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Brugergrænseflader til apparater BRGA Presentation 4: Guidelines & Heuristics.

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Presentation on theme: "Brugergrænseflader til apparater BRGA Presentation 4: Guidelines & Heuristics."— Presentation transcript:

1 Brugergrænseflader til apparater BRGA Presentation 4: Guidelines & Heuristics

2 2 Outline Recap Until Now Cognitive HCI & Methods that we employ Cognitive Walkthrough Methods vs. Guidelines & Heuristics Types of Guidelines & Heuristics Nielsen’s 9 (10) Heuristics and How to use Other Guidelines Patterns of Usability Method: Heuristic Evaluation

3 3 Until Now Cognitive HCI & Human Capabilities The Human Mind as an information processor The Human Body as input/output Hard Science Predictions/Calculations GOMS/KLA/Fitts Law Methods for analysis Expert review Designers: CW Today Distilled experiences: Guidelines & Heuristics + Heuristic Evaluation

4 Today: Usability Heuristics Avoid common design pitfalls by following design principles: guidelines & heuristics Inspect an interface for usability problems with these principles (Heuristic evaluation)

5 Design principles Broad usability statements that guide a developer’s design efforts use the users language provide feedback… Derived from common design problems across many systems and many researchers and developers experiences = Patterns of Usability

6 6 Available guidelines General guidelines Shneiderman’s 8 Golden Rules of Interface Design Nielsen’s 9 principles of design Normans 4 principles of good design Molich’s 5 guidelines for screen dialogs MANY OTHERS – look for yourselves at ACM and Cite Seer Area specific guidelines Agricultural Mobile / Office Workers Leisure activities (designing for the home) Technology/Platform specific guidelines Windows (Microsoft guidelines), MS SmartPhone, Tablet PC, Apple, Nokia WAP Guidelines, ELO Touchscreen

7 7 Usability Patterns Usability Patterns are emerging Relates to many of the same issues Has design scope – not review We will look at some later

8 8 General Guidelines & Heuristics Guidelines = Heuristics = Experiences We will be looking at Nielsen’s 9 guidelines next Guidelines are easy to understand, so I will not spend time introducing you to them in detail – please read Remember: be critical

9 9 Usability Engineering – Jakob Nielsen Nine principles of design 1.Simple and natural dialog 2.Speak the user’s language 3.Minimize user’s memory load 4.Be consistent 5.Provide feedback 6.Provide clearly marked exits 7.Provide shortcuts 8.Deal with errors in a positive manner 9.Provide help (+ Prevent Errors in BRGA-1) Heuristic Evaluation Fairly coarse grained model

10 1. Simple and natural dialogue use the user’s conceptual model match the users’ task sequence minimize mapping between interface and task semantics From Microsoft applications Only display what is Useful for the current task

11 11 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 remove modes Redesigned from 5 clicks to 1 + more natural mapping. All daily tasks were mapped to main screen

12 12 1. Simple and natural dialogue Microsoft Inductive User Interface Guidelines Deductive Deduce: to conclude by reasoning The user must deduce from interface “What do I have to do here?” Bad user mental model support Inductive Induce: to lead or move by influence or persuasion Split dialogs into simple task atomic units that only have one purpose Less is more principle

13 13 My program gave me the message Rstrd Info. What does it mean? That’s restricted information But surely you can tell me!!! No, no… Rsdrd Info stands for “Restricted Information” Hmm… but what does it mean??? It means the program is too busy to let you log on Ok, I’ll take a coffee 2. Speak the users’ language

14 Terminology based on users’ language for task e.g. withdrawing money from a bank machine Use meaningful mnemonics, icons & abbreviations eg File / Save Ctrl + S (abbreviation) Alt FS (mnemonic for menu action) (tooltip icon)

15 15 2. Speak the users’ language Glossary: UK English -> US English -> DK English Use Mappings and Metaphors Between users conceptual model and the information appliances’ display > may be achieved by understanding the users work domain and jargon (e.g. through field studies & interviews) Draw on the users ”non-technical” knowledge by using metaphors e.g. ”trash can” for removing files Problem: metaphors may deceive the users (the trash can does NOT completely remove the file from disk) “Upcomming Bills” -> “Pick the Bill you would like to pay”

16 3. Minimize user’s memory load Computers good at remembering, people are not! Promote recognition over recall menus, icons, choice dialog boxes vs commands, field formats, support data entry best possible to reduce errors relies on visibility of objects to the user (but less is more!) From Microsoft applications

17 17 3. Minimize user’s memory load Cognitive Overload

18 4. Be consistent Consistency -> confident users -> explanatory learning Consistent syntax of input (within MS Windows, application, and the dialog) Consistent language and graphics same visual appearance across the system (e.g. widgets) same information/controls in same location on all windows Microsoft IUI: Use Templates Consistent effects commands, actions have same effect in equivalent situations predictability, reliability OkCancelOkCancelAcceptDismiss Cancel Ok

19 19 4. Be Consistent Beware of conventions learned with other products might become a problem: Where to expect the power button?

