Allow Direct Manipulation Users need to be able to directly manipulate elements of the user interface and their applications. For example, the user needs to be able to directly scroll Text with a ScrollBar , rather than using a keyboard-driven command. Direct manipulation simulates the real world where the user employs tools to perform tasks on physical objects. Users control applications by directly manipulating graphical components similar to real-world controls, rather than entering a command on a command line. Direct manipulation reduces the amount of information the user needs to memorize.
Direct manipulation connects an action to an observable response from a component.
Using direct manipulation, the user gets an immediate visible result from each action. The direct manipulation model is an object-action model. That is, you first select an object or group of objects, then you perform an action on the selected objects. An object-action model allows the user to see what elements will be acted on before performing an action. It also allows multiple actions to be performed successively on the selected elements.