1 shengdong zhao department of computer science university of toronto july 9, 2008 earpod:...
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Shengdong ZhaoDepartment of Computer Science
University of TorontoJuly 9, 2008
earPod: Efficient, Hierarchical, Eyes-free Menu Selection
Outline• Research problem • Previous research• Research questions• Research strategy and focus• Prototype• Empirical studies• Contributions• Future work
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Research problems and objectives
• Motivating problem– How can users interact with information devices in mobile
environments when their visual attention is taken up by other tasks (e.g navigation through the environment)
• Objective– To develop interactive techniques that support user
control and feedback without relying on the visual modality
• Scope – This research focuses on menu selection because this is an
elemental task (Foley et al. ‘84)
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Previous research• Visual menus
– Linear menus (e.g., Sear and Schneiderman ’94; Cockburn and Gin ‘06, etc.)
– Radial menus (e.g., Callahan et al. ‘88; Kurtenbach ’93, etc.)
• Auditory applications– Accessibility for the blind (e.g., Edwards ‘89; Mynatt and Weber ‘94, etc.)
– Mobile auditory interfaces (e.g., Roy and Schmandt ‘96; Pirhonen et al. ’02, etc.)
• Auditory menus– Interactive Voice Response (IVR) systems (e.g., Marics and Engelbeck
1997; Resnick and Virzi ’92, etc.)
– Head gesture auditory pie menu (Brewster et al. ‘03)
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Research questions
• How to design usable eyes-free menus?– Designing interfaces with reasonable levels of
efficiency and ease of use – Facilitating a smooth novice to expert transition
• How to work around the problems with serial and temporal audio feedback?– Facilitating scan and compare of menu items– Providing users with a sense of control and
responsiveness5
Research strategy
• Define research problem• Review literature• Define general design concept• Perform iteratively design and pilot studies for
prototype• Conduct empirical studies to explore
prototype properties • Derive design recommendations based on
empirical results6
Selected input and output modalities
• Touch input– Combines relative and absolute pointing (Hinckley ‘01)
– Can be robustly operated in motion (Buxton et al. ‘85)
– Can be combined with other input devices (Hinckley and Sinclair ‘99; Rekimoto et al. ‘03)
• Auditory feedback– The other primary remote sense (Gaver ‘97)
– The only other sense with a natural language*
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earPod prototype
• A touch-sensitive device with software to perform eyes-free, hierarchical menu selection
• earPod prototype used commercial touchpad augmented with custom-built plastic cover, with cable to computer for voice output
• Built in University of Toronto in 2006 with Pierre Dragicevic
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earPod Prototype
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earPod interaction
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Novice Intermediate
Intermediate Expert
Video - browsing
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Video - fast browsing
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Video - very fast browsing
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Video - expert use
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Prototype design• Efficiency
– By-pass audio – Use interruptible audio feedback– Use non-speech audio
• Sense of control – Synchronous communication (reactive audio feedback)
• Simplicity and power – Gliding and tapping
• Easy to learn– Use spatial audio to reinforce mental model – Self-discoverable transition
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Empirical studies
Motivating questions: 1. How does earPod compare with a popular visual menu
selection technique used by iPod?
2. How does earPod compare with a number of competitor techniques with different modalities and menu styles?
3. What are learning behaviors for earPod and the related techniques?
4. How does earPod and the related techniques perform with a visually demanding primary task?
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Evaluation issues • Modality
– Visual
– Audio
– Dual
• Menu style– Linear
– Radial
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Menu Style
Radial (absolute) Linear (relative)
Modality
Audio Audio radial Audio linear
Visual Visual radial Visual linear
Dual Audio visual radial Audio visual linear
4 empirical studies
• 4 empirical studies were conducted at UofT in 2006-08
• Experiment 1: earPod vs. iPod (audio radial vs. visual linear)
• Experiment 2: 3 x 2 study (3 modalities x 2 menu styles)
• Experiment 3: 2 x 2 longitudinal study (audio linear, visual
linear, audio radial, visual radial) • Experiment 4: 3 x 2 dual-task study (3 modalities x 2 menu
styles)
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Experimental 1 design
• Goal: compare earPod with iPod-like linear menu
• 60-90 minute session, within-subject, counter-balanced
• Setup:12 participants x 2 techniques (audio and visual) x (40+80) items for the 2 menu configurations (8 and
8x8) x 4 blocks= 11,520 menu selections in total.
