# fitts' law calculator

The visual result is quite natural. How could I make a logo that looks off centered due to the letters, look centered? We are studying Fitts' Law, a model of human motor response developed by Paul Fitts in 1954. When I tracked down the scrap paper I used, I see I set A(1) = 20 pixels. Each 'condition' was repeated 20 times in random order. This later became known as Fitts's law [Fitts 1954]. In 1954, Fitts described the relationship between the target distance, width, and time needed for a target acquisition task. No matter where you place the initial starting point, the Width is going to … The separation between the targets (termed A, for movement amplitude) and the width of the targets (termed W, for target width) could be varied in dif­fer­ent combinations (see figure 6.1). Fitts’ law states that the amount of time required for a person to move a pointer (e.g., mouse cursor) to a target area is a function of the distance to the target divided by the size of the target. This Law states exactly how the time it takes is a function of the combination distance to the object and its size. lists of numbers derived from reality and not created artificially), the first significant digit is usually small. Consistent with this, the b for the touchscreen was smaller than the b for the mouse. Thus, the longer the distance and the smaller the target’s size, the longer it takes. On the other hand, moving the mouse from a checkbox at the bottom of a dialog box to a 70-pixel-wide OK button in the Window’s position (say, 300 pixels away) versus the Mac-position (about 380 pixels) is at most only 11% faster for Windows. For example, you could use your equation to see the impact of moving the target to other places in the window than the bottom right (including places you didn't think of when you did the experiment). Now, can you tell me how to get the value of a and b? It's.. Time = a + b log 2 ( D / S + 1 ) .. where D is the distance from the starting point of the cursor, and S is the width of the target. Has Fitts' Law been adapted to Touch screens? At a minimum your experiment needs two values of ID, but I suggest also including in-between values, just to make sure Fitt's law is "working" in your case. areas Directional stability v. “landing” 24. So MT becomes a, which should be somewhere around the average of click times. For instance, 0.5cm_X_2cm would mean that the ribbons were 0.5cm wide, and 2cm apart. If you want to know how long it takes to slew from the top left to bottom right, forget about Fitt's and run an experiment where users slew from the top left to the lower right and take the average. For example, you can calculate the total time to hit a sequence of buttons in a typical order, and see how it changes with different arrangements of buttons. You have two parameters (a and b), so you need at least two values of ID. Forlines et al. In fitting parameters to a model, you need at least as many conditions as parameters to estimate. Corners -As the mouse cursor stops at the edge of the screen, corners can be considered to have an "infinite" width. ", University of Illinois at Urbana-Champaign. this because I have an example where a user move the mouse from top-left to bottom-right so A = 800 pixels and W = 10 pixels. It provides several estimates based on different Fitts' Law formulas. index of difficulty is zero while the slope (“b”) represents the inverse of the motor system information-processing rate.This lab will involve examination of how changing the difficulty of the movement (and thus the accuracy requirements) affects the speed of movement (measured by movement time). Fitt's law implies that controls on the border of a screen in a desktop application tend to be the fastest to get to. For example, a small object 1 feet meter from your hand takes more time to grasp than a large object; that is, size plays a role. Plot these pairs of values as dots on graph paper with MT on the Y-axis. [2*] “Movement Time Prediction in Human-Computer Interfaces” by S. MacKenzie, [3*] “Fitts Law: Modeling Movement Time in HCI” by H. Zhao. How can you calculate Fitts' Law for something that extends out forever? A target object, in the context of User Interface, can be an interactive element such as a submit button, a hyperlink, and an input field in a web form. Each test had two variables: the width of the ribbons and the space between the ribbons. Fitts’ law is widely applied in user experience (UX) and user interface (UI) design. it is more difﬁcult to calculate because the angle between the starting point and the target object must be known. How large should the logo be for easy clickability? For example an iteration value of 4 means that this is the position of the input device at $400 \, \mathrm{ms}$ from starting the exercise. Fitts’ law can be used as an aid to make educated decisions on the size and placement of user interface elements, so it’s still extremely applicable today, especially to web design. His original study was on pointing with a stylus, but his work is applicable to pointing with a mouse, using touch screens, and the range of pointing devices for 2D displays. It provides several estimates based on different Fitts' Law formulas. 25. According to this paper [1*] and the video [A1] they give an example where W (width of the target) and A (amplitude or distance from initial position to target position) are changed every time they use it. I must've changed my mind when I turned to write up the example, but didn't update the numbers. This implies that, in a pulldown menu, there is a bigger difference in MT between the first and second menu items than between the seventh and eighth menu items, so ordering menu items by frequency of use is more important for the first few menu items than the later ones. Less obvious is that the larger the target (W) the lower the MT, suggesting that commonly used controls should be bigger than rarely used controls. Fitts’ Law predicts that the time to point at an object using a device is a function of the distance from the target object & the object’s size. or can you tell me what kind of experiment that I can do in order to get these two values a and b? Podcast 293: Connecting apps, data, and the cloud with Apollo GraphQL CEO…, MAINTENANCE WARNING: Possible downtime early morning Dec 2, 4, and 9 UTC…. A Web-based Test of Fitts' Law: UC Berkeley Dataset of 94,580 human motion timing measurements. For example, as Forlines et al shows, you shouldn’t use an equation from an experiment with a mouse to predict the MTs of a touchscreen. In "Pride and Prejudice", what does Darcy mean by "Whatever bears affinity to cunning is despicable"? Design Tools FITTS' Law Calculator: FITTS' Law Calculator estimates the time for younger and older adults to move a limb to a target. thegreatone_80. Once you have a and b from the experiment, you can use your Fitt's equation to predict average times of the single particular value of ID you're interested in, although there is not much point in using Fitt's for a single value of ID. We are studying Fitts' Law, a model of human motor response developed by Paul Fitts in 1954. This because they seems to say that “hey, guys this theorem works fine” so they take many different examples, but now my problem is when I want to apply this theorem to the same value of W and A; how can I get value of a and b? one simple question regarding the last example, for A1 = 800 px, and A2= 10, what is the value of W? You can use Fitt’s to determine the upper bound of relative improvement of different places for a control (the percent of time Location 1 takes to move to versus Location 2). If the dots do not distribute evenly around a single straight line (i.e., the cloud of dots curves up and/or down), then Fitt's Law does not apply in your case, for some reason. Acceptable MT ribbons were 0.5cm wide, and A2= 10, what is the value of W a! Mouse cursor stops at the edge of the combination distance to the,. Of IDs our tips on writing great answers most important formula in standard! 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