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CSC111H User Interface Design

Dennis Burford

dburford@cs.uct.ac.za

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Why and What?

• Why bother with the design of user interfaces?

• What makes a “good” user interface?

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Designing for Users

• Software is useless if users can’t use it

• Design for users!

• Basis of user interface design should be to allow user to achieve their goals.– look at tasks which user is trying to achieve– look at user’s capabilities

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Chat Program

• What are your user’s goals and tasks?

• How can you make it easier to achieve these?

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Examples of Bad Interfaces….

• What is wrong with these interfaces?

• Why is it a problem?

• What are you supposed to do? What is the sequence of actions?

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In general...

• Don’t force user to accept bad interface because it is easy to implement!

• Don’t just add stuff because you can

• KISS: Keep it simple stupid

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Some Design Principles

• Based on Human capabilities

• Physical and mental limitations of people using system

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Human Capabilities

Memory (7 ± 2 things)• Avoid clutter (Economy)• Avoid Cognitive Overload• Consistency

Affordances• User familiarity• Past Experience• Match interface to

user group• Intuitive display of

status, info and controls

Direct Manipulation

No Surprises

Mistakes• Confirmation• Recoverability

Perception andVisual Recognition

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Affordances

• Visual representation of world of action

• Devices “afford’ usage…– e.g. door handles, knife-fork-spoon, pen,

scissors

• GUIs: scrollbars, sliders, buttons, dials

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Direct Manipulation

• Show objects of interest

• Actions – Rapidly executed

– Performable incrementally

– Reversible

• Show results of actions immediately

(E.g. Colour Chooser)

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Direct Manipulation

While task incomplete:1. Observe

2. Take Action

3. Get Feedback

4. Adjust Mental Model

Ensure each step (and whole process) is “natural” / intuitive

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Information Presentation

• Obvious and Intuitive – real world analogies– e.g. Dial, temperature gauge, progress bar

• Color and Layout

• Avoid Clutter

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Evaluation

• Part of testing

• Can the users perform their task– successfully– efficiently

• Learnability, speed of operation, robustness, recoverability, adaptability