User Interface Design Guidelines & Development Strategies

1. SIMS 213: User Interface Design & Development Marti Hearst Tues, Feb 21, 2006

2. Today • Modes • Selected Design Guidelines • Heuristic Evaluation • How to do it • How well does it work? • In-class H.E.

3. Modes • What are they? • The same user actions have different effects in different situations. • Examples? • Keycaps lock • Adobe reader example: vs. • Powerpoint drawing example

6. Modes • When are they useful? • Temporarily restrict users’ actions • When logical and clearly visible and easily switchable • Drawing with paintbrush vs. pencil • Autocorrect (if easy to switch the mode) • Why can they be problematic? • Big memory burden • Source of many serious errors • How can these problems be fixed? • Don’t use modes – redesign the system to be modeless • Redundantly visible • Raskin -- quasimodes

7. Modal Blooper

8. Modal Blooper(and other problems too)

9. A Summary Statement • Raskin, p. 69 • “We must make sure that every detail of an interface matches both our cognitive capabilities and the demands of the task…”

10. Design Guidelines • There are LOTS of them • Based on common sense and experience • Not necessarily proven • Often conflict with one another • Often don’t say HOW to implement them

11. Design Guidelines • What do to: • Focus on those guidelines most applicable to the kind of interface under development • Focus on those emphasized in our readings • Bloopers, chapter 1 • Usability Engineering, chapter 5 • Raskin, chapter 3 • All of Don Norman’s concerns • Use common sense

12. All-Star Usability Design Guidelines An edited selection

13. 1 Simple and natural dialogue • Use the user’s conceptual model • Match the users’ task in as natural a way as possible • minimize mapping between interface and task semantics Slide adapted from Saul Greenberg

14. 1 Simple and natural dialogue • Present exactly the information the user needs • less is more • less to learn, to get wrong, to distract... • information should appear in natural order • related information is graphically clustered • order of accessing information matches user’s expectations • remove or hide irrelevant or rarely needed information • competes with important information on screen • use windows frugally • don’t make navigation and window management excessively complex

15. Slide adapted from Saul Greenberg

16. 2 Speak the users’ language • Examples? Slide adapted from Saul Greenberg

17. 3 Minimize user’s memory load • Computers good at remembering things, people aren’t! • Promote recognition over recall • menus, icons, choice dialog boxes vs command lines, field formats • relies on visibility of objects to the user (but less is more!) Slide adapted from Saul Greenberg

18. 3 Minimize user’s memory load Slide adapted from Saul Greenberg

19. 3: Minimize user’s memory load • Describe required input format and example, and default • Small number of rules applied universally • generic commands • same command can be applied to all interface objects • copy, cut, paste, drag ’n drop, ... for characters, words, paragraphs, circles, files Slide adapted from Saul Greenberg

20. 3: Minimize user’s memory load Slide adapted from Saul Greenberg

21. 4: Be consistent • Consistency of effects • same words, commands, actions will always have the same effect in equivalent situations • Consistency of language and graphics • same information/controls in same location on all screens / dialog boxes • same visual appearance across the system (e.g. widgets) • e.g. different scroll bars in a single window system! • Consistency of input • consistent syntax across complete system Slide adapted from Saul Greenberg

22. 4. Be Consistent These are labels with a raised appearance. Is it any surprise that people try and click on them? Slide adapted from Saul Greenberg

23. > Doit > Doit This will take5 minutes... 5: Provide feedback • Continuously inform the user about • what it is doing • how it is interpreting the user’s input • user should always be aware of what is going on Time for coffee. What’s it doing? Slide adapted from Saul Greenberg

24. 5. Provide feedback • Should be as specific as possible, based on user’s input • Best within the context of the action Slide adapted from Saul Greenberg

25. 5. Provide feedback What mode am I in now? What did I select? How is the system interpreting my actions? Slide adapted from Saul Greenberg

26. Provide feedback Multiple files being copied, but feedback is file by file. Drawing Board LT Slide adapted from Saul Greenberg

27. 5. Provide feedback • Response time • how users perceive delays 0.1 second max: perceived as “instantaneous” 1 second max: user’s flow of thought stays uninterrupted, but delay noticed 10 seconds: limit for keeping user’s attention focused on the dialog > 10 seconds: user will want to perform other tasks while waiting Slide adapted from Saul Greenberg

28. 6. Provide clearly marked exits How do I get out of this? Slide adapted from Saul Greenberg

29. 6. Provide clearly marked exits • Users don’t like to feel trapped by the computer! • should offer an easy way out of as many situations as possible • Strategies: • Cancel button (for dialogs waiting for user input) • Universal Undo (can get back to previous state) • Interrupt (especially for lengthy operations) • Quit (for leaving the program at any time) • Defaults (for restoring a property sheet) Slide adapted from Saul Greenberg

30. 7. Provide shortcuts • Experienced users should be able to perform frequently used operations quickly • Strategies: • keyboard and mouse accelerators • abbreviations • command completion • menu shortcuts • function keys • double clicking vs menu selection • type-ahead (entering input before the system is ready for it) navigation jumps • e.g., going to location directly, and avoiding intermediate nodes • history systems • WWW: ~60% of pages are revisits Slide adapted from Saul Greenberg

