 Welcome to User Experience Design, Fitts' Law. This learning module provides an introduction to Fitts' Law and explains how it's applied to user experience design. Let's start with, what is Fitts' Law? To be honest, Fitts' Law isn't really a law at all. It's actually a descriptive model of human psychomotor behavior that's written as an equation, like this one. In the formula, MT is the average time to complete the movement. A and B are model parameters. D is the distance of movement from start to target center. W is the width of the target. Fitts' Law is a model of human movement. It tracks the time it takes to point at something, taking into consideration the size and distance of the target. So far, this seems super confusing. However, Fitts' Law is easy to understand. Fundamentally, it proves that it's faster for you to hit larger targets that are closer to you than it is to hit smaller targets that are farther away from you. If you look at the keys on your computer keyboard, you'll notice that the keys users press most often. The enter key, the space bar, and the shift key are larger than the other modifying keys. These keys are larger so they're easier to hit. They're also closer to the alphanumeric keys. Keys that are used less often, like insert, delete, and escape, are farther away from the alphanumeric keys. User experience designers use Fitts' Law when creating user interfaces. Good UX designers ensure that any time they want users to interact with the software or the interface, they make it obvious. Targets are easily located and easy to use. UX designers also know that the farther away a user's mouse is and the smaller the on-screen target is, the longer it takes someone to move the cursor and click on the target. We know that the size of the target matters. The larger the target, the easier it is to hit. This might lead a designer to think that the bigger buttons are always better. However, that isn't always the case. Fitts' Law is a curve, which means that smaller objects are easier to click if they're made larger. However, larger objects are already large, so if they're made larger yet, they aren't any easier to click. Because of this curve, the benefits of increased size begin to decrease. This is actually good news for designers because it frees up more on-screen real estate and ensures on-screen objects are appropriately sized for their intended use. Good on-screen target placement is critical. As a UX designer, the physical locations of your screen elements are important. The Gutenberg diagram shows that users tend to move through screens from top left to bottom right. Therefore, consider placing what's important, like the buttons that call users to action, in the bottom right-hand corner. When designing an on-screen layout, ask yourself if your critical icons are the ones users are most likely to use. Are they on the path that your user's cursor takes? Remember to apply Fitts' Law to your design principles. When designing graphics, text, and screen icons, always consider their sizes. Are they appropriately sized for their intended use? Consider making any text labels into links. Try making the whole phrase a link rather than just one word. On the WISC Online website, the entire phrase Switch to WTCS Categories is a link instead of just Categories or WTCS. This makes the target bigger and easier for the user to hit. Keep in mind the devices that your customers are using. If you're developing a touchscreen interface, ask yourself, are the elements big enough and spaced properly to allow your user to pick just one? The spacing between on-screen elements is just as important as the size of the elements. Remember Fitts' Law. It's faster to hit larger targets closer to you than it is to hit smaller targets farther from you. You have completed User Experience Design, Fitts' Law.