Published 19 Sep 2016
Cognitive load is the mental effort required to do something. This is a finite resource and a UI should therefore (in most cases) strive to reduce the cognitive load demanded by the user.
By following these principles, you can drastically reduce the user’s cognitive load and ensure their attention isn’t being wasted on elements that do not help them. It is important to remember that the user has a goal, whether it is to buy a product, understand something or simply to learn more about the content. The less they have to think about what they need to do to achieve their goal, the more likely it is they will achieve it.
Like everything in design, less is more. Any element that isn’t helping the user achieve their goal is working against them because they must process it and store it in working memory, alongside the things that will help them. Avoiding excessive colors, imagery, design flourishes, or layouts that don’t add value is crucial. But simplicity comes with a caveat: don’t overvalue it at the cost of clarity.
By leveraging common design patterns when it makes sense, you are giving the user familiar elements which they already understand. This in turn reduces the amount of learning they need to do, thus enabling them to move right along and get closer to achieving their goal.
Anywhere you are asking the user to read content, remember information or make a decision contributes to cognitive load. Whenever possible, it is good to shift these tasks away from the user and make it easier for them to stay focused on their goal. While it isn’t possible to remove all tasks, there is usually an opportunity to offload some task by setting defaults that can be edited, or leveraging previously entered information. Some companies are even taking this a step further with anticipatory design.
As previously mentioned, our working memory is limited. When confronted with too many choices, cognitive load will increase due to decision paralysis. It is important that we minimize the choices the user must make at any given moment, especially in places such as navigation, forms, and drop-downs.
When choices are split into separate groups and hidden, users often mistake the options that are visible as the complete group. This means that users are likely to never find the additional choices, which not only limits what is available to them, but also makes it more difficult to decide on which option to select because they are not aware of the alternatives. Therefore, it is best to eliminate the resulting cognitive load by always displaying choices as a group.
Making our content legible isn’t enough — we need to make it readable. This means our typography must be aesthetically pleasing, appropriate for the content and easy to read while design remains relatively invisible. By doing this, we can ensure there are as little distractions as possible for the user, which results in a better understanding of the content by the user.
Research has shown that iconography can be hard to memorize and, contrary to intuition, can increase cognitive load by requiring mental processing to infer meaning or recognize. While universally understood icons work well (ie. print, close, play/pause, reply, tweet, share on Facebook), most are subject to the user’s understanding based on previous experience (in which there is no standard). When leveraging the power of iconography, it is best to accompany them with text labels to communicate the meaning and reduce ambiguity.