Comparing Handheld and Voice-Control Interfaces When Using Mobile Phones and Portable Music Players Friday, December 17 th, 2010 Justin M. Owens Shane B. McLaughlin Jeremy Sudweeks 1

Introduction 2 Introduction Methodology Procedures Analysis Results Conclusions  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 3 Introduction Methodology Procedures Analysis Results Conclusions  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 4 IntroductionMethodology Procedures Analysis Results Conclusions Age Younger Older Modality Handheld SYNC Task (Baseline) Dial Contact Conversation Play Track Between Subjects Within Subjects

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 5 IntroductionMethodology Procedures Analysis Results Conclusions

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 6 IntroductionMethodology Procedures Analysis Results Conclusions

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 7 IntroductionMethodology Procedures Analysis Results Conclusions

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 8 Introduction MethodologyProcedures Analysis Results Conclusions Task

Analysis  Video analyzed by trained reductionists  Separate General Linear Models were conducted for all measures.  Post-hoc comparisons conducted using Tukey correction. 9 Introduction Methodology ProceduresAnalysis Results Conclusions Vehicle MATLABMS SQL Video Reduction

Phone/MP3: Total Interior Glance Duration  Handheld Dial, Play had longer total eyes-interior duration than any other condition, including Baseline. 10 Introduction Methodology Procedures AnalysisResults Conclusions

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. 11 Introduction Methodology Procedures AnalysisResults Conclusions

Results 12 Introduction Methodology Procedures AnalysisResults Conclusions  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 Introduction Methodology Procedures Analysis ResultsConclusions 13

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): *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: /j.aap

Questions? 15

Summary: Comparison to Baseline 16 p < 0.05

Summary: Voice compared to Handheld 17 p < 0.05