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Ch 3 Interaction Design Process. Yonglei Tao. Interaction Design. An iterative process through cycles of design-evaluation-redesign. User-Centered Design (UCD). Pioneered by Donald Norman’s research lab at UC San Diego A design framework for building usable systems Principles
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Ch 3 Interaction Design Process Yonglei Tao
Interaction Design • An iterative process • through cycles of design-evaluation-redesign
User-Centered Design (UCD) • Pioneered by Donald Norman’s research lab at UC San Diego • A design framework for building usable systems • Principles • Techniques
User-Centered Design (UCD) • Design should emerge from the user’s • Tasks – data, functions, and workflows • Goals • Environment • Focus on human-centric issues • Cognition • Perception • Physical attributes and conditions
Characteristics • Early focus on users and their tasks • Continuous evaluations to determine ease of learning and ease of use • Iterative design
User-Centered Design • Involving the following methods • User Participation • Focus Groups • Questionnaires • Observations • Walkthroughs • Expert Evaluations • Usability Testing
Interaction Design Models • Waterfall Model • Spiral Model • Dynamic Systems Development Method • Prototype-Based Models • Discount Usability Engineering • Contextual Inquiry
Discount Usability Engineering • Proposed by Jakob Nielsen • Basic ideas • Changes in user interface design are substantial in the early stages of development • No need to use comprehensive prototyping and usability testing techniques • Benefits derived from even small amounts of user testing would have a significant impact on the usability of the design • So “test early and often”
User Testing • Problems that can be identified from a usability test with n users can be described as follows
Basic Techniques • Scenarios • Paper prototyping on the basis of scenarios • Thinking aloud • Involve 3 to 6 users for usability testing • Ask them to think out loud when performing given tasks • Collect data by note-taking • Heuristic evaluation • Evaluate according to established usability principles • Involve a few reviewers to avoid personal bias • Do early in the design process
Cost Savings in a Medium Project • Source - http://www.nngroup.com/articles/guerrilla-hci/
How Many Users in a Usability Test? • Test five users (Jakob Nielsen, 2012) • Allowing you to find almost as many usability problems as you would find using many more test users • Sufficient to collect insights to drive your design • There are exceptions • Quantitative studies – test at least 20 users • Card sorting – test at least 15 users • Eyetracking – test 39 users for stable heatmaps • A small number of test users are more cost effective • More tests, not more users in each test
83 Case Studies by Norman Group • Source - http://www.nngroup.com/articles/how-many-test-users/