31. Keyboard accelerators for menus Customizable toolbars andpalettes for frequent actions Split menu, with recently used fonts on top Double-click raises toolbar dialog box Double-click raises object-specific menu Scrolling controls for page-sized increments

32. 8:Deal with errors in a positive and helpful manner • People will make errors! • Errors we make • Mistakes • arise from conscious deliberations that lead to an error instead of the correct solution • Slips • unconscious behaviour that gets misdirected en route to satisfying goal • e.g. drive to store, end up in the office • shows up frequently in skilled behaviour • usually due to inattention • often arises from similarities of actions Slide adapted from Saul Greenberg

33. Designing for slips • General rules • Prevent errors before they occur • Detect and correct errors when they do occur • User correction through feedback and undo Slide adapted from Saul Greenberg

34. Designing for slips • Examples • mode errors • have as few modes as possible (preferably none) • make modes highly visible • capture errors • instead of confirmation, make actions undoable • allows reconsideration of action by user • loss of activation • if system knows goal, make it explicit • if not, allow person to see path taken • description errors • in icon-based interfaces, make sure icons are not too similar, • check for reasonable input, etc. Slide adapted from Saul Greenberg

35. 8 Deal with errors in a positive and helpful manner • Prevent errors • try to make errors impossible • modern widgets: only “legal commands” selected, or “legal data” entered • Provide reasonableness checks on input data • on entering order for office supplies • 5000 pencils is an unusually large order. Do you really want to order that many? Slide adapted from Saul Greenberg

36. Volume 37: A user's guide to... 9. Provide help • Help is not a replacement for bad design! • Simple systems: • walk up and use; minimal instructions • Most other systems: • feature rich • some users will want to become “experts” rather than “casual” users • intermediate users need reminding, plus a learning path Slide adapted from Saul Greenberg

37. Types of help • Tutorial and/or getting started manuals • short guides that people are likely to read when first obtaining their systems • encourages exploration and getting to know the system • tries to get conceptual material across and essential syntax • on-line “tours”, exercises, and demos • demonstrates very basic principles through working examples Slide adapted from Saul Greenberg

38. Types of help • Reminders • short reference cards • expert user who just wants to check facts • novice who wants to get overview of system’s capabilities • keyboard templates • shortcuts/syntactic meanings of keys; recognition vs. recall; capabilities • tooltips • text over graphical items indicates their meaning or purpose Slide adapted from Saul Greenberg

39. Types of help • Context-sensitive help • system provides help on the interface component the user is currently working with • Tool tips • Macintosh “balloon help” • Microsoft “What’s this” help • brief help explaining whatever the user is pointing at on the screen Slide adapted from Saul Greenberg

40. Types of help • Wizards • walks user through typical tasks • but problematic if user gets stuck Slide adapted from Saul Greenberg

41. Types of help • Tips • migration path to learning system features • also context-specific tips on being more efficient • must be “smart”, otherwise boring and tedious Slide adapted from Saul Greenberg

42. Discount Usability Testing Heuristic Evaluation

43. Evaluating UI Designs • Usability testing is a major technique • “Discount” methods don’t require users • Heuristic Evaluation • Cognitive Walkthrough

44. Heuristic Evaluation • Developed by Jakob Nielsen • Helps find usability problems in a UI design • Small set (3-5) of evaluators examine UI • independently check for compliance with usability principles (“heuristics”) • different evaluators will find different problems • evaluators only communicate afterwards • findings are then aggregated • Can perform on working UI or on sketches

45. Phases of Heuristic Evaluation 1) Pre-evaluation training • give evaluators needed domain knowledge and information on the scenarios 2) Evaluation • individuals evaluate and then aggregate results 3) Severity rating • determine how severe each problem is (priority) 4) Debriefing • discuss the outcome with design team Adapted from slide by James Landay

46. H1-1: Simple & natural dialog H1-2: Speak the users’ language H1-3: Minimize users’ memory load H1-4: Consistency H1-5: Feedback H1-6: Clearly marked exits H1-7: Shortcuts H1-8: Precise & constructive error messages H1-9: Prevent errors H1-10: Help and documentation Heuristics (original)

47. How to Perform H.E. • At least two passes for each evaluator • first to get feel for flow and scope of system • second to focus on specific elements • Assistance from implementors/domain experts • If system is walk-up-and-use or evaluators are domain experts, then no assistance needed • Otherwise might supply evaluators with scenarios and have implementors standing by Adapted from slide by James Landay

48. How to Perform Evaluation • Where problems may be found • single location in UI • two or more locations that need to be compared • problem with overall structure of UI • something that is missing Adapted from slide by James Landay

49. Example Problem Descriptions • Can’t copy info from one window to another • Violates “Minimize the users’ memory load” (H1-3) • Fix: allow copying • Typography uses mix of upper/lower case formats and fonts • Violates “Consistency and standards” (H2-4) • Slows users down • Probably wouldn’t be found by user testing • Fix: pick a single format for entire interface Adapted from slide by James Landay

50. Severity Ratings • Used to allocate resources to fix problems • Estimates of need for more usability efforts • Combination of • frequency • impact • persistence (one time or repeating) • Should be calculated after all evaluations are done • Should be done independently by allevaluators Adapted from slide by James Landay