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Design, prototyping and construction The Task-Centered Design Process figure out who's going to use the system to do what choose representative tasks.

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Presentation on theme: "Design, prototyping and construction The Task-Centered Design Process figure out who's going to use the system to do what choose representative tasks."— Presentation transcript:


2 Design, prototyping and construction

3 The Task-Centered Design Process figure out who's going to use the system to do what choose representative tasks for task- centered design plagiarize rough out a design think about it create a mock-up or prototype test it with users iterate build it track it change it

4 Overview Prototyping and construction Conceptual design Physical design Tool support

5 Two guidelines for design 1. Provide a good conceptual model –allows user to predict the effects of our actions –problem: designers conceptual model communicated to user through system image: –appearance, written instructions, system behaviour through interaction, –transfer, idioms and stereotypes if system image does not make model clear and consistent, user will develop wrong conceptual model

6 Two guidelines for design (continued) 2. Make things visible –relations between users intentions, required actions, and results are sensible non arbitrary meaningful –visible affordances, mappings, and constraints –use visible cultural idioms –reminds person of what can be done and how to do it

7 Prototyping and construction What is a prototype? Why prototype? Different kinds of prototyping low fidelity high fidelity Compromises in prototyping vertical horizontal Construction

8 What is a prototype? In other design fields a prototype is a small-scale model: a miniature car a miniature building or town

9 What is a prototype? In interaction design it can be (among other things): a series of screen sketches a storyboard, i.e. a cartoon-like series of scenes a Powerpoint slide show a video simulating the use of a system a lump of wood (e.g. iphone) a cardboard mock-up a piece of software with limited functionality written in the target language or in another language

10 Why prototype? Evaluation and feedback are central to interaction design Stakeholders can see, hold, interact with a prototype more easily than a document or a drawing Team members can communicate effectively You can test out ideas for yourself It encourages reflection: very important aspect of design Prototypes answer questions, and support designers in choosing between alternatives

11 What to prototype? Technical issues Work flow, task design Screen layouts and information display Difficult, controversial, critical areas

12 Low-fidelity Prototyping Uses a medium which is unlike the final medium, e.g. paper, cardboard Is quick, cheap and easily changed Examples: sketches of screens, task sequences, etc Post-it notes storyboards Wizard-of-Oz



15 Storyboards Often used with scenarios, bringing more detail, and a chance to role play It is a series of sketches showing how a user might progress through a task using the device Used early in design

16 Sketching Sketching is important to low-fidelity prototyping Dont be inhibited about drawing ability. Practice simple symbols

17 Index cards (3 X 5 inches) Each card represents one screen Often used in website development Using index cards

18 Wizard-of-Oz prototyping The user thinks they are interacting with a computer, but a developer is responding to output rather than the system. Usually done early in design to understand users expectations What is wrong with this approach? >Blurb blurb >Do this >Why? User

19 High-fidelity prototyping Uses materials that you would expect to be in the final product. Prototype looks more like the final system than a low-fidelity version. For a high-fidelity software prototype common environments include Macromedia Director, Visual Basic, and Smalltalk. Danger that users think they have a full system…….see compromises

20 Compromises in prototyping All prototypes involve compromises For software-based prototyping maybe there is a slow response? sketchy icons? limited functionality? Two common types of compromise horizontal: provide a wide range of functions, but with little detail vertical: provide a lot of detail for only a few functions Compromises in prototypes mustnt be ignored. Product needs engineering

21 Construction Taking the prototypes (or learning from them) and creating a whole Quality must be attended to: usability (of course), reliability, robustness, maintainability, integrity, portability, efficiency, etc Product must be engineered Evolutionary prototyping Throw-away prototyping

22 Conceptual design: from requirements to design Transform user requirements/needs into a conceptual model a description of the proposed system in terms of a set of integrated ideas and concepts about what it should do, behave and look like, that will be understandable by the users in the manner intended Dont move to a solution too quickly. Iterate, iterate, iterate Consider alternatives: prototyping helps

23 Three perspectives for a conceptual model Which interaction mode? How the user invokes actions Activity-based: instructing, conversing, manipulating and navigating, exploring and browsing. Object-based: structured around real-world objects

24 Three perspectives for a conceptual model Which interaction paradigm? desktop paradigm, with WIMP interface (windows, icons, menus and pointers), ubiquitous computing pervasive computing wearable computing mobile devices and so on. Is there a suitable metaphor? (contd)….

