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CS305, HCI in Software Development Usability Goals, Principles, Guidelines

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Title: CS305, HCI in Software Development Usability Goals, Principles, Guidelines


1
CS305, HCI in Software DevelopmentUsability
Goals, Principles, Guidelines
  • (Introduction, Part 2)
  • Fall 2008

2
Activity (Mini-Homework)
  • Do this on your own on in pairs
  • Go find two examples of problems in the GUIs of
    software apps or the UI of a interactive device
    (not Web pages)
  • Problem must illustrate a violation of one of the
    design principles or usability guidelines
  • Describe the problems in these terms
  • Post on Collab wiki page before class next Fri.

3
Reminder.
  • users should be involved through the development
    of the project
  • specific usability and user experience goals
    need to be identified, clearly documented and
    agreed at the beginning of the project
  • iteration is needed through the core activities

4
Towards More Usable Systems
  • Seems like we need the following
  • Goals we want to achieve
  • Principles on how to achieve these
  • Lists of dos and donts
  • Theories that underlie principles, lists
  • Methods for measuring and evaluating

5
Usability Goals
  • Heres one set (from the ID textbook)
  • Effective to use
  • Efficient to use
  • Safe to use
  • Have good utility
  • Easy to learn
  • Easy to remember how to use

6
Usability Goals
  • Effective to use (effectiveness)
  • A general goal how well does a system do what it
    should do?
  • Efficient to use (efficiency)
  • Do things quickly, easily.
  • Especially common tasks.
  • Safe to use (safety)
  • Protect people from hazards (usually not a SW
    issue)
  • Help prevent user from making errors and recover
    from errors
  • Give users confidence

7
Usability Goals (2)
  • Have good utility
  • Has the right kind of functionality
  • Supports users in accomplishing tasks
  • Easy to learn (learnability)
  • Includes how easy it is to learn advanced
    features. (If hard, who bothers?)
  • Easy to remember how to use (memorability)
  • Many systems used infrequently

8
How to Measure Usability?
  • We want to achieve these goals, but how do we
    know?
  • Develop measurable criteria based on previous
    goals. Examples
  • Time to learn
  • Speed of performance
  • Rate of errors over by users
  • Retention over time
  • Subjective satisfaction

9
User experience goals
  • Satisfying - rewarding
  • Fun - support creativity
  • Enjoyable - emotionally fulfilling
  • Entertaining and more
  • Helpful
  • Motivating
  • Aesthetically pleasing

10
Usability and user experience goals
  • How do usability goals differ from user
    experience goals?
  • How easy is it to measure usability versus user
    experience goals?
  • Are there trade-offs between the two kinds of
    goals?
  • e.g. can a product be both fun and safe?

11
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12
Reminder of where we are
  • Usability Goals
  • Some measures
  • User Experience Goals
  • Design Principles
  • First two were higher level (goals)
  • Now talking about guidance for how to achieve
    goals
  • Guidelines (guidance as lists)

13
Design principles
  • Generalizable abstractions for thinking about
    different aspects of design
  • The dos and donts of interaction design
  • But at a high level. (Compare to guidelines
    later.)
  • What to provide and what not to provide at the
    interface
  • Derived from a mix of theory-based knowledge,
    experience and common-sense

14
Higher-level Principles
  • Now, well talk about the following
  • Visibility
  • Feedback
  • Constraints
  • Mapping
  • Consistency
  • Affordances
  • Ideas well-known (e.g. from Normans Design of
    Everyday Things)

15
Activity (Mini-Homework)
  • Do this on your own on in pairs
  • Go find two examples of problems in the GUIs of
    software apps or the UI of a interactive device
    (not Web pages)
  • Problem must illustrate a violation of one of the
    design principles or usability guidelines
  • Describe the problems in these terms
  • Post on Collab wiki page before class next Fri.

16
Visibility
  • This is a control panel for an elevator.
  • How does it work?
  • Push a button for the floor you want?
  • Nothing happens. Push any other button? Still
    nothing. What do you need to do?
  • It is not visible as to what to do!

From www.baddesigns.com
17
Visibility
you need to insert your room card in the slot by
the buttons to get the elevator to work!
  • How would you make this action more visible?
  • make the card reader more obvious
  • provide an auditory message, that says what to do
    (which language?)
  • provide a big label next to the card reader that
    flashes when someone enters
  • make relevant parts visible
  • make what has to be done obvious

18
Feedback
  • Sending information back to the user about what
    has been done
  • Includes sound, highlighting, animation and
    combinations of these
  • e.g. when screen button clicked on provides sound
    or red highlight feedback

ccclichhk
19
Constraints
  • Restricting the possible actions that can be
    performed
  • Helps prevent user from selecting incorrect
    options
  • Three main types (Norman, 1999)
  • physical
  • cultural
  • logical

20
Physical constraints
  • Refer to the way physical objects restrict the
    movement of things
  • E.g. only one way you can insert a key into a
    lock
  • How many ways can you insert a CD or DVD disk
    into a computer?
  • How physically constraining is this action?
  • How does it differ from the insertion of a floppy
    disk into a computer?

