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Designing the User Interface

Designing the User Interface. Theories, Principles, and Guidelines Course 4, CMC , 23/09/03. Designing User Interfaces. “Designing user interfaces is a complex and highly creative process that blends intuition, experience, and careful consideration of numerous technical issues”

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Designing the User Interface

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  1. Designing the User Interface Theories, Principles, and Guidelines Course 4, CMC, 23/09/03

  2. Designing User Interfaces “Designing user interfaces is a complex and highly creative process that blends intuition, experience, and careful consideration of numerous technical issues” Ben Shneiderman (1998, 3rd ed.) HC4

  3. User Interface • Locus of interaction • Cushioning buffer • Visible aspect of the invisible system HC4

  4. Human-Machine Loop Display tells user machine’s state Perceptual system detects state Controls allow user to affect machine’s state Effector system operates controls HC4

  5. Goals of Interactive Systems • Simplifying user’s tasks • routine tasks • tedious tasks • error-prone tasks • Eliminating human actions when no judgment is required HC4

  6. Causes user’s frustration, fear and failure • Excessive complexity • Incomprehensible terminology • Chaotic layouts HC4

  7. High-quality interactive systems I • Beyond vague notion of “user friendliness” • Thoughtful planning • Sensitivity to user needs • Diligent testing HC4

  8. High-quality interactive systems II • Positive feelings of success, competence, mastery, clarity • Interface almost disappears • Interface is comprehensible and predictable • Interface masks underlying computational complexity • Users remain “in the flow” HC4

  9. Goals of system engineering • Adequate functionality (task analysis) • Reliability • Standardization • Schedule and budgetary planning HC4

  10. Goals of Interface Design • Design and testing of multiple alternatives • for specific user communities • for specific tasks • Measurable human factors • time to learn • speed of performance • rate of errors • retention over time • subjective satisfaction HC4

  11. Guidance for designers • High-level theories and models • Middle-level principles • Specific and practical guidelines HC4

  12. High-level theories I • Four-level approach of Foley & van Dam (1990): conceptual-semantic-syntactic-lexical • GOMS and the keystroke-level model Card, Moran& Newell (1980,1983); Kieras & Polson (1985); Kieras (1988); Elkerton & Palmiter (1991) HC4

  13. High-level theories II • Stages-of-actions models: Norman (1988)’s 7 stages of action • forming goal • forming intention • specifying action • executing action • perceiving system state • interpreting system state • evaluating outcome HC4

  14. High-level theories III • Consistency through action grammars: Reisner (1981); Payne & Green (1986) • task[Direction, Unit] -> symbol[Direction] + letter[Unit] • symbol[Direction=forward] -> “CTRL” • symbol[Direction=backward] -> “ESC” • letter[Unit=word] -> “W” • letter[Unit=character] -> “C” HC4

  15. High-level theories IV • Widget-level theories: Object-Action Interface Model of Shneiderman (1980, 1981, 1983) • Hierarchies of task objects and actions • Hierarchies of interface objects and actions • Metaphoric representation conveys interface objects and actions • Tuning of interface objects and actions to fit the task • Direct manipulation approach to design • Minimizing burdens of syntax HC4

  16. Middle-level Principles • Principle 1: recognize diversity • Principle 2: use the 8 golden rules of interface design • Principle 3: prevent errors HC4

  17. Recognize diversity I • Usage profiles • novice or first-time users • knowledgeable intermittent users • expert frequent users • Accommodation of one system to different usage classes • level-structured learning • user control of density of informative feedback HC4

  18. Recognize diversity II • Task Profiles • appropriate sets of atomic objects and actions • relative task frequencies • Primary Interaction Styles • direct manipulation • menu selection • form fillin • command language • natural language HC4

  19. 8 Golden Rules of Interface Design • Strive for consistency • Enable frequent users to use shortcuts • Offer 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 HC4

  20. Prevent Errors • Correct matching pairs • Complete sequences of actions • Correct commands • Direct manipulation strategies HC4

  21. Summary • Task analysis • “Know thy user” • Recording task objects and actions • Construction of suitable interface objects and actions • Extensive testing • Iterative refinement HC4

  22. Points to discuss • Faulkner, Raskin, Sutcliffe • Oulanov & Pajarillo • Usability Evaluation of OPC • Contribution of Communication and Information Science to HCI HC4

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