Download - Evaluating Touch Gesture Usability
Evaluating Touch
Gesture Usability
Kevin Arthur
Synaptics
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UPA 2010
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Multi-Finger TouchPad Gestures
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Two-Finger
Pinch ZoomTwo-Finger
RotateThree-Finger
Flick
Two-Finger
Scroll
Two-Finger
Pivot Rotate
Three-Finger
Press
Motivation for Testing Gestures
• Formative usability tests for feedback to developers
• Summative and competitive usability tests for sales, OEM partners
• Need for repeatable procedures
Audience
• Do users understand the gestures?
• Can users successfully perform the gestures?
• Are gestures satisfying to use?
Questions
• Holistic evaluation; test with users in a realistic scenario on a working system
• Different from pure data collection for testing gesture recognizer offline
Context
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Important Properties of Gestures
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• Gestures must be taught; testing the documentation is importantLack of Affordances
• Performance is not always predictable
• Recognition trade-offs exist between gestures in same parameter space
• Gestures should be evaluated as a set
Nondeterministic and Interdependent
• TouchPad’s primary use is still for pointing and scrolling; gestures shouldn’t interfere
Interface Overloading
• Hand size, long fingernailsUser Variation
Phases in Performing a Gesture
Exposure
Registration
Continuation
Termination
• Introduction through
documentation or prior use
• Initial touch contact and motion
for gesture recognition
• Gesture is registered and
“locked in” – mode switch
• Dynamic phase with relaxed
motion requirements
• End position, fingers lifting
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Test Framework
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Step Objective
1 Gesture IntroductionAssess understanding, help
materials
[Exposure phase]
Train to basic performance
[All phases]
2Familiarization and
Practice Task
3 Accuracy Task
Obtain rates of correct and incorrect
gesture recognition
[Registration phase]
4Satisfaction Questionnaire
and Debrief
Assess satisfaction, ease of use
[All phases]
Gesture Introduction
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Simulate new user experience
• “Out of box experience”
material
• Help videos
• Try the gesture until success
• If no success, moderator
assists
Familiarization and Practice Tasks:
Pinch Zoom
Zoom in on the South Residences, near the top of the map, and find the building called The Knoll. Zoom all the way in on The Knoll and then zoom all the way back out.
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2000 × 2000 pixels or higher.
Approximately five pinch-zooms
required.
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Flick and Rotate
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1. Use the rotate gesture to make the image upright.2. Type the image’s title into the caption field and press Enter.3. Use the flick gesture to go to the next image.
Flick and Rotate
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Accuracy Task
User performs a set number of gesture attempts
Moderator records table of system responses. Example:
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Gesture CorrectNo
Response
Misrecognized Other/
NotesAs Pinch As Rotate
Pinch Zoom
In7 2 - 1
Pinch Zoom
Out8 2 - 0
Rotate
Clockwise6 3 1 -
“requires
too large a
motion”
Rotate
Counter-
clockwise
7 1 2 -
Accuracy Results
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0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Pinch Zoom In
Pinch Zoom Out
Rotate CW Rotate CCW
Average
Misrecognized
No Response
Correct
Unified Measure
Accuracy Results, Competitive Study
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61
82
96
83
88
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2F Pinch Zoom
2F Rotate 3F Flick LR
3F Flick UD
2F Scroll
System AAverage Correct 82%
Correct No response Incorrect
94
73
85
94 96
90
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2F Pinch Zoom
2F Rotate 3F Flick LR
3F Flick UD
3F Press 2F Scroll
System BAverage Correct 89%
Correct No response Incorrect
Accuracy Results, Competitive Study
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98 62 92 97100 77 86 9797 68 93 1000
20
40
60
80
100
120
Pinch Rotate Flick Three-Finger Press
Co
rre
ct
(%)
Correct Gesture Recognition Rates
System A
System B
System C
Satisfaction Questionnaire
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Satisfaction Questionnaire
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Questionnaire Result
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7.38
4.38
7.88
8.75
8.25
1 2 3 4 5 6 7 8 9
Pinch
Rotate
3F Flick
3F Press
2F Scroll
I would use this gesture if it were available(strongly disagree = 1, strongly agree = 9)
Strongly
Disagree
Strongly
Agree
Questionnaire,
Competitive Rating Format
How well do the gestures work on each system?
Please rate from 1 (Poor) to 5 (Excellent)
Gesture System A System B System C
Pinch Zoom
Rotate N/A
Flick Left-Right
Flick Up-Down N/A
Three-Finger Press N/A N/A
Two-Finger Scrolling
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1
2
3
4
5
Pinch Zoom 2F Rotate 1F Rotate (Chiral)
Flick LR Flick UD 1F Scroll (Linear)
1F Scroll (Circular)
2F Scrolling
User Ratings With 95% Confidence Intervals
System A System B System C
Ratings Results
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Excellent
Poor
Related Tests & Gesture Side-Effects
Other usability tests for notebook input devices
• Pointing (target acquisition)
• Drag and drop
• Scrolling
• Typing and accidental TouchPad input
Assess gesture side-effects
• Unintended gestures
• Other issues
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Conclusions
Properties of gestures call for careful testing
• Gesture introduction and documentation is key
• Gestures are nondeterministic – less predictable
• Gestures are interdependent; test as a set
Framework of gesture tests
1. Gesture Introduction
2. Familiarity and Practice Tasks
3. Accuracy Tasks
4. Satisfaction Questionnaire and Debrief
5. Related Tests & Gesture Side-Effects
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Resources
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References
• Sylvia Le Hong and Dan Mauney, “Cultural Differences and Similarities
in the Use of Gestures on Touchscreen User Interfaces,” UPA 2010. blog.humancentric.com/gesture-research/
• Mark Billinghurst and Bill Buxton, “Gesture Based Interaction” in Human
Input to Computer Systems (draft), www.billbuxton.com/inputManuscript.html
• Dan Saffer, Designing Gestural Interfaces, O’Reilly 2008.
• Craig Villamor, Dan Willis, Luke Wroblewski, Touch Gesture Reference
Guide, www.lukew.com/touch/
• Jacob Wobbrock , Meredith Ringel Morris, Andrew Wilson, “User-
Defined Gestures for Surface Computing,” CHI 2009.
• Mike Wu, Chia Shen, Kathy Ryall, Clifton Forlines, Ravin Balakrishnan,
“Gesture Registration, Relaxation, and Reuse for Multi-Point Direct-
Touch Surfaces,” IEEE Tabletop 2006.
Contact
• [email protected], touchusability.com
Acknowledgments
• Usability colleagues at Dell, HP, Lenovo, Synaptics