21
Logical constraints
  • Exploits peoples everyday common sense reasoning
    about the way the world works
  • An example is the logical relationship between
    physical layout of a device and the way it works
  • See next slide for an illustration

22
Logical or ambiguous design?
  • Where do you plug the mouse?
  • Where do you plug the keyboard?
  • top or bottom connector?
  • Do the color coded icons help?

From www.baddesigns.com
23
More Logically Constrained
  • Provides direct adjacent mapping between icon and
    connector
  • Provides color coding to associate the connectors
    with the labels

From www.baddesigns.com
24
Cultural constraints
  • Learned arbitrary conventions like red
    triangles for warning
  • Can be universal or culturally specific
  • For SW weve accepted certain conventions, e.g.
    we know what to do with an icon
  • Be concerned of cross-cultural conventions and
    other ambiguities!
  • Does an X mean selected or not selected
  • Is a check-mark better?

25
Which are universal and which are
culturally-specific?
26
Mapping
  • Relationship between controls and their movements
    and the results in the world
  • Why is this a poor mapping of control buttons?

27
Mapping
  • Why is this a better mapping?
  • The control buttons are mapped better onto the
    sequence of actions of fast rewind, rewind, play
    and fast forward
  • Is this a logical mapping (in most peoples
    minds)?
  • Is there a mapping that makes more sense?

28
Mappings in the Kitchen
  • Which controls go with which rings (burners)?

A
B
C
D
29
Why is this a better design?
30
Consistency
  • Design interfaces to have similar operations and
    use similar elements for similar tasks
  • For example
  • always use ctrl key plus first initial of the
    command for an operation ctrlC, ctrlS, ctrlO
  • Main benefit is consistent interfaces are easier
    to learn and use
  • But didnt a wise man say this? Consistency
    is the hobgoblin of little minds.
  • A foolish consistency is the hobgoblin of little
    minds(adored by little statesmen and
    philosophers and divines)

31
When consistency breaks down
  • What happens if there is more than one command
    starting with the same letter?
  • e.g. save, spelling, select, style
  • Have to find other initials or combinations of
    keys, thereby breaking the consistency rule
  • E.g. ctrlS, ctrlSp, ctrlshiftL
  • Is this desirable? Does it defeat the purpose?
  • It may increase learning burden on user
  • It may make them more prone to errors
  • But it may still benefit frequent or experienced
    users

32
Internal and external consistency
  • Internal consistency refers to designing
    operations to behave the same within an
    application
  • Difficult to achieve with complex interfaces
  • External consistency refers to designing
    operations, interfaces, etc., to be the same
    across applications and devices
  • Very rarely the case, based on different
    designers preference
  • Most successful in product families (e.g MS
    Office)
  • Op. Sys. vendors may define style guidelines

33
Keypad numbers layout
  • A case of external inconsistency

(a) phones, remote controls
(b) calculators, computer keypads
8
9
1
2
7
3
4
5
6
4
5
6
8
9
1
2
7
3
0
0
34
Affordances to give a clue
  • Refers to an attribute of an object that allows
    people to know how to use it
  • E.g. a mouse button invites pushing, a door
    handle affords pulling
  • Norman (1988) used the term to discuss the design
    of everyday objects
  • Since then has been popularized in interaction
    design to discuss how to design interface objects
  • E.g. scrollbars to afford moving up and down,
    icons to afford clicking on

35
What does affordance have to offer interaction
design?
  • Notion of affordance is often over-used!http//ww
    w.jnd.org/dn.mss/affordances-and.html
  • Interfaces are virtual and do not have
    affordances like physical objects
  • Norman argues it does not make sense to talk
    about interfaces in terms of real affordances
  • Instead interfaces are better conceptualised as
    perceived affordances
  • Learned conventions of arbitrary mappings between
    action and effect at the interface
  • Some mappings are better than others

36
Activity 1.3
  • Physical affordances
  • How do the following physical objects afford? Are
    they obvious?

37
Activity 1.4
  • Virtual affordances
  • How do the following screen objects afford?
  • What if you were a novice user?
  • Would you know what to do with them?