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Results: response time
Block number Block number
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Results: response time
Block number Block number
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Results: response time
Block number Block number
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Experiment 1 - results and discussion
• earPod has comparable performance with iPod-like linear menu
• earPod user performance improves more rapidly than that of iPod-like linear menu
• With practice, earPod can outperform iPod-like linear menu
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Experiment 2 design
• Goal: systematic investigation of modality of feedback and menu style
• 60-minute, within subject, counter-balanced • Setup
12 participants x6 techniques x8 menu items x13 blocks (12 blocks + 1 practice block)= 7488 menu selections in total
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Response time
Audio radial
Audio linear
Visual radial
Visual linear
Audio visual radial
Audio visual linear
Experiment 2 - results and discussion
• Accuracy– Comparable performance among all techniques
• Speed – visual radial ~ dual radial
< audio radial ~ visual linear ~ dual linear < audio linear
• Modality– Visual ~ dual < audio
• Menu style– Radial < linear
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Experiment 3: longitudinal study
Goal: learning of earPod and related techniques5 one-hour sessions in a week, between-subjectSetup:
2 participants (per technique) x 4 techniques x64 items for 1 menu configuration (8 x 8) x7 blocks per day x5 days= 17920 menu selections in total
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Accuracy
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1 2 3 4 50.88
0.9
0.92
0.94
0.96
0.98
1
Audio linear Audio radial Visual linear Visual radial
Day
Response time
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1 2 3 4 50
1000
2000
3000
4000
5000
6000
Audio linear Audio radial Visual linear Visual radial
Day
Gliding to tapping transition
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Items explored Tapping percentage
1 2 3 4 50
1
2
3
4
5
6
7
Audio linear Audio radial Visual linear Visual radial
1 2 3 4 50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Audio radial Visual radial
Day Day
Experiment 3 - results and discussion
• Novice performance is determined by modality, expert performance is determined by menu style
• Rapid learning is observed for earPod• Users can perform tapping for 70-80% of the
64 menu items from day 3 onwards• Audio linear has comparable performance
with visual linear from day 3 onwards
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Experiment 4: dual-task study
Goal: Investigate the properties of using earPod and the related techniques as a secondary task in a dual-task setting and their impact on the visually demanding primary task
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Experiment 4: dual-task study
• Dual-task– Primary task: simulated driving– Secondary task: menu selection
• External validity: similar settings have been
successfully used by Salvucci et al. ‘01, ‘02, ‘05
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Experiment 4 design
• Conditions– Desktop
• 12 participants X 6 techniques X 8 items of 1 menu configurations X (3 + 1) blocks = 2304 menu selections
– Driving• 12 participants X 6 techniques X 8 items of 1 menu configurations X (1 + 1)
blocks = 1152 menu selections
• Measures– Desktop
• Speed & accuracy of menu selection
– Driving• Speed & accuracy of menu selection (secondary task)• Driving performance (primary task)
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Experiment 4 setup
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Response time: modality
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1 2 30
500
1000
1500
2000
2500
3000
3500
4000
4500
DesktopDriving
Audio Visual Dual
1 20
500
1000
1500
2000
2500
3000
3500
4000
4500
DesktopDriving
Response time: menu style
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PRadial Linear
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Audio Visual Dual
Late
ral V
eloc
ity
(m/s
)Lateral velocity
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0
10
20
30
40
50
60
70
80
Audio Visual Dual
Follo
win
g D
ista
nce
(m
)Following distance
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Experiment 4 - results and discussion
• Audio techniques work better with a visually demanding primary task– Comparable performance with visual techniques,
less impact on primary tasks • Although dual-channel techniques have
similar performance with audio techniques, users prefer single channel audio feedback
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Summary of empirical studies
• earPod has comparable performance with visual linear menus
• Transition from novice to expert for earPod is fast
• Audio techniques work better with a visually demanding primary task
• Users only pay attention to the appropriate channel when are presented with both channels of feedback
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Contributions
• Developed a novel interaction technique called earPod
• Conducted empirical evaluations on earPod and related techniques
• Derived design recommendation for incorporating earPod and related techniques to mobile devices
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Future work
• Explore eyes-free menu techniques for long and dynamic lists
• Investigate the role of compression and dichotic listening
• Extend earPod to other mobile scenarios (e.g., walking, running, etc.)
• Develop eyes-free interaction techniques for other tasks and applications (e.g., drag & drop, text entry, etc.)
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Questions
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The End
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