7.2.4-1 Appropriate Use of Discrete-Adjustment Interfaces

Discrete-adjustment interfaces should be used for selecting among a set of individual settings or values.

Additional Information:
Discrete-adjustment interfaces are computer-based formats with individual settings that can be accessed by fairly gross movements; their operation is similar to discrete-adjustment controls, such as push buttons. By contrast, continuous-adjustment interfaces are computer-based formats that have continuous ranges usually accessed using some type of slewing motion, requiring a gross movement followed by a fine adjustment; their operation is similar to that of continuous-adjustment controls, such as rotary dials or sliders. Discrete-adjustment interfaces are preferred when the user must select one option from a limited number of choices, or when precision requirements are such that a limited number of settings can represent the entire continuum of values. The most common discrete- adjustment interfaces used with soft controls are individual buttons and radio buttons (a group of buttons representing a set of related options). However, other formats also are possible, such as rotary selector dials operated via cursor or gestural interfaces. Some computer interfaces have a continuous-adjustment control, such as a slider or scroll bar, for looking at a group of individual options. Because choosing a specific setting with a continuous-adjustment control can be awkward, there should also be a discrete- adjustment control, such as a set of arrow buttons.