The term “cognitive load” was originally coined by psychologists to describe the mental effort required to learn new information. In terms of UX design, cognitive load is the amount of mental effort required to operate the UI system. Cognitive overload occurs when that effort exceeds a user’s ability to process information and keep track of their goals. When the amount of information users are presented is greater than their ability to process it, the user experience suffers.
Issues of cognitive load are connected to working memory, which is a cognitive system that allows us to simultaneously store and process current information. Working memory tends to accommodate between five and nine blocks of information at any given moment. The information that our brain processes gets put into categories in our working memory, where it’s then placed into our long-term memory and stored for later retrieval. The key, then, is to avoid overloading the user’s working memory with extraneous information.
Avoiding cognitive overload, however, requires more than simply reducing the amount of information for users to process at any given moment. The amount of time and number of actions needed between a user’s starting point and their destination should always be minimized. However, reducing the number of options available in service of avoiding cognitive overload could result in a large gap between a user’s present situation and their desired goal. When that gap grows too large, it can also lead to overloading users’ working memory.
Minimizing cognitive load in UI design can be achieved through a variety of means:
- Utilizing existing mental models for UI design will eliminate some of what is required of the user’s working memory since it builds on how users already believe the UI system will work
- Reducing visual clutter such as unnecessary images, excessive text, and ornate typography that gives users more information to process without adding anything of value
- Create a clear visual hierarchy that instinctually guides the user to what is most important, in essence doing some of the thinking and processing for them
- Take advantage of the “F-pattern” way of how people scan information and text on screens and monitors, placing more important information in certain sections of the UI to help guarantee it will be seen
- Stick to established icons to represent common features; a Home button should always look like a tiny home, email should resemble an envelope, and the “X” symbol should always mean ‘close’
The lower the cognitive load, the more intuitive the interface feels. The more intuitive the interface, the easier it becomes for users to accomplish their tasks. If the UI design doesn’t tax the user’s working memory, a far more fulfilling user experience will result.