CS305: HCI in SW
Development
More on Detailed Design:
Layout
Hardware Choices
Combining UI Elements in a Design
• Hardware and SW elements together
make up a UI
• Layout: How elements are combined
Principles of Good Layout
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Create natural groupings
Separate currently active components
Emphasize important components
Use “white space” effectively (or:
separate components when appropriate)
5. Make controls visible
6. Balance aesthetics and usability
Comments on Layout Principles
• Create natural groupings
– Both commands/controls and information
displayed
– Is there a natural structure?
– Use color, fonts, separators etc.
• Separate Currently Active Components
– Help user focus on what they’re doing now.
– Can pick back up if interrupted
– Make things prominent by color, placement,…
Comments on Layout Principles
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Emphasize important components
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Use color, type, animations, etc.
Be selective
Use “white space” effectively (or: separate
components when appropriate)
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White-space in GUIs, physical space on physical
devices
Alternative to lines, colors
Supports grouping for perception
In physical devices, supports physical usability
Comments on Layout Principles
• Make controls visible
– Support recognition over recall
– Control must be obvious, but also the controls
function
– Consider conventions, consistency, …
• Balance aesthetics and usability
– Some say: “Looking pretty is half the battle”
– How important? What trade-offs?
Comments on Layout Principles
• Create natural groupings
– Both commands/controls and information
displayed
– Is there a natural structure?
– Use color, fonts, separators etc.
• Separate Currently Active Components
– Help user focus on what they’re doing now.
– Can pick back up if interrupted
– Make things prominent by color, placement,…
Gestalt Principles
• Gestalt psychologists: layout principles
• Proximity
– Users will associate things that are close together
• Similarity
– If two things have same shape, size, color, orientation, then
users will associate them
• Continuity
– We want to see things aligned into continuous lines and curves
• Closure
– We want to see simple closed forms (blocks, lines) rather than
random, distinct items
• Symmetry
– We see regions bounded by symmetrical borders as a coherent
thing
Hardware for Interaction
• Do you really have choices here?
– Maybe you’re just writing for a PC’s windowed
interface
– Maybe you’re designing a handheld device
• General or for specialized users
• Still… you may have choices here
– Choice of typing vs. mouse movement
– Development on Tablet PCs
– Handhelds: wheels of various types, etc.
– Wiimote
Input Devices: Keyboards
• Keyboards
– Traditional computer keyboard not designed for
efficiency
– Alternatives: Dvorak, chord, kids, etc.
• See textbook for examples
• More interesting: smaller handhelds
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Do you need a keyboard?
Can you use “soft-keys” instead?
Size of buttons
Layout
Input Devices: Pointing Devices
• Continuous input devices
– Moving, dragging
– Keyboards are discrete input devices
• Indirect: mouse, joystick, trackball
• Direct: touch-screen, pen
• You may have choices:
– Example: touch-screen in kiosk etc.
– Must re-think ideas of buttons, menu, etc.
• Freed from many PC WIMP conventions
Are There Real Differences?
• See info on devices from p. 236 in UIDE text
– But read the caveats for this
– How would you evaluate different devices?
• Questions to ask:
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How important is learnability?
How important is accuracy?
How important is efficiency?
Environment: when and where used?
How much space is there?
User characteristics? Dexterity etc.
Tablet PC Issues
• Tablet PCs offer a familiar interface
– But with an fairly un-common input device
• Pen used for pointing, selecting, dragging
– Some examples next
• Ink input used for data-entry
– nothing on this today
• Article on website: The Challenge of
Designing Interfaces for the Tablet PC
Parallax
• Parallax
– Glass and display not
in same plane
– Your eye not always
properly aligned
• Consequence?
Solutions?
– Tell me.
Issues with Tablets and Menus
• Is it an issue if your user is left- or righthanded?
• For tablet PCs, can’t see through your
hand!
Sometimes Bigger Is Better
Fitts’ Law (Paul Fitts 1954)
• The law predicts that the time to point at an
object using a device is a function of the
distance from the target object & the object’s
size.
