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3. Interaction Performance
• 60s vs. Today
– Performance
• Hz -> GHz
– Memory
• k -> GB
– Storage
• k -> TB
– Input
• punch cards ->
• Keyboards, Pens, tablets, mobile
phones, mice, digital cameras, web
cams
– Output
• 10 character/sec
• Megapixel displays, color laser,
surround sound, force feedback, VR
• Substantial bandwidth increase!
4. Interaction Performance
• Future?
– Gestural input
– Two-handed input
– 3D I/O
– Others: voice, wearable, whole
body, eye trackers, data gloves,
haptics, force feedback
– Engineering research!
– Entire companies created around
one single technology
• Current trend:
– Multimodal (using car navigation
via buttons or voice)
– Helps disabled (esp. those w/
different levels of disability)
5. Keyboard and Keypads
• QWERTY keyboards been
around for a long time
– (1870s – Christopher Sholes)
– Cons: Not easy to learn
– Pros: Familiarity
– Stats:
• Beginners: 1 keystroke per sec
• Average office worker: 5
keystrokes (50 wpm)
• Experts: 15 keystrokes per sec
(150 wpm)
• Is it possible to do better?
Suggestions?
6. Keyboard and Keypads
• Look at the piano for possible
inspiration
• Court reporter keyboards (one
keypress = multiple letters or a
word)
– 300 wpm, requires extensive
training and use
• Keyboard properties that matter
– Size
• large - imposing for novices,
appears more complex
• mobile devices
– Adjustable
• Reduces RSI, better performance
and comfort
– Mobile phone keyboards,
blackberry devices, etc.
7. Keyboard Layouts• QWERTY
– Frequently used pairs far apart
– Fewer typewriter jams
– Electronic approaches don’t jam.. why use
it?
• DVOARK (1920s)
– 150 wpm->200 wpm
– Reducing errors
– Takes about one week to switch
– Stops most from trying
• ABCDE – style
– Easier for non-typists
– Studies show no improvement vs. QWERTY
• Number pads
– What’s in the top row?
– Look at phones (slight faster), then look at
calculators, keypads
• Those for disabled
– Split keyboards
– KeyBowl’s orbiTouch (screenshot)
– Eyetrackers, mice
– Dasher - 2d motion with word prediction
8. Keys
• Current keyboards have been
extensively tested
– Size
– Shape
– Required force
– Spacing
• Speed vs. error rates for majority
of users
• Distinctive click gives audio
feedback
– Why membrane keyboards are
slow (Atari 400?)
• Environment hazards might
necessitate
• Usually speed is not a factor
9. Keys Guidelines
• Special keys should be denoted
• State keys (such as caps, etc.)
should have easily noted states
• Special curves or dots for home
keys for touch typists
• Inverted T Cursor movement keys
are important (though cross is
easier for novices)
• Auto-repeat feature
– Improves performance, but only if
repeat is customizable (motor
impaired, young, old)
• Two thinking points:
– Why are home keys fastest to
type?
– Why are certain keys larger?
(Enter, Shift, Space bar)
• This is called Fitt’s Law
10. Keypads for small devices
• PDAs, Cellphones, Game consoles
• Fold out keyboards
• Virtual keyboard
• Cloth keyboards (ElekSen)
• Haptic feedback?
• Mobile phones
– Combine static keys with dynamic soft keys
– Multi-tap a key to get to a character
– Study: Predictive techniques greatly improve
performance
– Ex. LetterWise = 20 wpm vs 15 wpm multitap
• Draw keyboard on screen and tap w/ pen
– Speed: 20 to 30 wpm (Sears ’93)
• Handwriting recognition (still hard)
– Subset: Graffiti2 (uses unistrokes)
11. Pointing Devices
• Direct manipulation needs some pointing device
• Factors:
– Size of device
– Accuracy
– Dimensionality
• Interaction Tasks:
– Select – menu selection, from a list
– Position – 1D, 2D, 3D (ex. paint)
– Orientation – Control orientation or provide direct 3D
orientation input
– Path – Multiple poses are recorded
• ex. to draw a line
– Quantify – control widgets that affect variables
– Text – move text
• Faster w/ less error than keyboard
• Two types (Box 9.1)
– Direct control – device is on the screen surface
(touchscreen, stylus)
– Indirect control – mouse, trackball, joystick, touchpad
12. Direct-control pointing
• First device – lightpen
– Point to a place on screen and press a
button
– Pros:
• Easy to understand and use
• Very fast for some operations (e.g. drawing)
– Cons:
• Hand gets tired fast!
• Hand and pen blocks view of screen
• Fragile
• Evolved into the touchscreen
– Pros: Very robust, no moving parts
– Cons: Depending on app, accuracy could
be an issue
• 1600x1600 res with acoustic wave
– Must be careful about software design for
selection (land-on strategy).
