The Golden rule
These golden rules actually form the basis for a set of user interface design principles that guide this important software design activity.
1 Place the User in control
Most interface constraints and restriction that are imposed by a designer are intended to simplify the mode of interaction. The designer might introduce constraints and limitations to simplify the implementation of the interface. The result may be an interface that is easy to build, but frustrating to use.
- Define interaction modes in a way that does not face a user into unnecessary or undesired actions.
- Provide for flexible interaction
- Allow user interaction to be interruptible and undoable.
- Streamline interaction as skill levels advance and allow the interaction to be customized.
- Hide technical internals from the casual user.
- Design for direct interaction with objects that appear on the screen.
2 Reduce the User’s Memory Load
A well designed user interface does not tax the user’s memory. Whenever possible, the system should “remember” pertinent information and assist the user with an interaction scenario that assists recall.
Design principles to reduce the user’s memory load:
- Reduce demand on short-term memory. The interface should be designed to reduce the requirements to remember past actions and results. This can be accomplished by providing visual cues that enable a user to recognize past actions, rather than having to recall them.
- Establish meaningful defaults.
- Define shortcuts that are intuitive.
- The visual layout of the interface should be based on a real world metaphor.
- Disclose information in a progressive fashion.
3 Make the Interface consistent
The interface should present and acquire information in a consistent fashion. This implies that
- all visual information is organized according to a design standard that is maintained throughout all screen displays,
- input mechanisms are constrained to a limited set that are used consistently throughout the application, and
- mechanism for navigating from task to task are consistently defined and implemented.
Design principles to Make the Interface consistent:
- Allow the user to put the current task into a meaningful context. It’s important to provide indicators that enable the user to know the context of the work at hand.
- Maintain consistency across a family of applications. A set of applications should all implement the same design rules so that consistency is maintained for all interaction.
- If past interactive models have created user expectation, do not make changes unless there is a compelling reason to do so.