The Logic for the Distracted Driver

David Strayer

Perspectives on Driving Simulation

Behavioral equation Study design Scenario development Behavioral measures Statistical analyses

Driver Distraction

An activity that competes or interferes with processing information critical to the safe operation of a motor vehicle (i.e., some aspect of driving performance is impaired by the concurrent performance of this activity).

Distracted by something Not all sources of distraction are equal

Sensory/motor (e.g., lighting a cigarette, looking at a map) Attentional/cognitive (e.g., talking on a cell phone)

What is the duration of the activity?

I-SIM Driving Simulator

Customized Data Collection Software

5 networked microprocessors Multicast data sampled 60 Hz Real-time stream

Driving parameters (speed, lane position, etc.) Parameters of all other objects in scenario Trigger real-time “outside” events (e.g., ERP recording)

Off-line analyses extract meaningful data C++ code freely available

Study Design

Car-following paradigm Follow periodically braking pace car (32 trials) Required timely and appropriate reactions Single- and Dual-task conditions (counterbalanced) Dual-task: Hands-free cell phone (positioned in advance) Naturalistic conversations with friends

Performance Measures Driving speed Reaction time Recovery time Following distance Lane keeping Time to collision

Car Following Details

24 mile multi-lane beltway (straight + gradual turns)

Daytime, dry pavement

Pace car programmed to travel in right lane and brake at 32 randomly distributed locations (unpredictable)

Distractor vehicles programmed to travel in left lane between 5 and 10% faster than pace car, providing impression of steady flow of traffic (manipulation of perceptual load)

Scenario duration ~ 10 minutes

Car Following Paradigm

Time (Secs)

20

40

60

80

100

Pace Car's Speed (MPH)

Driver's Speed (MPH)

Following Distance (Meters)

Pace Car's Brake Lights

Driver's BrakeResponse

Building Driving Profiles

Time (Secs)

20

40

60

80

100

Pace Car's Speed (MPH)

Driver's Speed (MPH)

Following Distance (Meters)

Pace Car's Brake Lights

Driver's BrakeResponse

Time (~ 10 minutes)

0 2000 4000 6000 8000 10000 12000 14000 16000 18000

Speed (MPH)

0

20

40

60

80

Driving Profile Data Matrix(Method borrowed from ERP literature)

1 2 3 4 5 6 .. .. .. .. .. .. .. .. 3002

3

4

..

..

..

..

..

32

Time

Tri

als

Average across trials to create a driving profile for each subject/condition(Noise decreases as a function of the sqrt of N)

Driving Speed Profile

Time (sec)

0 1 2 3 4 5 6 7 8 9 10

Speed (MPH)

50

52

54

56

58

60

Single-TaskDual-Task

Reaction Time

Reaction Time (msec)

500

600

700

800

900

1000

1100

Single-TaskDual-Task

½ Recovery Time

1/2 Recovery Time (secs)

3

4

5

6

7

Single-TaskDual-Task

Following Distance Profile

Time (sec)

0 1 2 3 4 5 6 7 8 9 10

Distance (meters)

18

20

22

24

26

28

Single-TaskDual-Task

Effects of Cell Phone Conversations on Driving (Meta-analysis using car following paradigm)

Drivers conversing on a cell phone were 5 times more likely to be involved in a traffic accident χ2(1)=6.1, p=0.013

Traffic Accident

No Accident

Single-Task 2 118 120

Dual-Task 10 110 120

12 228 240

Discriminating Distractions

Not all sources of distraction are equal Multivariate Analysis of Variance Discriminant function analysis

Latest Developments

ASL 501 mobile eye-tracker Eye-scanning patterns

Fix probability Fix duration

Conditional recognition memory analyses Video tape sessions

Detailed coding of behavior Audio tape sessions

Conversation analysis Turn taking Content analysis