Time = a + b log (Dist/Size + 1)
• The further away & the smaller the object, the
longer the time to locate it and point.
• Useful for evaluating systems for which the
time to locate an object is important such as
handheld devices like mobile phones
Why oh why?
• What’s wrong with
Windows 2000’s
start button?
• Why are Mac apps
menu bars on the
top of the screen?
(next slide)
Interesting article on Fitts’ Law
Visit Tog’s website and do Tog’s quiz, designed to
give you fitts!
http://www.asktog.com/columns/022DesignedToGi
veFitts.html
Note this point: Screen edges effectively have
“infinite” depth. No need to slow down.
Corners…
Understand Fitts’ Law?
• Is there a benefit to having a label under the
icon on the Windows desktop?
• If you have an auto-hidden Taskbar on
Windows, how can this be irritating? Does
this confirm something about Fitts’ Law?
• Tweaking hierarchical pull-down menus –
how could this be done? Why an
improvement?
• How would Fitts’ law impact your layout of
buttons, fields, etc. in a dialog box?
Imagine Exercise
• You’re Tom Cruise in Minority Report!!!
– You have a BIG display and hand/pen inputs
• Got any clever ideas that use Fitts’ Law to
improve the interface?
Next:
• Guidance, guidelines
– “Guidance” means: rules, policies, standards
• “Softer” UI Components
Guidance for UI Design
•Other than textbook’s, other guidance
•Guidelines for physical design
• Nielsen’s heuristics
• Shneiderman’s eight golden rules
• Styles guides: commercial, corporate
•decide ‘look and feel’ for you
•widgets prescribed, e.g. icons,
toolbar
Usability principles (Nielsen 2001)
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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
Shneiderman’s 8 Golden Rules
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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
• Reduce short-term memory load
Other Guidance
• Commercial vendors guidelines
– Apple Macintosh
– Microsoft Windows
– Community: Java, OSF
• See Web site for links
• Also, international usability standards
UI Elements: Text and Color
• Lots we could talk about here
– We’ll cover text and color
Using Text Well
• Goal: legibility
• Font is typeface + size
• Factors to consider
– Sans serif better than serif on screen
– Not too big, not too small
• 10 or 12 point is smallest
– Extended chunks of bold or italic harder to read
– Spacing between lines
• Too much and lines don’t group in user’s mind
Using Text Well (2)
• Underlining: a web-link or emphasis?
– Consistency
– Common issue on web-pages
• Background / font-color combinations
– Black on white
– Lighter on darker (e.g. presentations in large
rooms)
– See page 254 in UIDE text
– Some you should avoid?
Can you read this easily?
Can you read this easily?
Can you read this easily?
Web Issues and Text
• Keep text to a minimum
– 50% of what you’d had in printed form
– Lists not paragraphs
• Help users scan for information
– Good headings and subheadings
– Highlight important things
– Good organization
• Divide long blocks into sections or pages
UI Elements: Color
• Reasons for using color:
– To draw attention
– To show status
– To make information clearer (like legibility)
– To make the UI more attractive
• The physics of color
– Saturation, brightness
– Differs on screen
– See text or other texts
Color Connotations
• Colors have connotations
– Cultural conventions
– What’s red mean in your culture?
• Danger?
• Joy, luck?
• Red state vs. blue state in US?
Labour vs. Conservative in Britain?
– Other colors:
• Green: nature or jealous, inexperienced
• Yellow: light/bright or caution
Class Exercise
• Information visualization
– measure something by unit in a larger thing
– E.g. word-frequency by chapter in a novel
– Goal: quickly see patterns of high/low
frequency
• Question: how could color be used?
– Issues, problems, ?
Color for Information
Representation
• Need to convey information?
– Color for emphasis
– Color for grouping
• Areas of the screen may have different background etc.
– Color coding (status)
– Perspective
• Dark/dim for background, brighter for foreground
– Layering: if data falls into layers
• Example: Look at simple apps like Microsoft
Windows’ calculator
– What colors are there? Why?