Collision Warning Design To Mitigate Driver Distraction (CHI 2004)

1. Andrew Muller & Eugene Khokhlov Collision Warning DesignTo Mitigate Driver Distraction (CHI 2004) Collision Warning Design

2. John D. Lee Ph.D. Elizabeth Hayes Daimler Chrysler (Chewbacca) University of Iowa • Joshua D. Hoffman Grad Student Collision Warning Design

3. To The Point: • The Problem: Too many distractions while driving a car • The Need: Collision warning system Collision Warning Design

4. Background Information • In-vehicle Information Systems (IVIS) are now feasible because: • Technology Advances • Societal Trends • IVIS Functionality • Response Types • Critical Factors for IVIS Collision Warning Design

5. Alert Strategies • Warning Strategies • Graded • Single Staged • Sensor Modality Presentation • Haptic (touch) • Auditory Collision Warning Design

6. Experiment Goals • Experiment 1 • Examine how driver response depends on graded and single stage warnings • Examine how driver response depends on modality (haptic vs. auditory) of the warning • Experiment 2 • Examine how these warning strategies and modalities affect driver preference Collision Warning Design

7. Experiment 1 Method • A mixed between/within-subject experimental design • 3, 15-minute driving scenarios • 21 braking events (7x3)=21 • 3 levels of severity • Speech-based email system to distract the driver Collision Warning Design

8. Participants • 40 individuals • 20 female, 20 male • Ages of 25 and 55 (licensed) • Unaware of the nature of the research • Paid $20 each Collision Warning Design

9. Apparatus • Fixed-based, medium-fidelity driving simulator • 1992 Mercury Sable • 50-degree visual field of view • 640x480 screen • Visual collision warning icon • Needed elements for auditory and haptic alerts Collision Warning Design

10. DriveSafety (Hyperion) Collision Warning Design

11. Experimental Design and Independent Variables • Mixed between-within subject design • Between subject variables • Warning modality • Warning strategy • Within subject variables • Severity of lead vehicle breaking • If response was require Collision Warning Design

12. Dependent Variables • Safety benefit • Number of collisions • Adjusted minimum time to collision (AMTTC) • Driver response process (response followed by assessment or assessment followed by response) Collision Warning Design

13. Procedure • Operation instruction • Introductory drive (5 min) • 3 main drives (15 min/each) • 7 braking events per drive @ 55mph • 1/7 was severe, always at end • Complete auditory email task Collision Warning Design

14. Results • 741 data points total • Repeated-measures ANOVA was used to analyze the data using two-tailed hypothesis tests Collision Warning Design

15. Results – Severity of braking events and driver response • Drivers responded to braking events in a systematic and realistic manner • AMTTC reflected braking severity • Severity of lead vehicle braking affected drivers’ braking response • Severity of braking affected mean deceleration Collision Warning Design

16. Results – Interface characteristics and safety benefit (collisions) • 40 potential collisions • 10 collisions occurred • 7 in single-stage and 3 in graded • X2(1)= 2.13, p=0.144 • 5 in auditory and 5 in haptic Collision Warning Design

17. Results – Interface characteristics and safety benefit (AMTTC) • Slight benefit for graded compared to single-stage • F(1,36)=8.74, p=0.0055 • Graded substantially better in severe braking events Collision Warning Design

18. AMTTC Collision Warning Design

19. Response to nuisance alarm braking events Collision Warning Design

20. Experiment 2 Method • A within-subject experimental design • 4, 10-minute scenarios • 24 braking events • 3 levels of severity • 2/3 of events required no driver response Collision Warning Design

21. Participants • 20 individuals • 11 females, 9 males (licensed) • Between the ages of 25 and 55 • Unaware of the nature of the research • Paid $20 each Collision Warning Design

22. Apparatus & Independent variables and experimental design • Same as in experiment 1 Collision Warning Design

23. Dependent variables • Driver attitudes were measured with a series of subjective rating scales after each drive • After completion of all trials, they comparatively ranked the systems Collision Warning Design

24. Procedure • Operation instruction • Introductory drive (5 min) • 4 main drives (10 min/each) • 6 braking events per drive • Each scenario had an equal number of event severity Collision Warning Design

25. Results • Rank the warning modalities in order from 1 to 4 based on preference • Violation of assumption of a repeated measures ANOVA • Applied Friedman’s non-parametric analysis • Only when Friedman’s showed a significant difference between conditions was a post-hoc multiple comparison performed using Fisher’s least significant difference method Collision Warning Design

26. Collision Warning Design

27. Conclusions • Graded warning provided a greater safety margin • Graded warning induced fewer inappropriate responses to the nuisance alarms • Graded warning was more trusted • Warning modality had little effect on performance in severe braking events • Haptic warnings were preferred on several dimensions to auditory Collision Warning Design

28. Questions • In table 2, graded haptic beats single-stage haptic in everything except overall preference, what can account for this? • Does the data on table 2 match what you would have expected? • Graded is preferred for a one hour experiment, how about 5-10 years on daily basis? Collision Warning Design

29. Questions • Haptic is preferred over auditory in this study, is this a property of auditory or a property of the time span of the test, or some other factor? • Why express haptic through a seat and not a gas pedal as in previous studies? Collision Warning Design