• If you don’t show a cursor of where you are
selecting, users get confused
– User confidence is improved with a good
lift-off strategy
13. Direct-control pointing
• Primarily for novice users
or large user base
• Case study: Disney World
• Need to consider those
who are: disabled,
illiterate, hard of
hearing, errors in usage
(two touch points), etc.
14. Indirect-Control Pointing
• Pros:
– Reduces hand-fatigue
– Reduces obscuration problems
• Cons:
– Increases cognitive load
– Spatial ability comes more into play
• Mouse
– Pros:
• Familiarity
• Wide availability
• Low cost
• Easy to use
• Accurate
– Cons:
• Time to grab mouse
• Desk space
• Encumbrance (wire), dirt
• Long motions aren’t easy or obvious (pick up and replace)
– Consider, weight, size, style, # of buttons, force feedback
15. Indirect-Control Pointing
• Trackball
– Pros:
• Small physical footprint
• Good for kiosks
• Joystick
– Easy to use, lots of buttons
– Good for tracking (guide or
follow an on screen object)
– Does it map well to your app?
• Touchpoint
– Pressure-sensitive ‘nubbin’ on
laptops
– Keep fingers on the home
position
16. Indirect-Control Pointing
• Touchpad
– Laptop mouse device
– Lack of moving parts, and
low profile
– Accuracy, esp. those w/
motor disabilities
• Graphics Tablet
– Screen shot
– comfort
– good for cad, artists
– Limited data entry
17. Comparing pointing devices
• Direct pointing
– Study: Faster but less accurate than indirect (Haller ’84)
• Lots of studies confirm mouse is best for most tasks for speed
and accuracy
• Trackpoint < Trackballs & Touchpads < Mouse
• Short distances – cursor keys are better
• Disabled prefer joysticks and trackballs
– If force application is a problem, then touch sensitive is preferred
– Vision impaired have problems with most pointing devices
• Use multimodal approach or customizable cursors
• Read Vanderheiden ’04 for a case study
• Designers should smooth out trajectories
• Large targets reduce time and frustration
20. Fitts’s Law
• Paul Fitts (1954) developed a model of human hand
movement
• Used to predict time to point at an object
• What are the factors to determine the time to point to an
object?
– D – distance to target
– W – size of target
• Just from your own experience, is this function linear?
– No, since if Target A is D distance and Target B is 2D distance,
it doesn’t take twice as long
– What about target size? Not linear there either
• MT = a + b log2(D/W + 1)
– a = time to start/stop in seconds (empirically measured
per device)
– b = inherent speed of the device (empirically measured
per device)
– Ex. a = 300 ms, b = 200 ms/bit, D = 14 cm, W = 2 cm
• Ans: 300 + 200 log2(14/2 + 1) = 900 ms
– Really a slope-intercept model
21. Fitts’s Law
• MT = a + b log2(D/W + 1)
– a = time to start/stop in seconds (empirically measured per
device)
– b = inherent speed of the device (empirically measured per
device)
– Ex. a = 300 ms, b = 200 ms/bit, D = 14 cm, W = 2 cm
• Ans: 300 + 200 log2(14/2 + 1) = 900 ms
– Question: If I wanted to half the pointing time (on average), how much
do I change the size?
• Proven to provide good timings for most age groups
• Newer versions taken into account
– Direction (we are faster horizontally than vertically)
– Device weight
– Target shape
– Arm position (resting or midair)
– 2D and 3D (Zhai ’96)
22. Very Successfully Studied
• Applies to
– Feet, eye gaze, head mounted sights
– Many types of input devices
– Physical environments (underwater!)
– User populations (even retarded and drugged)
– Drag & Drop and Point & Click
• Limitations
– Dimensionality
– Software accelerated pointer motion
– Training
– Trajectory Tasks (Accot-Zhai Steering Law)
– Decision Making (Hick’s Law)
• Results (what does it say about)
– Buttons and widget size?
– Edges?
– Popup vs. pull-down menus
– Pie vs. Linear menus
– iPhone/web pages (real borders) vs. monitor+mouse (virtual borders)
• Interesting readings:
– http://particletree.com/features/visualizing-fittss-law/
– http://www.asktog.com/columns/022DesignedToGiveFitts.html
– http://www.yorku.ca/mack/GI92.html
23. Precision Pointing Movement Time
• Study: Sears and Shneiderman ’91
– Broke down task into gross and fine components for small targets
– PPMT = a + b log2(D/W+1) + c log2(d/W)
• c – speed for short distance movement
• d – minor distance
– Notice how the overall time changes with a smaller target.
