Provide Rapid Response Make your application respond to input as rapidly as possible. The immediacy of the visual response is crucial to the experience of direct manipulation. When using components, provide the application's response immediately and in proportion to the component's actions. The application must also have a consistent speed of response. Delays, disproportionate responses, or inconsistent responses can render an otherwise well-designed application unusable.
Performance problems make it difficult for the user to concentrate on the task at hand.
Provide Output as Input Another feature of direct manipulation is that the output of one part of an application or the output of the application itself is also available as input. For example, if one action produces a list of filenames, another action can select them for use elsewhere. The user manipulates objects by locating them and clicking on them rather than typing in their names. Design so that the only time the user needs to type a name is to create an object. A well-designed application reduces the amount of information the user needs to memorize to perform tasks.