User in Control

The user should always feel in control of the interface rather than feeling controlled by it. This principle has a number of implications:

• The operational assumption is that the user - not the interface - initiates actions. The user plays an active rather than reactive role. You can automate tasks, but implement the automation in a way that allows the user to choose or control it.
• The interface should be as interactive and responsive as possible. Avoid modes whenever possible. A mode is a state that excludes general interaction or otherwise limits the user to specific interactions. When a mode is the best or only design alternative - for example, for selecting a particular hardware function - make sure the mode is obvious, visible, the result of an explicit user choice, and easy to cancel.