User Interface Design

Principles of Good Design

• State and action alternatives are visible
• Conceptual model is consistent with system image
• Interface should include mappings that reveal relationships among stages
• User should receive continuous feedback

Where failure is likely as users try to accomplish goals?

• Users form inadequate goals
• Users fail to find the correct interface object due to poor labeling
• Users might not know how to specify or execute a desired action
• Users receive poor feedback

Building novel widgets that match user task perceptions

• Recognize human diversity
• Use 8 golden rules of user interface design
• Prevent errors

Golden Rules of User Interface Design

• Strive for consistency
• Enable short-cuts for frequent users
• Informative feedback
• Design dialogs to yield closure
• Offer simple error handling
• Permit easy reversal of actions
• Support internal locus of control
• Reduce short-term memory load on user

Data Display Guidelines

• Consistency
• Efficient information assimilation by user
• Minimal memory load on user
• Compatibility between data display and data entry
• Flexibility of user control over data display

Getting Operators Attention

• Intensity (2 levels only)
• Marking (e.g. underscore)
• Fonts (up to 3)
• Inverse video
• Blinking (2 to 4 hertz)
• Color (up to 4 standard colors)
• Color blinking
• Audio

Data Entry Guidelines

• Consistency
• Minimal user input actions
• Minimal memory load on user
• Compatibility between data entry and data display
• Flexible user control