What are learnability principles for usability?

Usability is a quality of the user interface that refers to how easily and efficiently a user can perform a task using it. There are some principles that designers should incorporate into their design to maximize usability. These principles are divided into three broad categories:

• Learnability

• Flexibility

• Robustness

In this answer, we'll learn the learnability principles that support usability.

Learnability principles

Learnability pertains to how easy it is for new users to perform initial interactions and continue with utmost performance. The following principles fall under the category of learnability principles:

Predictability

The principle of predictability states that the user should be able to predict the future interaction based on their previous history with the interface. This means that the system should be deterministic from the user's perspective, as the user should be able to determine the effect of any actions, such as clicking a mouse button on the interface.

Another aspect of predictability allows the user to predict which operations can or can not be performed on the interface. This is known as operation visibility.

One way to incorporate predictability is by designing conventionally. For example, the magnifying glass icon is used standardly for search. When users see this icon in a new interface, they can predict based on their experience that it will be used for searching.

Synthesizability

Synthesizability refers to the interface allowing users to assess the effect of their actions on the system state. It deals with the principle of honesty, which states that the system should notify users about the result of their operation and any changes in the system state. This honesty is of two types:

• Immediate honesty: Ideally, the interface should immediately inform the user of any changes due to their action. This is observed in GUIsGraphical User Interface. For example, when a new folder is created on Windows, the user can immediately see a folder icon named "New Folder."

• Eventual honesty: This is when the user has to perform some actions to confirm the change. For example, in CLIsCommand Line Interface, when a new folder is created, the user has to remember the destination directory and verify the creation after running some commands.

Familiarity

The familiarity principle allows users to utilize prior knowledge to understand the interface's features. It deals with how easily users can begin the interaction based on their initial perception.

The most common example of familiarity is that of word processors. When word processors were first introduced, they were made to look similar to typewriters so users could easily perceive how to begin using them.

Familiarity is incorporated using affordancesRelating the usage of something with its appearance. and metaphors. For example, users will know that a 3D button on an interface should be pushed similarly to their real-life experience with buttons. Another example is the conventional use of the Recycle Bin to represent deleted items.

Generalizability

Generalizability means that users can apply their experience of specific interfaces to new, similar ones. It also refers to extending the knowledge of performing an action on one interface to a similar action on the same interface.

An example of generalizability across different interfaces is how the cut/paste operations are supported with the same shortcuts over numerous applications. As another example, generalizability is supported if a user knows how to draw a rectangle in a drawing application and can apply this knowledge to sketching a circle in the same application.

Consistency

Consistency means that the same input/output actions should perform the same functions with the same behavior. It also concerns the interface's appearance, where consistency can be incorporated using a pre-determined color palette.

Consistency should be present across applications and within the same application as well. For example, options on dialog boxes should have the exact placement throughout the application. Consistency across different applications is showcased in the consistent designs of MS Office products that help users predict their functions and learn faster.