Designing for User Interaction

Feedback

Consider user interactions as part of an ongoing dialog between the user and the interface. Often, when people converse, the listener provides feedback to the user to indicate that the message is being received. Feedback is the application's return of a dialog (or other cue) to the user's input.

As in dialogs between people, users appreciate feedback in dialogs with the interface to help them understand what information the system has received. Therefore, design your interface to provide feedback that is subtle but consistent.

Also, provide transitions to help users follow the results of their interactions. Think of transitions as providing a “storytelling” aspect in the interface. In other words, use transitions to help users understand the flow from one step to the next. Transitions should be noticeable but subtle so that they are helpful to less experienced users and do not annoy experienced users.

An example of a subtle transition is graduated boxes (sometimes called zoom boxes or nested boxes) that appear when the user closes a window. They tell the user that the view has been closed and the data put away. If the window simply disappears, the user might think that the information had been deleted.

As with static elements, all the visual variables can play a role in communicating interaction cues and transitions, including size, shape, movement, and color. However, interactive cues and transitions can incorporate an additional important visual interface concept: movement. Users react instinctively to movement. For example, when a printer icon displays paper ejecting from the printer, the user knows that the print job was successfully spooled. Therefore, movement is one of the most powerful visual variables. To maintain that potency, use movement sparingly and only where absolutely necessary.

Cues

Unlike feedback, a cue may alert the user unexpectedly, for example, when a printer jam occurs.

Because graphical user interfaces are still mainly visual, visual cues are numerous. When designing a new visual cue or set of visual cues, avoid conflicts with preexisting cues. As with any type of cue, efficiency of a visual cue depends on its timing. Carefully choose when to display or remove a cue in relation to user action. You can intensify the effect of certain visual cues by combining them with appropriate audible cues.

For example, if a printer runs out of paper during printing, the audible cue attracts user attention while the blinking sheet of paper on the printer icon informs the user of the nature of the problem. The interface can indicate a paper jam by another visual cue, such as the paper on the printer icon changing color or shade.

For more information on cues, refer to Chapter 4 “Audible and Visual Interface Cues”