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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

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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

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4500

DesktopDriving

Audio Visual Dual

1 20

500

1000

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DesktopDriving

Response time: menu style

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PRadial Linear

0.0

0.1

0.2

0.3

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0.5

0.6

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Audio Visual Dual

Late

ral V

eloc

ity

(m/s

)Lateral velocity

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0

10

20

30

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50

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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