Laws of UX The Laws of UX outline the best practices that designers use when creating user interfaces.
In 1954, psychologist Paul Fitts studied the human motor system and discovered that the time people take to move toward a target depends on the distance to it and the target’s size. He demonstrated that faster movements and smaller targets increase error rates because of the speed-accuracy trade-off. Although several versions of Fitts’ Law exist, they all share this core concept.
Designers widely apply Fitts’ Law in user experience (UX) and user interface (UI) design. For instance, designers make interactive buttons large, especially on touchscreens, because smaller buttons take more time and effort to click. They also reduce the distance between a user’s main focus area and the related action button to make interactions faster.
Fitts’ Law applies to rapid pointing movements—not continuous motions like drawing. These movements usually involve one large motion (called a ballistic movement) followed by small adjustments to accurately reach the target. In visual interface design, designers use this law to determine the right sizes for interactive elements and to identify potential usability issues.
Designers who follow Fitts’ Law create faster, more efficient interactions. For example, the right-click pop-up menu became popular because it reduces the distance users travel with their mouse to select an option, thereby saving time and improving productivity. In contrast, long drop-downs or title menus slow users down and make navigation less efficient.
What is Fitts’ Law?
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. Thus, the longer the distance and the smaller the target’s size, the longer it takes.
In 1954, psychologist Paul Fitts, examining the human motor system, showed that the time required to move to a target depends on the distance to it yet relates inversely to its size. By his law, fast movements and small targets result in greater error rates, due to the speed-accuracy trade-off. Although multiple variants of Fitts’ law exist, all encompass this idea.
Fitts’ law is widely applied in user experience (UX) and user interface (UI) design. For example, this law influenced the convention of making interactive buttons large (especially on finger-operated mobile devices)—smaller buttons are more difficult (and time-consuming) to click. Likewise, the distance between a user’s task/attention area and the task-related button should be kept as short as possible.
Such movements typically consist of one large motion component (ballistic movement) followed by fine adjustments to acquire (move over) the target. The law is particularly important in visual interface design—or any interface involving pointing (by finger or mouse, etc.): we use it to assess the appropriate sizes of interactive elements according to the context of use and highlight potential design usability problems.
Hick’s Law
The time it takes to make a decision increases with the number and complexity of choices.
Takeaways
- Minimize choices when response times are critical to decrease decision time.
- Break complex tasks into smaller steps in order to decrease cognitive load.
- Avoid overwhelming users by highlighting recommended options.
- Use progressive onboarding to minimize cognitive load for new users.
- Be careful not to simplify to the point of abstraction.
Google keeps the decisions required to enter a keyword to a minimum by eliminating any additional content that could distract from the act of typing a keyword or require additional decision-making.
Apple TV Remote
Apple TV remotes don’t require a substantial amount of working memory and therefore incur much less cognitive load. By transferring complexity to the TV interface itself, information can be effectively organized and progressively disclosed within menus.
Slack’s Progressive Onboarding
Instead of dropping users into a fully featured app after enduring a few onboarding slides, Slack uses a bot to engage users and prompt them to learn the messaging feature consequence-free. To prevent new users from feeling overwhelmed, Slack hides all features except for the messaging input. Once users have learned how to message via Slackbot, they are progressively introduced to additional features.
Origins
Hick’s Law (or the Hick-Hyman Law) is named after a British and an American psychologist team of William Edmund Hick and Ray Hyman. In 1952, this pair set out to examine the relationship between the number of stimuli present and an individual’s reaction time to any given stimulus. As you would expect, the more stimuli to choose from, the longer it takes the user to make a decision on which one to interact with. Users bombarded with choices have to take time to interpret and decide, giving them work they don’t want.
Jakob’s Law
Jakob’s Law says users expect new products to work like ones they already use.
Familiar design elements, like buttons and toggles, help users understand interfaces easily.
When YouTube redesigned its site in 2017, it let users preview and switch back to the old version, reducing confusion.
Jakob Nielsen, co-founder of the Nielsen Norman Group, created this law to promote simple and user-friendly design.