional parameter k allows the introduction of angles into the model. The formulation of Fitts's index of difficulty most frequently used in the human–computer interaction community is called the Shannon formulation: 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.īits per second: model innovations driven by information theory During fast saccadic eye movements the user is blind. This seems to be at least a controversial topic as Drewes showed. Often it is cited that Fitts's law can be applied to eye tracking. 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. The task duration scales linearly in regards to difficulty. The second movement tries to perform a slow and controlled precise movement to actually hit the target. In this phase the distance can be closed quickly while still being imprecise. The first phase is defined by the distance to the target. Slower but more precise movement in order to acquire the target A fast but imprecise movement towards the target Despite its flaws, this form of the model does possess remarkable predictive power across a range of computer interface modalities and motor tasks, and has provided many insights into user interface design principles.Ī movement during a single Fitts's law task can be split into two phases: Notice that because the ID term depends only on the ratio of distance to width, the model implies that a target distance and width combination can be re-scaled arbitrarily without affecting movement time, which is impossible. The model's predictive power deteriorates when both are varied over a significant range.
![two magic pixels free download two magic pixels free download](https://att.pindiy.com/data/attachment/forum/threadcover/85/07/330907.jpg)
Many experiments testing Fitts's law apply the model to a dataset in which either distance or width, but not both, are varied. This early work, according to Stuart Card's biography, "was a major factor leading to the mouse's commercial introduction by Xerox". The first human–computer interface application of Fitts's law was by Card, English, and Burr, who used the index of performance ( IP), interpreted as 1⁄ b, to compare performance of different input devices, with the mouse coming out on top compared to the joystick or directional movement keys. Since shorter movement times are desirable for a given task, the value of the b parameter can be used as a metric when comparing computer pointing devices against one another.
![two magic pixels free download two magic pixels free download](https://www.twomagicpixels.com/sample-images/having-fun-with-winnie-two-magic-pixels.jpg)
W can also be thought of as the allowed error tolerance in the final position, since the final point of the motion must fall within ± W⁄ 2 of the target's center.