The general principles of the user interface can be given as follows:
- A design is aesthetically pleasing if it is attractive to the eye.It draws attention subliminally,conveying a message clearly & quickly.
- Visual appeal is provided by following the presentation & graphic design principles which include meaningful contrast between screen elements,creating spatial groupings,aligning screen elements,providing three-dimensional representation,& using color & graphics effectively.
- User interface must be clear in visual appearance,concept & wording.
- Visual elements should be understandable & related to real world concepts & functions.Analogies should be simple.
- Interface words & text should be simple,unambiguous,& free of computer jargon.
Compatibility needs to be provided as
- User Compatibility:“Know the user” is the fundamental principle in interface design as no users are alike & they think, feel & behave differently compared to the developer.
- Task & job compatibility:The structure & flow of functions should permit easy transition between tasks.The user must never be forced to navigate between applications or many screens to complete routine daily tasks.
- Product compatibility:compatibility across products must always be considered in relation to improving interfaces, making new systems compatible with existing systems will take advantage of what users already know & reduce the necessity for new learning.
- The steps to complete a task should be obvious.System should be understandable & flowing in meaningful order.
- A user should know what to look at,what to do,when to do it,where to do it,why to do it & how to do it.
- A default configuration as well as easy personalization & customization through configuration and reconfiguration should be provided.
- Customization enhances sense of control,encourages an active role in understanding & allows personal preferences & differences in experience levels leading to high user satisfaction.
- Consistency is important because it can reduce requirements for human learning by allowing skills learned in one situation to be transferred to another like it.
- Any new system must impose some learning requirements on its uses but avoid unnecessary activity.
- The user must control the interaction & never be interrupted for errors.
- Actions should result from explicit user requests & be performed quickly.
- Tasks should be performed directly & alternatives should be visible reducing the user’s mental workload.
- Tasks are performed by directly selecting an object then selecting an action performed & then seeing the action being performed.
- Transition between various systems controls should flow easily & freely.
- Navigation paths should be as short as possible.
- Eye movement through a screen should be obvious & sequential.
- Build into the interface concepts,terminology,workflows & spatial arrangements already familiar to the user.
- Familiar concepts enable people to get started & become productive quickly.
- Flexibility is the system’s ability to respond to individual differences in people.
- permitting system customization.
- People will make mistakes;a system should be able to tolerate those that are common & unavoidable.
- A forgiving system keeps people out of trouble.
- All actions should lead to results the user expects.Current operations should provide clues as to what will come next.
- Design consistency enhances predictability.
- A person should be able to retract any action by issuing an undo command.
- The goal is stability or returning easily to the right track when a wrong track has been taken.
- Recovery should be obvious,automatic,easy & natural to perform.
- A user must be responded quickly.
- Substantial or more informative feedback is most important for the casual or new system user.
- All requests must be acknowledged in some way.
- Simplicity can be achieved by progressive disclosure, provide defaults, minimize screen alignment points, make common actions points,make common actions simpler,& provide uniformity & consistency.
- Permit the user to focus on the task or job without concerning the mechanics of the interface.
- Working & reminders of workings inside the computer should be invisible to the user.
- Final design will be based on a series of trade-offs balancing often-conflicting design principles.
- People’s requirements always take precedence over technical requirements.