25 Is there a suitable metaphor? Interface metaphors combine familiar knowledge with new knowledge in a way that will help the user understand the product. Three steps: understand functionality, identify potential problem areas, generate metaphors Evaluate metaphors: How much structure does it provide? How much is relevant to the problem? Is it easy to represent? Will the audience understand it? How extensible is it?

26 Interface metaphors Interface designed to be similar to a physical entity but also has own properties –e.g. desktop metaphor, web portals Can be based on activity, object or a combination of both Exploit users familiar knowledge, helping them to understand the unfamiliar Conjures up the essence of the unfamiliar activity, enabling users to leverage of this to understand more aspects of the unfamiliar functionality

27 Benefits of interface metaphors Makes learning new systems easier Helps users understand the underlying conceptual model Can be very innovative and enable the realm of computers and their applications to be made more accessible to a greater diversity of users

28 Problems with interface metaphors Break conventional and cultural rules –e.g. recycle bin placed on desktop Can constrain designers in the way they conceptualize a problem space Conflict with design principles Forces users to only understand the system in terms of the metaphor Designers can inadvertently use bad existing designs and transfer the bad parts over Limits designers imagination in coming up with new conceptual models







35 Expanding the conceptual model What functions will the product perform? What will the product do and what will the human do (task allocation)? How are the functions related to each other? sequential or parallel? categorisations, e.g. all actions related to telephone memory storage What information needs to be available? What data is required to perform the task? How is this data to be transformed by the system?

36 Physical design: getting concrete Considers more concrete, detailed issues of designing the interface Iteration between physical and conceptual design Guidelines for physical design Nielsens heuristics Coopers About Face 2.0 Styles guides: commercial, corporate decide look and feel for you widgets prescribed, e.g. icons, toolbar

37 Alan Coopers Excise Traps Dont force the user to go to another window to perform a function that affects this window Dont force the user to remember where he put things in the hierarchical file system Dont force the user to resize windows unnecessarily Dont force the user to move windows Dont force the user to reenter personal settings

38 Coopers Excise Traps Dont force the user the fill fields to satisfy some arbitrary measure of completeness Dont force the user to ask permission to make changes. Dont ask the user to confirm his actions. Dont let the users actions result in an error.

39 Direct manipulation Direct manipulation captures the idea of direct manipulation of the object of interest (Shneiderman 1983: p. 57), which means that objects of interest are represented as distinguishable objects in the UI and are manipulated in a direct fashion. Characteristics: Visibility of the object of interest. Rapid, reversible, incremental actions. Replacement of complex command language syntax by direct manipulation of the object of interest. Drag and drop files

40 One of the earliest commercially available direct manipulation interfaces was MacPaint

41 Direct Manipulation Advantages Visually presents task concepts. Easy to learn. Errors can be avoided more easily. Encourages exploration. High subjective satisfaction. Recognition memory (as opposed to cued or free recall memory) Disadvantages May be more difficult to program. Not suitable for small graphic displays. Spatial and visual representation is not always preferable. Metaphors can be misleading since the the essence of metaphor is understanding and experiencing one kind of thing in terms of another (Lakoff and Johnson 1983: p. 5), which, by definition, makes a metaphor different from what it represents or points to. Compact notations may better suit expert users.

42 Dont Mode me in UNIX vi is an example of evil modes –same actions have different meanings depending on context –edit replaces your file with t Paint programs are a good example of good modes. –Modes are visible

43 Rules for modes Use modes consistently Do not initiate modes unexpectedly Make modes visible Make it easy to escape modes … without consequences.

44 Physical design: getting concrete Different kinds of widget (dialog boxes, toolbars, icons, menus etc) menu design icon design screen design information display

45 Icon design Good icon design is difficult Meaning of icons is cultural and context sensitive Some tips: always draw on existing traditions or standards concrete objects or things are easier to represent than actions From clip art, what do these mean to you?

46 Screen design Two aspects: How to split across screens moving around within and between screens how much interaction per screen? Individual screen design white space: balance between enough information/interaction and clarity grouping items together: separation with boxes? lines? colors?

47 Screen design: individual screen design Draw user attention to salient point, e.g. colour, motion, boxing Animation is very powerful but can be distracting Good organization helps: grouping, physical proximity Trade off between sparse population and overcrowding

48 Principles of Visual interface design Avoid visual noise and clutter Use contrast, similarity, and layering to distinguish and organize elements Provide visual structure and flow at each level of organization Use cohesive, consistent, and contextually appropriate imagery Integrate style and function comprehensively and purposefully Alan Cooper, Robert M. Reimann. About Face 2.0: The Essentials of Interaction Design. Page 227.