38
Activity 1.5 Physical and Perceived Affordances
  • Take a cell phone, digital camera, or PDA
  • Have laptop? Open a fancy SW app Outlook,
    Eclipse, etc?
  • In a small group
  • Identify any physical affordances the device has
  • Identify any perceived or visual affordances the
    software user interface has
  • Write these down, be prepared to share or turn in

39
A Good Example
  • Kodak DC-290 digital camera

40
Adjusting Tabs in MS Word
  • Whats the idea here? Problems?
  • What principle(s)?
  • Affordance
  • Metaphor (more on this later)

41
Web Links
  • What are the conventions that help you recognize
    a link?
  • Would you are argue this is an affordance?
  • A perceived affordance convention of a mapping
    between action and effect
  • Does it afford clicking on it?
  • Examples of problems with this?
  • Lets look at http//www.cs.virginia.edu

42
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43
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44
Overview (Reminder)
  • Usability Goals
  • User Experience Goals
  • Design Principles
  • Guidelines
  • Still talking about guidance for how to achieve
    goals
  • These are more prescriptive (dos donts)

45
Guidelines
  • What do we mean by guidelines?
  • Tell me!
  • Are guidelines enough? Lead to problems?
  • Too specific, incomplete. Dont generalize to
    all situations
  • But Capture experience and best practices
  • Many examples of guidelines

46
Nature of Guidelines
  • Similar to design principles, except more
    prescriptive
  • Used mainly as the basis for evaluating systems
  • Provide a framework for heuristic evaluation
  • Well talk about particular approach to
    evaluation this later

47
Jakob Nielsen Says
  • Jakob Nielsen a leading figure in usability
  • Member of the Nielsen Norman Group
  • Donald Norman
  • Bruce "Tog" Tognazzini
  • http//www.useit.com/
  • Alertbox regular column
  • Wikipedia http//en.wikipedia.org/wiki/Jakob_Niel
    sen_(usability_consultant)

48
Usability principles (Nielsen 2001)
  • Visibility of system status
  • Match between system and the real world
  • User control and freedom
  • Consistency and standards
  • Help users recognize, diagnose and recover from
    errors
  • Error prevention
  • Recognition rather than recall
  • Flexibility and efficiency of use
  • Aesthetic and minimalist design
  • Help and documentation

49
Read More about Nielsens List(s)
  • Nielsens site has more on the previous
    listhttp//www.useit.com/papers/heuristic/heurist
    ic_list.html
  • Heuristics more general guidelines
  • Well see this term again
  • Heuristic evaluation
  • Activity 1.7 for you to do
  • Find one list of similar usability principles
    (i.e heuristics, prescriptive guidelines,
    dos/donts) for Web page design
  • Write it down well collect these

50
Shneidermans Eight Golden Rules
  1. Strive for consistency
  2. Cater to universal usability
  3. Offer informative feedback
  4. Design dialogs to yield closure
  5. Prevent errors
  6. Permit easy reversal of actions
  7. Support internal locus of control
  8. Reduce short-term memory load.

51
More Specific Guideline Examples from DTUI
  • Shneidermans text (DTUI) gives some more
    detailed examples
  • National Cancer Institute, p. 62
  • W3C, Accessibility, p. 62
  • Display organization, p. 63
  • Control rooms, p. 63
  • Others in Section 2.2
  • Ask yourself what principle(s) underlie each
    guideline?

52
Ex. 1 National Cancer Institute
  • 388 guidelines for informative web pages, such
    as
  • Reduce users workload
  • Do not display unsolicited windows or graphics
  • Standardize task sequences
  • Ensure embedded links are descriptive
  • Use unique and descriptive headings
  • Develop pages that print properly
  • Use thumbnail images to preview large images

53
Ex. 2a, Organizing Data Display
  • From Smith and Mozier (1986).
  • Data display 5 high-level goals
  • Consistency of data display
  • Efficient information assimilation by the user
  • Minimal memory load on the user
  • Compatibility of data display with data entry
  • Flexibility for user control of data display
  • Data entry 5 similar high-level goals, but also
  • Minimal input actions by user

54
Ex. 2b, More Specific than 2a
  • Lockheed (1981) on control rooms
  • Be consistent in labeling, graphics, formatting
  • Standardize abbreviations
  • Present data only if it assists the operator
  • Present data graphically where appropriate
    instead of numbers and text
  • Rely on monochromatic displays with good spacing
    and arrangement, saving color for when it helps
  • Involve users in development of displays

55
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56
Activity (Mini-Homework)
  • Do this on your own on in pairs
  • Go find two examples of problems in the GUIs of
    software apps or the UI of a interactive device
    (not Web pages)
  • Problem must illustrate a violation of one of the
    design principles or usability guidelines
  • Describe the problems in these terms
  • Post on Collab wiki page before class next Fri.
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