User Center Design (UCD)

3 Constraints to Design : Task - Human - Technology

Usability Criteria

• Ease of learning: learning cost / use of advanced functionalities
• Recall: Remember how from one session to the next
• Productivity: speed of execution
• Fatigue (cf. repetitive actions)
• Risk of errors: should be minimized, good feebcak needed otherwise
• User satisfaction
  Accessibility, functionality, time, effort, learnability, satisfaction, …

Ideation

Brainstorm, Sketches….

Prototype

Methods: • Storyboards — good for user flow • Paper prototypes — good for layout, flow • Video prototypes — good for overall experience • Powerpoint/Photoshop — Look ’n’ feel • Software — functionality

Evaluation

Methods:

With users • Logs
• Questionnaires
• Open-ended vs. Closed
• Observation
• In-the-wild vs. in the lab (ecological validity)
• Think-Aloud • Controlled Experiments

Ecological validity — users; tasks; context ?

Predictive(without users)
• Cognitive Models • Heuristic Evaluation • Cognitive Walkthrough