49 Organization of Screen Elements Balance Symmetry Regularity Predictability Sequentiality Economy Unity Proportion Simplicity Groupings

50 Balance Equal weight of screen elements –Left to right, top to bottom

51 Balance Unstable

52 Balance Left column processed - Right column noted as same Both columns need to be understood by visual processing system

53 Symmetry Replicate elements left and right of the center line

54 Symmetric Asymmetric

55 Regularity Create standard and consistent spacing on horizontal and vertical alignment points

56 Regularity Left column processed - 2 right columns noted as same Location & size of each object processed

57 Predictability Put things in predictable locations on the screen

58 Predictable Spontaneous Icon FileEditViewInsertWindow Help Kung Foo Search for Movies CancelOK Enter Keywords : GrasshopperOld blind guy Icon FileEditViewInsertWindowHelp Kung Foo Search for MoviesCancel OK Enter Keywords : GrasshopperOld blind guy

59 Predictability User expects title & menu bar on top of screen Visual scene needs to be completely processed - objects not in expected places Icon File Edit View Insert Window Help Kung Foo Search for Movies CancelOK Enter Keywords : GrasshopperOld blind guy Icon File Edit View Insert Window Help Kung Foo Search for MoviesCancel OK Enter Keywords : GrasshopperOld blind guy

60 Sequentiality Guide the eye through the task in an obvious way –The Eye is attracted to: bright elements over less bright Isolated elements over grouped graphics before text color before monochrome saturated vs. less saturated colors dark areas before light big vs. small elements unusual shapes over usual ones

61 Screen design: splitting functions across screens Task analysis as a starting point Each screen contains a single simple step? Frustration if too many simple screens Keep information available: multiple screens open at once

62 Sequential Random Membership Form Name: Address: City: State: Zip: Dues: Pubs: Total: OKCancel Membership FormName: Address: City: State: Zip: Dues: Pubs: Total: OKCancel

63 Economy Use as few styles, fonts, colors, display techniques, dialog styles, etc., as possible

64 Economical Busy Membership Form Name: Address: City: State: Zip: Dues: Pubs: Total: OKCancel Membership Form Name: Address: City: State: Zip: Dues: Pubs: Total: OK Cancel

65 Unity Make items appear as a unified whole (for visual coherence) –Use similar shapes, sizes, or colors –Leave less space between screen elements than at the margin of the screen

66 Unity Fragmentation

67 Proportion Create groupings of data or text by using aesthetically pleasing proportions

68 Square - 1:1Square Root of 2 - 1:1.414Golden Triangle - 1:1.618 Square Root of 3 - 1:1.732Double Square - 1:2 Pleasing Proportions

69 Simplicity Minimize the number of aligned points –Use only a few columns to display screen elements Combine elements to minimize the number of screen objects –Within limits of clarity

70 Simplicity Only four alignments need to be processed A total of nine alignments need to be processed Name: Address: City: State: Zip: Dues: Pubs: Total: OKCancel Membership Form Name: Address: City: State: Zip: Pubs: Total: OK Cancel

71 Simple Complex Size: Uniformity: Height: Width: Preserve Proportions % of original % of original Size:: Preserve Proportions % of original height % of original width

72 Groupings Use visual arrangements to provide functional groupings of screen elements –Align elements in a group –Evenly space elements in a group –Provide separation between groups Use additional group elements sparingly –color & borders add complexity

73 Similar elements aligned vertically Vertical distance between similar objects small Membership Form Name: Address: City: State: Zip: Dues: Pubs: Total: OKCancel Simple Grouping

74 Boxes add additional complexity to form Spatial arrangement adequate Membership Form Name: Address: City: State: Zip: Dues: Pubs: Total: OKCancel Boxed Grouping

75 Background Grouping Membership Form Name: Address: City: State: Zip: Dues: Pubs: Total: OKCancel Color adds additional visual complexity Spatial arrangement adequate

76 Alignment Grids and the Users Logical Path Align labels. Labels for controls stacked vertically should be aligned with each other; left-justification is easier for users to scan than right justification, although the latter may look visually cleaner-if the input forms are the same size. (Otherwise, you get a Christmas tree, ragged-edge effect on the left and right.) Align within a set of controls. A related group of check boxes, radio buttons, or text fields should be aligned according to a regular grid. Align across controls. Aligned controls (as described previously) that are grouped together with other aligned controls should all follow the same grid. Follow a regular grid structure for larger-scale element groups, panes, and screens, as well as for smaller grouping of controls. Alan Cooper, Robert M. Reimann. About Face 2.0: The Essentials of Interaction Design. (Wiley, 2003). Page 230.

