friday, december 17 th , 2010

Comparing Handheld and Voice-Control

Interfaces When Using Mobile Phones and Portable Music

PlayersFriday, December 17th, 2010

Justin M. OwensShane B. McLaughlinJeremy Sudweeks

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Introduction

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IntroductionMethodologyProceduresAnalysisResultsConclusions

Background: Increasing number of electronic devices used in vehicles, requiring drivers take eyes off road.

Purpose: Determine whether a voice-control system offers driving performance advantages over manual control of mobile phones and music players.

Conducted on public, rural 65 mph roadway.

Tested 21 regular users of the voice-control system to avoid practice effects; younger (~20’s) and older (~40’s) age groups.

SYNC Voice-Control System

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System allows voice commands for dialing (“Call John Doe”) & MP3 track selection (“Play track Enter Sandman”), handsfree conversation

Also implements text-to-speech text message reception and canned message sending*

Experimental Design

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AgeYounger

Older

ModalityHandheld

SYNC

Task(Baseline)

Dial ContactConversation

Play Track

BetweenSubjects

WithinSubjects

Dependent Variables Task Duration

First -> Last task-related movement

Task-Related Interior Glances Number of Glances Glance Duration

Steering Measures Steering Variance Max Steering Wheel Speed

Mental Demand 1-7; Subscale of NASA TLX

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Test Vehicle 2010 Mercury Mariner with

SYNC®

VTTI Instrumentation Four cameras Cabin audio Accelerometers Gyros Forward radar CAN connectivity for

Steering wheel angle Speed Brake on/off

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Handheld Devices Participants used personal mobile phone and

portable music players for the handheld trials.

Phones: 10 - Numeric physical keyboards 7 - Touch screens 4 - QWERTY keypads

Music Players: 12 - Apple iPods with click-wheel 4 - Touch screen (2 iPhones and 1 iPod Touch) 5 - Other interfaces, including 1 Zune

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Testing Procedures 1.9 miles, 65 mph Completed 6 laps One task per leg,

after participant reached comfortable speed

Two trials each Handheld Dial Handheld Play Handheld Converse Voice Dial Voice Play Voice Converse

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Task

Task

Analysis

Video analyzed by trained reductionists

Separate General Linear Models were conducted for all measures.

Post-hoc comparisons conducted using Tukey correction.

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VehicleMATLABMS SQL MS SQL

Video Reduction

http://www.sas.com/index.html

Phone/MP3: Total Interior Glance Duration

Handheld Dial, Play had longer total eyes-interior duration than any other condition, including Baseline.

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0

5

10

15

20

25

30

Younger

Older

Dial Contact Play Track ConversationBase-line

A AA AA

B

C

0

0.5

1

1.5

2

2.5

3

Baseline Handheld Voice Handheld Voice Handheld Voice

Stee

ring

Varia

nce

(deg

)Younger

Older

Dial Contact Play Track ConverseBase-line

AA

A A

BB

A

Phone/MP3: Steering Variance

Handheld Dial, Handheld Play higher steering variance than all conditions except each other.

Differences not found between Voice and Baseline. Older drivers had more variance.

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Results

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Handheld dialing and music selection resulted in: Longer time to complete tasks More interior glances Longer total glance duration More steering variability Faster (jerkier) steering corrections

All tasks had higher reported mental demand than baseline, but handheld tasks were rated the highest.

Voice control and conversation rarely differed from baseline measures.

Conclusions Voice-control for placing calls and selecting tracks

had less impact on driving than manual control.

No performance differences were found between voice and manual tasks during conversations.

In general, measures during conversation were not found to be different from baseline driving.

Older drivers had more difficulty during manual dialing and track selection.

All tasks had higher reported mental demand than baseline, but handheld dialing/music were highest


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Acknowledgments & References Thanks to Ford Motor Company for funding

and test vehicle. John Shutko, point of contact

Owens, J.M., McLaughlin, S.B., & Sudweeks, J. (2010). On-Road comparison of driving performance measures when using handheld and voice-control interfaces for mobile phones and portable music players. SAE Int. J. Passeng. Cars – Mech. Syst. 3(1): 734-743.

*Owens, J.M., McLaughlin, S.B., & Sudweeks, J. (In Press), Driver performance while text messaging using handheld and in-vehicle systems. Accid. Anal. Prev., doi:10.1016/j.aap.2010.11.019

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Questions?

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Summary: Comparison to Baseline

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Task Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Hand

held

SYN

C

Dial na na - - - - - - - -- -Play na na -- -- -- -- - - - -- -- -

Converse na na - -- -Receive Text na na - - - -

Send Text na na -- - -- - -- - -- - - -- - -- -

No difference found between - Difference found-- Larger difference found

Max SW Velocity

Number of SW

reversals

Subjective Mental

DemandTask

Duration

Total Duration

of Interior Glances

Number of Interior

Glances

Maximum Duration Interior Glance

Mean Interior Glance

DurationSteering Variance

p < 0.05

Summary: Voice compared to Handheld

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p < 0.05

TaskTask

Duration

Total Duration of

Interior Glances

Number of Interior Glances

Maximum Duration Interior Glance

Mean Interior Glance

DurationSteering Variance

Max Steering Wheel

Velocity

Number of Steering Wheel

Reversals

Subjective Mental

DemandDial S S S S S S S S SPlay S S S S S S S S S

Converse NA SReceive Text S S S S S S S

Send Text S S S S S S S

SYNC Better Manual Better No difference found

friday, december 17 th , 2010

Documents

voicecontrol interfaces

music selection

handheld trials

voice commands

portable music playersfriday

steering variancehandheld

total eyesinterior duration

lapsone task