20 5. Provide feedback Continuously inform the user about what the system is doing how it is interpreting the user’s input user should always be aware of what is going on > Doit What’s it doing? > Doit This will take 5 minutes... Time for coffee. Support the users mental model of the system state

21 21 5. Provide feedback What did I select? What mode am I in now? How is the system interpreting my actions? Microsoft Paint

22 22 5. Provide feedback Provide constant feedback Also provide partial information While throwing coins into the vending machine, update for each coin When a problem occurs – light the display, and turn it off again as soon as the problem is resolved Support Mental Model of Users at all times

23 23 5. Provide feedback Be as specific as possible, based on user’s input Best within the context of the action – context supports good mapping of system image and mental model

24 24 5. Provide feedback Response time - how users perceive delays: < 0.1 s perceived as “instantaneous” 1 s user’s flow of thought stays uninterrupted, but delay noticed 10 s limit for keeping user’s attention focused on the dialog > 10 s user will want to perform other tasks while waiting

25 Dealing with long delays – use “action symbols” Cursors for short transactions typically < 10s Percent done dialogs time left estimated time In case of no clue? tell the user 5. Provide feedback

26 How do I get out of this? 6. Provide clearly marked exits

27 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) BE CONSISTENT Dangerous with limited undo Core Dump

28 7. Provide shortcuts Experienced users - perform frequent operations quickly Strategies: keyboard and mouse accelerators abbreviations command completion context menus function keys double clicking vs menu selection navigation jumps e.g., going to window/location directly, and avoiding intermediate nodes history systems www: ~60% of pages are revisits

29 29 Keyboard accelerators for menus Customizable toolbars and palettes for frequent actions Split menu, with recently used fonts on top Scrolling controls for page-sized increments Double-click raises object- specific menu Double-click raises toolbar dialog box Support multiple accelerator technologies

30 8. Deal with errors in a positive manner Errare humanum est - People will make errors! Errors we make: Mistakes conscious deliberations lead to an error instead of correct solution – often because of bad UI mappings Slips unconscious behaviour gets misdirected en route to satisfying goal –e.g. drive to store, end up in the office, juice in bowl –usually due to inattention, interruptions –often arises from similar actions (deleting inbox instead of draft)

31 Designing for slips General rules prevent slips before they occur detect and correct slips when they do occur user correction through feedback and undo support the mental model of the user context should be kept clear avoid modes I can’t believe I pressed Yes...

32 A problematic message to a nuclear power plant operator 8. Deal with errors in a positive manner

33 33 Adobe's ImageReady AutoCAD Mechanical Windows Notepad Microsoft's NT Operating System 8. Deal with errors in a positive manner

34 Provide meaningful error messages error messages should be in the user’s task language don’t make people feel stupid – help them 1.“Error 25” 2.“Cannot open this document” 3.“Cannot open “chapter 5” because the application “Microsoft Word” is not on your system” 4.“Cannot open “chapter 5” because the application “Microsoft Word” is not on your system. Open it with “WordPad” instead?” 8. Deal with errors in a positive manner

35 Prevent errors try to make errors impossible modern widgets: can only enter legal data 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? User Interface Patterns Forgiving Format Input Hint

36 9. Provide help Help is not a replacement for bad design! Simple systems: walk up and use; minimal instructions Most other systems feature rich simple things should be simple learning path for advanced features Volume 37: A user's guide to...

37 Documentation and how it is used Many users do not read manuals prefer to spend their time pursuing their task Usually used when users are in some kind of panic paper manuals unavailable in many businesses online documentation better good search/lookup tools online help specific to current context Sometimes used for quick reference syntax of actions, possibilities... list of shortcuts... Volume 37: A user's guide to...