77 Aligned grid layout

78 Screen-based Controls Widgets –elements of screen displays –interaction toolkits –ready-made interaction objects –predefined behaviors –customizable properties

79 Functions of Widgets Selecting options and commands Entering and editing data values Displaying data

80 Kinds of Widgets Buttons Text entry/read-only Selection Combination entry/selection Specialized or custom Presentation

81 Design issues Labels and graphics Layout and organization Activation

82 Labels and Graphics Use labels and captions –Use standard names when appropriate –Use regular system font –Clearly tie the text to the control Maintain consistent heights and widths –Use common shapes (mostly rectangles) Pick icons that map to the actions –Supplement icons with text descriptions OK

83 Layout and Organization Provide adequate spacing Limit the number of controls on one screen Keep related controls together –Use visual enclosure of groups where appropriate

84 Aligning list boxes Align list boxes vertically rather than horizontally. Horizontally aligned list boxes are more difficult for the user to use, as the controls cannot be scanned easily.

85 Aligning radio buttons This : Not this:

86 Activation Provide keyboard equivalents –Control activation –Movement among controls within a screen Provide feedback for actions Gray out unavailable choices

87 Buttons Initiates an action –to activate a command (an alternate to menu choice or command line entry). –to display another window or menu selection Always visible –provides convenient access to frequently-used commands –standard shapes and screen location for similar commands. –Logical organization

88 Buttons Types –Command buttons -- text as labels –Bar buttons (menu buttons) -- graphics and/or text as labels –Radio buttons Next Microsofts Button Types

89 Which one is better? Plan Choice: LimitedBasicSuperiorPremium Plan Choice: Limited Basic Superior Premium Limited Basic Superior Premium Plan Choice

90 Button Design Issues Labels Shapes and Graphics Location and layout Organization Activation

91 Buttons -- labels Use standard button labels when available Provide meaningful action description Use regular system font –unless for some special purposes Center the label text Provide consistency across all screens

92 Buttons --shape and graphics Use rectangular shape whatever possible Maintain consistent button heights and widths Design graphics/icons that have natural mapping to the actions Enhanced graphics with text description

93 Buttons -- Organization Maintain consistency in button locations across screens and windows provide adequate spacing between buttons and other screen controls Restrict the number of buttons on one screen Follow standards Keep related buttons together

94 Buttons -- Activation Consider different actions for –mouse enter/exit.. mouse down/up/ Consider keyboard equivalents for actions Provide feedback for actions –highlight the button when the button is selected Gray out unavailable choices.

95 Text Entry/Read-Only Controls Text boxes –Editable/read-only (fields vs. labels) –single line/multiple lines –fixed size/resizable –fixed length/variable lengths –visual box/non-visual box –scrollable /non-scrollable Properties –background/foreground colors –sizes/fonts/styles of text –alignments

96 Text Box Design Provide descriptive caption Logical arrangement of multiple fields Consider the cursor movement from one field to another. Provide large enough boxes for fixed- length data Select reasonable fonts/sizes/colors Design highlight to attract attention

97 Selection Controls Present all options or choices on the screen –Radio Buttons –Check Boxes –Palettes –List Boxes –Combo Boxes Drop-Down/Pop-Up Single Selection/Multiple Selection?

98 Selection Design Choice Description –Meaningful and clear description for the value or effects of the choice –Use single line of text whenever possible Organization –Meaningful order of choices –Consider adding a enclosure box Activation –Provide visual feedback –Provide default values

99 List Box or Combo Box? List box –unlimited number of choices –possible multiple choices –consumes screen space –can be set to different size –easy to see the choices Combo box –unlimited number of choices –highlight the selection –conserves screen space –Extra step to display all the choices

100 More Selection Controls Spin Boxes Attached Combo Boxes 0.5 Left Margin: Font Style: Regular Italic Bold Bold Italic Regular

101 Other Controls Scroll Bars Sliders Toggle Switches Tab pages –Contain tabbed divider pages

102 Presentation Controls Provide additional information to screen elements –Tooltips a small popup window attached to an object shows only when the mouse moves over the object –Static Text Fields -- labels –Group Boxes Combined controls in one box –Progress Indicators

103 Message Design

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