Fitts’s Law, often called Fitts’ Law, is actually a predictive model regarding human movement. It was created by Paul Fitts in 1954! This model is believed to predict accurately the amount of time taken by any human to move and to select a target. This model was originally developed based on the movement in the physical world.
However, when it comes to the relation of a human with the computer and the interaction between them and the ergonomics, Fitts’s Law is applied typically to ascertain the movement through the graphical user interface by using the cursor or any other type of pointer.
- This scientific law predicts such movement as a ratio between the width of the target and the distance to it.
- This law has been formulated mathematically in a large number of ways, but it is found that the predictions it provides, regardless of the ways, are consistent across any given mathematical representations.
If you put Fitts’s Law in simple words, it is actually the time taken by a human to acquire a target. Since this is primarily based on the distance to and the size of the target, this law actually represents different factors apart from the time taken.
- It says that movement will take longer if the distance of the target increases.
- It also says that selection will also take a longer time if the size of the target decreases.
Now, you may wonder about the time when this law was actually formulated by Paul Fitts. 1954! As a modern UX designer in NYC, you may wonder how this law is applicable to modern UX designs if the law itself was designed at a time when there was no such thing such as graphical user interfaces. Well, that is the magic and robustness of this law, which holds true even today when it is applied to navigation in this virtual world!
Application of Fitts’s Law
When it comes to user interface design, Fitts’s law is applied most importantly to consider the size and distance of the UI design. This helps the designers to ensure a better user experience.
This is because the user experience is affected in a number of ways, but it is mostly affected by the size of the target and its distance from the current position of the user within the user interface.
The use and application of this law helps the designers to know and consider the major implications for user interface and design the product accordingly to ensure better user experience. A few of such major implications can be summarized as follows:
- The command buttons, as well as any other collaborative elements in the graphical user interface, must be eminent from all those non-interactive elements in it by their size. This may seem to be a very obvious fact, but it is found that during user interface design, this aspect is often ignored. It is clear and evident that the larger the command button is, the easier it is to click on it, regardless of the type of pointer and pointing device used. When the size of interactive objects is decreased, it reduces the surface area consequently and, as a result, the users require a higher level of precision to click on, it thereby increasing the selection times.
- The corners and outer edges are the next things that you should consider in the graphical user interface. Due to the sticking action of the screen, these can be attained with superior speed than anywhere else in the display. The pointing device is unable to move any further simply due to the fact that the users are constrained in their movements when they reach the farthest points of the screen. That means this will fix the cursor at a specific point within the periphery of the display.
- Consider the pop-up menus next, which offer better support when it comes to the immediate selection requirements of the interactive elements. These are even better in efficiency and action as compared with the dropdown menus. This is because the user usually does not require moving the cursor or the pointer from the current position. This will eventually reduce the travel time of the users as they will be able to interact without moving.
- There are several linear menus as selecting options available in the user interface that may be vertical, like the dropdown menus, or horizontal, like the ones in the top-level navigation bar. These menus ideally take a longer time to click as compared to the pie menus, wherein all the options are available and arranged in a circle. That means the traveling distance is typically the same for all the available options in the pie menus, much unlike the linear menus, wherein the time increases when the distance increases further when the user has to move along or down the menu list of options. In addition to that, the size of the target areas is also larger in the pie menu as compared with any other menu, which once again reduces the time. This is because the wedge-shaped navigation buttons can afford a larger margin for error while the user moves the cursor.
- The taskbar is another useful component of the user interface that hinders movement through the interface. This is because these usually require more precision as well as more time to navigate as compared to the options that are placed on the exterior limits of the screen. Though there is no direct connection to Fitts’s Law, it is a fact that when there are numerous taskbars, it can present a definite level of misperception or, at the very least, necessitate the users to engage more consciously with the arrangement of the screen to ensure apposite selection.
Maintaining all these components in the user interface design is essential, but with Fitts’s law in place, it becomes easy due to prompt discovery and selection of the interactive foundations without needing to sacrifice accuracy. It will enable you to design according to the expectations of the users.