38 38 Excercise (5 min.) Each student gets 1 heuristic Find good examples (2 min.) Plenum

39 39 Top 10 Usability Guidelines for WAP 1.Implement navigational menus using a elements 2.Keep soft key labels to 5 characters or less. 3.Use Wizards instead of forms 4.Keep the content that appears above select and input fields to 1 or 2 lines max (including images). 5.Assign the most commonly chosen action or most intuitive task to the accept soft key 6.Don't use the task to navigate to a card that is already on the history stack 7.Allow the user to dial phone calls from the application by pressing a single key 8.Use the format attribute to constrain text input fields to only allow valid character types 9.Don't set a deck's expiration (maxage) to a low value unless the content is highly volatile 10.Ensure all decks are smaller than 500 bytes

40 40 Design Guidelines for Windows Excerpts from Microsoft on “Visual Design”: Color: Some percentage of the population may have color- identification problems. This can affect the accessibility of your software to the widest possible audience. For example, about 9 percent of the adult male population have some form of color confusion. Access Keys: Always define an access key for the label of any control or menu item. The only exceptions are the OK and Cancel buttons because the ENTER and ESC keys typically serve as the access keys to these buttons. Also, avoid having the same access key used by more than one control in a single context or more than one item on the same menu. Animation: Avoid gratuitous use of animation. When animation is used only for a decorative effect, it can distract or annoy the user. To use animation most effectively, use it for a specific purpose or condition. Avoid repeating the animation unless the condition persists or reoccurs. You should provide the user with the option of turning off the animation or otherwise customizing the animation effects.

41 41 Pocket PC Guidelines Pocket PC User Interface Guidelines Excerpts Usability: Use the following checklist to confirm that an application user interface meets basic usability requirements: Dialog boxes do not contain irrelevant information because it diminishes the visibility of relevant information. Information appears in a logical order in the dialog box based on the functionality provided. The information is communicated using words and concepts that are familiar to a user. Instructions for using an application are visible or easily accessible whenever appropriate. Avoid complicated instructions. When appropriate, the same user action is consistently used to complete the same application operation. Appropriate feedback is provided to a user within a reasonable time. Shortcuts for experienced users are provided for completing tasks. Tabs On Windows Mobile-based Pocket PCs, use tabs in an application to group related information and functionality. Consider the following when you include tabs in an application: So that the user does not need to scroll to view the tabs, avoid creating more tabs than can fit on the screen at one time. So that the user does not need to scroll to view the controls, ensure that all of the edit controls are visible on a property sheet when the input panel is displayed. To keep the content area uncluttered at the top of the screen, place tabs at the bottom of the screen. Label Attributes Use the 8pt, Tahoma black font

42 42 Touchscreen Guidelines Excerpts from Use a Simple Point-and-Click Interface Large buttons rule of Thumb-sized buttons No double-clicking No pull-down menus No scrolling or scroll bars No dragging Turn the Cursor Off Many more …

43 43 Touchscreen Guidelines Excerpts from SAPDesignGuilds guidelines Gestures Simple gestures, that are easy to remember, can be used on stylus-operated touchscreens for often-used functions. Gestures are simple "drawings" like letters or symbols. Here are a few examples: Deleting items by striking them through or crossing them out (the Apple Newton used a "W" for this operation. Marking items by adding a cross ("X") or "Ã". Identifying a user by his or her signature (handwriting). Gestures are not well suited to finger-operated touchscreens, as the use drag operations with fingers are not recommended in the literature. PDF:

44 Heuristic Evaluation Systematic inspection to see if interface complies to guidelines (could be these 9 – and/or others) Method 3-5 inspectors usability engineers, end-users, double experts… inspect interface in isolation ~1–2 hours for simple interfaces compare notes afterwards single evaluator only catches ~35% of usability problems 5 evaluators catch 75% (nielsen) Works for paper, hi-fi prototypes, and working systems

45 45 Heuristic Evaluation Method Breifing session Which interfaces & tasks to evaluate Usage scenario Which Heuristics to use Evaluation period Each evaluator is on his own for 1-2 hours Two passes of checks using the heuristics Record all problems Debriefing session Evaluators come together to discuss findings, prioritize the problems and suggest solutions

46 Heuristic Evaluation Advantages: “minimalist” approach a few guidelines identify many common usability problems easily remembered, easily applied with modest effort discount usability engineering / Gurillia HCI end users not required cheap and fast way to inspect a system – or even mock-up can be done by usability experts, double experts, and end users Problems: can’t be treated as a simple checklist subtleties involved in their use evaluators might not understand the domain for every 1 problem found, 1 false alarm and ½ is missed (preece et al.)


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