Principles to Support Usability

Get introduced to the principles that support the usability of a system.

We'll cover the following

Being a designer, how will you know whether the design you created is usable by the user or not? In order to determine the usability of our design, we need design rules and principles. All possible principles that can support usability are roughly divided into three main categories: learnability, flexibility, and robustness.


Learnability principles determine how easily novice users can learn to interact with system features and attain maximum expertise. Here are a few key things to remember to improve learnability.

  • Predictability
    The user should be able to predict the results of future actions based on the knowledge of their interaction history. Predictability can be satisfied with multiple degrees. For example, it can be achieved by:

    • Restricting the required user’s knowledge to currently perceivable information.
    • Increasing the required user’s knowledge to every previous action and every previous display’s content.

    Operation visibility is a form of predictability concerned with showing the users all available operations they can perform next. If all operations are visible, the user will be able to consider all possible actions that could be performed.

  • Synthesizability
    The user should be able to perceive the effects of actions on the system interface, i.e. the updated system must be reflected on the interface. The interface’s ability to reflect system state changes is called honesty. There are two aspects of synthesizability:

    • Immediate honesty: Notifying the user without requiring any further action from the user. For example, when moving a file from one folder to another using WIMP interaction styles, the user can see the file moving. After it has moved, the user can immediately see the file in the destination folder.
    • Eventual honesty: Notifying the users after they have performed the required actions. For example, when moving a file from one folder to another using command-line interaction styles, the system state does not update the user on what percent of the file has been moved. Once the file has moved, the user has to recall the destination folder address and run a command to list folder content in order to check if the file is present in the new position.

Get hands-on with 1200+ tech skills courses.