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Design Rules-Part B Standards and Guidelines

Design Rules-Part B Standards and Guidelines

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Design Rules-Part B Standards and Guidelines

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  1. Design Rules-Part BStandards and Guidelines Material from Authors of Human Computer Interaction Alan Dix, et al

  2. Overview • Design rules in the form of standards and guideline to provide direction • Essential characteristics of good design • Design patterns for a generative approach to capture/reuse design knowledge

  3. Standards • Usually set by national & international bodies • Apply to HW and SW in interactive systems • Different characteristics of HW & SW affect utility of design • underlying theory • HW – physiology or ergonomics • SW – psychology or cognitive science (more vague) • change • HW – difficult/expensive to change • SW – flexible

  4. ISO Standard 9241 Example • Pertains to usability specification and applies to HW and SW design • Defines usability as • The effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments • Goes on to define effectiveness, efficiency and satisfaction • Definitions important as they give us ideas of how to measure usability.

  5. Strength of Standards • Lies in ability to force large communities to abide (so-called authority) • Most standards are suggestions • Some practices become de facto standards before formalization

  6. Guidelines • Not rules, suggestions • The more abstract the guideline, the more it resembles a principle outlined in 7.2 • The more specific, the more suited it is to detailed design • Even more useful, if they can be automated to translate detailed design into implementation

  7. Guidelines for Interactive Design • …or interface design • Smith and Mosier (Mitre) 6 basic categories • data entry, data display, sequence control, user guidance, data transmission, data protection • broken into more specific subcategories • Example: Data Entry position designation distinctive cursor – movable, visual feature (shape, blink, etc.) : See also 1.1-17 Distinctive multiple cursors • allows cross-referencing

  8. Guidelines for Interactive Design • Mayhew • more recent, comprehensive, general guidelines in a catalog

  9. Guidelines • Dialog styles • question and answer, form-filling, menu selection, function keys, command language, query, natural language, direct manipulation • Most guidelines applicable for implementation of any one of dialog styles in isolation • Must also consider mixing of styles in an application (Mayhew provides guidelines on this)

  10. Specific Guidelines • Apple’s HCI Guidelines: the Apple Desktop Interface • Abstract principle in Apple guidelines is consistency • Effective applications are both consistent within themselves and consistent with one another. • More concrete guideline • ‘noun-verb’ ordering – user selects an object on desktop, then the operation

  11. Dialog Initiative • Under general usability category of flexibility principle • The user, not the computer, initiates and controls all actions • Involves a trade-off • user freedom vs system protection

  12. GUI Systems • Guidelines on how to adhere to abstract principles for usability in programming environment • Style guides • OpenLook • Open Software Foundation Motif GUI • involve using toolkits with high-level widgets • each have own look-and-feel • promote consistency

  13. OpenLook example • For design of menus • Suggestion for grouping items in the same menu • “Use white space between long groups of controls on menus or in short groups when screen real estate is not an issue.” • Justification: more options on a menu, longer it takes user to locate and point to item • Careful: grouping logically related items like saving and deleting files may result in a simple slip in pointing

  14. Golden Rules (Heuristics) • Broad-brush design rules, may not be applicable in every case • Shneiderman’s 8 Golden rules of interface design • convenient and succinct • used in design, but can be used for evaluation • relate to abstract principles

  15. Shneiderman’s 8 Golden rules of interface design • Strive for consistency • Enable frequent users to use shortcuts • Offer informative feedback • Design dialogs to yield closure • Offer error prevention and simple error handling • Permit easy reversal of actions • Support internal locus of control so user is in control • Reduce short-term memory load

  16. Norman’s 7 Principles for Transforming Difficult Tasks into Simple Ones • Use both knowledge in world and in the head • Simplify the structure of tasks • Make things visible – bridge gulfs of execution and evaluation • Get mappings right • Exploit the power of constraints • Design for error. • When all fails, standardize. (when no natural mappings)

  17. HCI Patterns • Approach to capture and reuse knowledge • Patterns abstract essential details of successful design, so they can be applied again in new situations. • Originated in architecture • Used in software development to capture solutions to common programming problems • More recently in interface and web design

  18. HCI Patterns • A Pattern • ‘go back to safe place’ example in Figure 7.3 • Pattern states • the problem • the solution • the rationale • where pattern came from • what context it applies in • example illustrating the pattern • references to other patterns (which may be needed to complete it) • A Wizard Pattern