REVISION AND PRACTICE
Week 3 — Quick Revision
- Interaction design cycle: Identify needs and requirements → Develop alternative designs → Build interactive versions → Evaluate.
- Usability (ISO 9241-11): The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.
- Usability goals: Effectiveness, Efficiency, Safety, Learnability, Memorability.
- User experience goals: positive, subjective — satisfying, enjoyable, fun, helpful, entertaining, motivating, emotionally fulfilling.
- Learnability for complex tasks: Wizards, Tours, Templates.
- Safety: Therac-25 — the operator pressed X (X-ray mode) instead of E (electron mode); excess radiation led to the death of a patient. Save and Close buttons are placed far apart to prevent unwanted actions.
- Memorability: meaningful icons, command names and menu options in Microsoft Word help returning users remember where tools are.
- Storyboard = Setting + Sequence + Satisfaction.
- Storyboard benefits: Emphasizes how the interface accomplishes a task (without specific details); avoids commitment to a particular user interface (the storyboard communicates the task without implementing the application or committing to a detailed UI); shared understanding among stakeholders.
- Paper prototype: a hand-drawn interface using multiple pieces of paper for different screens. Benefits: Easier than writing code for the UI; starts conversations about user interactions; elements can be changed immediately based on feedback.
- Prototypes facilitate conversations: storyboards → user tasks; paper prototypes → user interactions; digital mock-ups → visual design; interactive prototypes → picky usability details.
- Heuristics are adapted from Jakob Nielsen and grouped by Scott Klemmer into Understanding, Action and Feedback.
- Understanding = consistency, familiar language and metaphors, clean and functional design. Action = freedom, flexibility, recognition over recall. Feedback = show status, prevent errors, support error recovery, provide help.
- Error recovery: make the problem clear / provide a solution / provide an alternative.
- Heuristic evaluation: experts do multiple passes through initial prototypes and list design-heuristic violations; feedback from several experts helps fix usability issues. Heuristics are also a self-check for designers.