Specifications

6 | USER INTERFACE
DESIGN GUIDE
interaction. This can make an interface more complex and cumbersome. Minimal doesn’t mean small, but rather elegant and
simple, so be sure to maintain a proper sense of scale to preserve text legibility, the users’ context, and their sense of place
in the interface on the whole.
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.
Forgiveness
Users like to explore an interface and often learn by trial and error; however they expect to have immediate success with the
majority of attempted tasks. An effective interface allows for interactive discovery. It provides only appropriate sets of choices
and warns users about potential situations where they could damage the system or make global changes to the system.
Even in the best-designed interface, users can make mistakes. These mistakes can be both physical (accidentally pointing to
the wrong command or data) and mental (making a wrong decision about which command or data to select). An effective
interface avoids situations that are likely to result in errors. It also accommodates potential user errors and makes it easy for
the user to recover.
Feedback
Always provide feedback for a user’s actions. Good feedback helps confirm that the interface is responding to input and
communicates details that distinguish the nature of the action. Effective feedback is timely and is presented as close to
the point of the user’s interaction as possible. Even when the interface is processing a particular task, provide the user with