• Other factors
– Age (Pg. 369)
• Research: How can we design devices that produce smaller
constants for the predictive equation
– Two handed
– Zooming
24. Novel Devices
• Themes:
– Make device more diverse
• Users
• Task
– Improve match between task and
device
– Improve affordance
– Refine input
– Feedback strategies
• Foot controls
– Already used in music where
hands might be busy
– Cars
– Foot mouse was twice as slow as
hand mouse
– Could specify ‘modes’
25. Novel Devices
• Eye-tracking
– Accuracy 1-2 degrees
– selections are by constant
stare for 200-600 ms
– How do you distinguish w/ a
selection and a gaze?
– Combine w/ manual input
• Multiple degree of freedom
devices
– Logitech Spaceball and
SpaceMouse
– Ascension Bird
– Polhemus Liberty and IsoTrack
26. Novel Devices
• Boom Chameleon
– Pros: Natural, good spatial
understanding
– Cons: limited applications, hard
to interact (very passive)
• DataGlove
– Pinch glove
– Gesture recognition
– American Sign Language,
musical director
– Pros: Natural
– Cons: Size, hygiene, accuracy,
durability
27. Novel Devices
• Haptic Feedback
– Why is resistance useful?
– SensAble Technology’s Phantom
– Cons: limited applications
– Sound and vibration are easier and can
be a good approximation
• Rumble pack
• Two-Handed input
– Different hands have different
precision
– Non-dominant hand selects fill, the
other selects objects
• Ubiquitous Computing and Tangible
User Interface
– Active Badges allows you to move
about the house w/ your profile
– Which sensors could you use?
– Elderly, disabled
– Research: Smart House
– Myron Kruger – novel user
participation in art (Lots of exhibit art
at siggraph)
28. Novel Devices
• Paper/Whiteboards
– Video capture of annotations
– Record notes (special tracked pens
Logitech digital pen)
• Handheld Devices
– PDA
– Universal remote
– Help disabled
• Read LCD screens
• Rooms in building
• Maps
– Interesting body-context-sensitive.
• Ex. hold PDA by ear = phone call
answer.
29. Novel Devices
• Miscellaneous
– Shapetape – reports 3D
shape.
• Tracks limbs
• Engineer for specific app
(like a gun trigger
connected to serial port)
– Pros: good affordance
– Cons: Limited general use,
time
30. Speech and Auditory Interfaces
• There’s the dream
• Then there’s reality
• Practical apps don’t really require freeform
discussions with a computer
– Goals:
• Low cognitive load
• Low error rates
• Smaller goals:
– Speech Store and Forward (voice mail)
– Speech Generation
– Currently not too bad, low cost, available
31. Speech and Auditory Interfaces
• Bandwidth is much lower than visual displays
• Ephemeral nature of speech (tone, etc.)
• Difficulty in parsing/searching (Box 9.2)
• Types
– Discrete-word recognition
– Continuous speech
– Voice information
– Speech generation
– Non-speech auditory
• If you want to do research here, lots of research in the audio,
audio psychology, and DSP field you should understand
32. Discrete-Word Recognition
• Individual words spoken by a specific person
• Command and control
• 90-98% for 100-10000 word vocabularies
• Training
– Speaker speaks the vocabulary
– Speaker-independent
• Still requires
– Low noise operating environment
– Microphones
– Vocabulary choice
– Clear voice (language disabled are hampered, stressed)
– Reduce most questions to very distinct answers (yes/no)
33. Discrete-Word Recognition
• Helps:
– Disabled
– Elderly
– Cognitive challenged
– User is visually distracted
– Mobility or space restrictions
• Apps:
– Telephone-based info
• Study: much slower for cursor movement than mouse or keyboard
(Christian ’00)
• Study: choosing actions (such as drawing actions) improved performance
by 21% (Pausch ’91) and word processing (Karl ’93)
– However acoustic memory requires high cognitive load (> than hand/eye)
• Toys are successful (dolls, robots). Accuracy isn’t as important
• Feedback is difficult
34. Continuous Speech Recognition
• Dictation
• Error rates and error repair are still poor
• Higher cognitive load, could lower overall quality
• Why is it hard?
– Recognize boundaries (normal speech blurs them)
– Context sensitivity
– “How to wreck a nice beach”
• Much training
• Specialized vocabularies (like medical or legal)
• Apps:
– Dictate reports, notes, letters
– Communication skills practice (virtual patient)
– Automatic retrieval/transcription of audio content (like radio, CC)
– Security/user ID
35. Voice Information Systems
• Use human voice as a source of info
• Apps:
– Tourist info
– Museum audio tours
– Voice menus (Interactive Voice Response IVR systems)
• Use speech recognition to also cut through menus
– If menus are too long, users get frustrated
– Cheaper than hiring 24 hr/day reps
• Voice mail systems
– Interface isn’t the best
• Get email in your car
– Also helps with non-tech savvy like the elderly
• Potentially aides with
– Learning (engage more senses)
– Cognitive load (hypothesize each sense has a limited ‘bandwidth’)
• Think ER, or fighter jets
36. Speech Generation
• Play back speech (games)
• Combine text (navigation systems)
• Careful evaluation!
