Usability testing of an interface design measures five basic factors. These are Learnability (how fast a user who has never seen a user interface design before learns to use it well enough to accomplish basic tasks); Efficiency (how fast a user can accomplish tasks after learning to use a user interface design); Memorability (After using a user interface design in the past, can users remember enough of the system to use it effectively or do they need to learn it all over again); Errors (how many errors do users make using an interface design, how severe are these errors, and how easily can users recover from them); and Subjective Satisfaction (how much does the user like using the interface design). In this article I shall focus on the learnability of an interface design .
What is learnability?
According to the Usability First glossary learnability is a measure of the degree to which a user interface design can be learned quickly and effectively. Learning time is the typical measure. User interface designs are typically easier to learn when they are designed to be easy to use based on core psychological properties, and when they are familiar. Familiarity may come from the fact that an interface design follows standards or that the interface design follows a metaphor from peoples’ real world experience. The learnability of an interface design can be, in turn, further broken down into five similar but distinct components: the aforementioned Familiarity, Consistency, Generalizability, Predictability, and Simplicity.
What part does familiarity play in the learnability of an interface design?
When optimizing a user interface design for learnability, familiarity comes into play because users tend to expect certain things to happen. An example of this is the expectation of where to find an application’s menu such as File, Edit, View or Help. Users will expect to find those at the top of an application, usually in a particular order with corresponding sub-menu options. This setup will also have to correspond with the operating system in use. Windows users will expect to always find minimize, maximize and close window buttons on the top right of a software application’s interface design whereas Mac users will expect them on the top right with the traffic lights color codes. When engendering the familiarity of an interface design one has to keep in mind all users, resorting to the lowest common denominator. Usability testing with participants who are not developers or power users is key in uncovering any usability issues.
What part does consistency play in the learnability of an interface design?
Beyond the expectation of familiarity in an interface design, extra attention needs to be paid to maintaining consistency. Although familiarity itself also calls for consistency, consistency must also be maintained within the different parts of a software application’s interface design. Your application has to react in the same way throughout. An example of this is with the login process. The login and sign up buttons should be consistently displayed throughout your website’s interface design i.e. if it is found on the top right corner then so should it remain throughout. Consistency becomes more of a challenge with applications that allow users to change skins or customize the interface design. A skin that requires users to relearn how to use an interface design is likely to turn off users.