DEVICE RELATED DISTRACTION 

MEASUREMENT:

Preliminary Findings 

and Research Challenges

Elizabeth Mazzae, Riley Garrott, 

and Frank Barickman

NHTSA Vehicle Research and Test Center

Thomas Ranney

Transportation Research Center Inc.

May 16, 2001 
Background

n Driver distraction is a known safety 

problem

Ž 20-30% of crashes involved distraction 

(NASS CDS 95-98)

n New communication and information 

technologies have potential safety and 

social benefits 

n However, new devices may worsen the 

distraction problem
Distraction Assessment 

Research Methods

Open Road

(Public Roads) (Public Roads)

Test Track

(Closed Course) (Closed Course)

Test Vehicle

(Fixed 

Instrumentation) (Fixed 

Instrumentation)

Portable

Subject’s

Personal

Vehicle

Subject’s

Personal

Vehicle

Level of Experimental Control

Naturalistic

Remote 

Observation

From IV

Remote 

From IV

Fixed

Route Fixed

Route

Drivers’

Choice Drivers’

Choice

Test Vehicle

Fixed 

Instrumentation Fixed 

Simulator

Behavior Performance
NHTSA Research Program

n On-road studies

n Test track studies

n NADS studies
Wireless Telephone 

Interface Study

n Instrumented vehicles driven by 

members of general public for 6 weeks

Ž 3 wireless phone interfaces

– Hand-held, hands-free, hands-free with voice dialing

Ž 2 weeks per phone interface

n Compare for different interface designs:

Ž Use patterns 

Ž Conditions under which drivers are willing to use 

wireless phones
Research Challenges –

Wireless Phone Study

n Management of large data sets

n Identify valid calls made while 

driving
Data Reduction Effort

Made by Driver, 45 43 18

Stationary Vehicle

Made by Driver, 1 35 3

Wrong Interface

% Usable Calls 70% 65% 77%

TOTAL 176 228 106

Other 4 0 1

Made by 3 2 2

Passenger

Made by Driver 123 148 82

While Driving

Totally HandsFree PhoneConventional 

Hands-Free Phone

Hand-Held 

Phone

Type of Call / 

Condition

Phone Call Breakdown (Phase One)
Preliminary 

Phone Call Data

Preliminary Number of Calls While Driving 

by Wireless Phone Interface

(Phase One, 5 subjects)

123

148

82

0

50

100

150

200

Hand-Held

Phone

Conventional

Hands-Free 

Totally HandsFree

Wireless Phone Interface

Number 

 of Calls
Preliminary 

Phone Call Data

Preliminary Call Durations While Driving

(Phase One, 5 subjects) 

(does not include dialing)

73 72

97

0

20

40

60

80

100

120

Hand-Held Phone Conventional

Hands-Free 

Totally Hands-Free

Wireless Phone Interface

Call Duration (seconds)
Research Challenges –

Wireless Phone Study

n Data loss due to field study issues

n Match exposure between conditions

n Recruitment issues, self-reporting
Preliminary 

Phone Call Data

Preliminary Number of Calls While Driving By Subject 

(Phase One)

27

41

25

10

19 20

59

14

0

56

10

30

6 3

33

0

10

20

30

40

50

60

70

Subject 1 Subject 2 Subject 3 Subject 4 Subject 5

Number of Calls

Hand-Held Phone

Conventional Hands Free 

Totally Hands-Free
Lessons Learned –

Wireless Phone Study

n Selective recruitment for naturalistic 

studies

n Use of event markers in data
Test Track Studies

n Evaluation of voice interface for invehicle devices

n Demonstration study of everyday 

distractions
Effects of Voice Technology 

on Test Track Driving 

Performance

n Cooperative study between NHTSA 

and Transport Canada

ß Compare voice and non-voice 

technologies for:

Ž Phone dialing

Ž Radio tuning

Ž E-mail retrieval
Effects of Voice Technology 

on Test Track Driving 

Performance

n Driving performance and eye glance 

behavior will be analyzed

n Results will help determine what 

tasks are appropriate for drivers to 

access while driving on public roads
Research Challenges –

Voice Interface Test Track 

Study

n Conducting research in experimental 

settings removes drivers’ motives and 

reasons for engaging in distracting 

behaviors

n Cannot recreate the visual and 

operational richness of on-road 

conditions

n Research limited to distraction 

potential
Demonstration Study of 

Everyday Distractions

n Closed-course study to assess effects of 

various secondary tasks on driving 

performance

n Subjects drove repeated laps over 

winding road course

n Unexpected events combined with 

everyday in-vehicle distractions

n Separate scores for primary (driving) and 

secondary (distracting) tasks
Results Based on Test 

Scores

n Based on examination of 12 

subjects:

Ž On average, performing a secondary task 

was associated with a 15% reduction in 

driving performance, relative to the 

average baseline score

Ž On 88% of all driving laps, the secondary 

task impaired driving performance. 
Cost of Performing 

Secondary Tasks while 

Driving

Mean for all secondary tasks 15

CD Changing 17

Destination Entry 18

Grooming/Eating 12

Phone Dialing 8

List Writing 25

Reading 16

Counting 12

Average Performance 

Decrement (%)

Task
Research Challenges –

Demonstration Study of 

Everyday Distractions

n Development of closed course 

distraction assessment test 

concept

n Development of unexpected 

events

n Timing of unexpected events
Demonstration Study of 

Everyday Distractions
Demonstration Study of 

Everyday Distractions
Demonstration Study of 

Everyday Distractions
Research Challenges –

Demonstration Study of 

Everyday Distractions

n Creation of incentives for 

secondary task performance

n Development of metrics for 

assessing performance
Lessons Learned –

Test Track Distraction Studies

n Scoring and competitiveness can 

be used to create incentive for task 

performance

n Typical roadway traffic control 

devices can be used to create a 

more realistic visual environment
NADS Research

n National Advanced Driving Simulator 

(NADS)
NADS Studies

n Driver workload and distraction

Ž Due to Wireless Communications Devices

Ž Due to In-Vehicle Information Systems
Research Challenges –

NADS Distraction Studies

n Acclimation to simulator and devices 

while driving is limited due to cost

n Creation of incentives for secondary 

task performance

n How to create compelling conversation

n NADS validation
Overall Research 

Challenges

n Selecting appropriate research tool

Ž Experimental methods trade realism for control

Ž Naturalistic methods can lack control necessary 

to provide definitive answers to questions

n Relating findings to potential safety 

impact
Conclusions

n Understanding distraction requires a 

coordinated research program:

Ž Naturalistic studies to evaluate drivers’ willingness 

to engage in distracting activities under normal 

driving conditions and resulting errors

Ž On-road experiments to understand distraction 

potential in routine situations

Ž Closed-course experiments to understand 

distraction potential in routine and near-critical 

situations

Ž Simulator studies to understand distraction effects in 

near-critical and critical situations
Conclusions

n Research program will attempt to:

Ž Determine safety implications of device use 

under various conditions 

Ž Develop guidelines for their performance 

features and appropriate use in vehicles

Ž Investigate integrating collision avoidance 

systems with information and 

communication technologies to mitigate 

their distracting effects

Ž Quantify benefits and risks