Users Perform Tasks, Not Features | Developing User Interfaces for Microsoft Windows

Users perform tasks. Programs provide features. That's a problem. Since users perform tasks but programs provide features, users often cannot do what they want to do directly. Rather, they have to understand the program's user interface enough to translate the task into a sequence of steps to take using the features provided by the program. This translation can be difficult, or it can be easy. The easier this translation, the easier the program is to understand and use. The harder the translation, the more the user has to learn. Your job as a user interface designer is to make this translation easy.

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Your job as a user interface designer is to make the translation from tasks to program features easy.

Levels of Learnability

There are several levels of learnability, from the case in which the user interface provides no clue at all about a feature to that in which the user interface provides everything the user needs to perform a task. These levels of learnability, starting with the most difficult case for the user, include the following:

A feature A feature exists. The user needs to learn about the feature's existence and functionality from a source external to the program, such as online help, printed documentation, or a coworker. A typical example is any MS-DOS command.

A visual feature A feature exists and is displayed visually on the screen, but its meaning and functionality are unclear. The user needs to learn about the feature's functionality from a source external to the program. A typical example is an indecipherable toolbar icon that doesn't have a helpful tooltip.

A visible feature A feature's existence and functionality are obvious by simple inspection. However, its functionality might not be obvious as a result of the visual properties of the object but because of standards or convention instead. For example, a feature implemented with a hyperlink is visible because its existence and functionality are obvious by inspection but only if you already understand hyperlinks.

A feature with affordance A feature's existence and functionality are obvious by simple inspection. Its visual properties suggest how it is to be used, so the user can figure it out without knowing any standards or conventions. For example, a command button has a raised 3-D border that makes it look like it can be pushed. As with this example, the interpretation of affordance is often dependent upon real-world experience. Such a feature could also be described as an intuitive feature.

A visible task The steps required to perform a task are obvious by simple inspection. The user interface makes it clear how to combine all the features required to perform a task. This ultimate level of learnability can be achieved by using a good conceptual model and natural mapping to combine visible features.

Visible user interfaces are the fundamental building blocks of good user interface design, and I have stressed this point in several chapters, including Chapter 10, "Good User Interfaces Are Visible" But although good user interfaces have visible features, the best user interfaces have visible tasks.

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The ultimate user interface design goal is to create visible tasks.