– Speech isn’t always great
• Door is ajar – now just a tone
• Use flash
• Supermarket scanners
– Often times a simple tone is better
– Why? Cognitive load
• Thus cockpits and control rooms need speech
• Competes w/ human-human communication
37. Speech Generation
• Ex: Text-to-Speech (TTS)
• Latest TTS uses multiple syllabi to make generated speech sound better
– Robotic speech could be desirable to get attention
– All depends on app
– Thus don’t assume one way is the best, you should user test
• Apps: TTS for blind, JAWS
• Web-based voice apps: VoiceXML and SALT (tagged web pages).
– Good for disabled, and also for mobile devices
• Use if
– Message is short
– Requires dynamic responses
– Events in time
• Good when visual displays aren’t that useful. When?
– Bad lighting, vibrations (say liftoff)
38. Non-speech Auditory Interface
• Audio tones that provide information
• Major Research Area
– Sonification – converting information into audio
– Audiolization
– Auditory Interfaces
• Browsers produced a click when you clicked on a link
– Increases confidence
– Can do tasks without visual cognitive load
– Helps figure out when things are wrong
– Greatly helps visually impaired
39. Non-speech Auditory Interface
• Terms:
– Auditory icons – familiar sounds
(record real world sound and play
it in your app)
– Earcons – new learned sounds
(door ajar)
• Role in video games is huge
– Emotions, Tension, set mood
• To create 3D sound
– Need to do more than stereo
– Take into account Head-related
transfer function (HRTF)
• Ear and head shape
• New musical instruments
– Theremin
• New ways to arrange music
40. Displays
• Primary Source of feedback
• Properties:
– Physical Dimension
– Resolution
– Color Depth and correctness
– Brightness, contrast, glare
– Power
– Refresh rate
– Cost
– Reliability
– # of users
41. Display Technology
• Monochrome displays (single
color)
– Low cost
– Greater intensity range (medical)
• Color
– Raster Scan CRT
– LCD – thin, bright
– Plasma – very bright, thin
– LED – large public displays
– Electronic Ink – new product w/
tiny capsules of negative black
particles and positive white
– Braille – refreshable cells with
dots that rise up
42. Large Displays
• Wall displays
– Informational
• Control rooms, military, flight
control rooms, emergency
response
• Provides
– System overview
– Increases situational awareness
– Effective team review
• Old: Array of CRTs
– Interactive
• Require new interaction methods
(freehand sketch, PDAs)
• Local and remote collaboration
• Art, engineering
43. Large Displays
• Multiple Desktop Displays
– Multiple CRTs or Flat panels for
large desktops
– Cheap
– Familiar
– Spatial divide up tasks
– Comparison tasks are easier
– Too much info?
• HMD
• Eventually -> Every surface a pixel
44. Mobile device displays
• Applications
– Personal
• Reprogrammable picture
frames
– Digital family portrait
(GaTech)
– Business
• PDAs, cellphones
– Medical
• Monitor patients
– Research: Modality Translation
Services (Trace Center –
University of Wisconsin)
• As you move about it auto
converts data, info, etc. for
you
45. Mobile device displays
• Actions on mobile devices
– Monitor information and alert
(calendar)
– Gather then spread out
information (phone)
– Participate in groups and relate
to individual (networked
devices)
– Locate services and identify
objects (GPS car system)
– Capture and then share info
(phone)
46. Mobile device displays
• Guidelines for design
– Bergman ’00, Weiss, ’02
– Industry led research and design case studies
(Lindholm ’03)
– Typically short in time usage (except handheld
games)
– Optimize for repetitive tasks (rank functions by
frequency)
– Research: new ways to organize large amounts of
info on a small screen
– Study: Rapid Serial Visual Presentation (RSVP)
presents text at a constant speed (33%
improvement Oquist ’03)
– Searching and web browsing still very poor
performance
– Promising: Hierarchical representation (show full
document and allow user to select where to zoom
into)
47. Animation, Image, and Video
• Content quality has also greatly
increased
• 3D rendering is near life-like
• Digital Photography is common
• Scanned documents
• Video compression
• Multimedia considerations for the
disabled
• Printers
– 3D Printers create custom objects from
3D models
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