Measuring Cognitive
Distraction in the
Vehicle
David Strayer
University of Utah
Multitasking and Driver Distraction
“Any man who can drive safely while kissing a
pretty girl is simply not giving the kiss the
attention it deserves.”
-- Albert Einstein
FACT: People cannot successfully perform two
attention-demanding tasks simultaneously without
declines in performance on one or both tasks
The Driver Distraction Triad
Visual
Eyes off the Road
High
Moderate
Low
Manual
Hands off the Wheel
Cognitive
Mind off the Drive
An Example of Cognitive Distraction
Observational Study
(Intersection Study – 56K Drivers)



Cell Phone
No Phone
Failed to Stop
2416
12567
14983
Stopped
Appropriately
3332
38294
41626
5748
50861
56609
Traffic Violations 26.5%
Cell Phone Usage 10.2%
OR: 2.21 (95% CI 2.09 to 2.33)
Basketball Counting Task
Report the pass count for team in white
Inattention-Blindness
•
Test for evidence of cell-phone
induced inattention blindness
•
•
High-fidelity driving simulator
Hands-free cell phone
Naturalistic conversation with confederate
Eye tracker
•
Two phases to the study:
•
•
• Phase 1: Single & dual-task driving
• Phase 2: Recognition memory tests for
objects encountered while driving
Conditional
Recognition Probability
Recognition Memory Given Fixation
0.6
0.5
0.4
0.3
0.2
0.1
0
Single-Task
Dual-Task
Encoding or Retrieval Deficits?
•
Encoding deficits
• Reduced attention to perceptual inputs
• Clear implications for traffic safety
•
Retrieval deficits
• Failure to retrieve prior episodes
• Less clear implications for traffic safety
•
Event-related brain potentials recorded to traffic brake lights
• Single-task
• Dual-task
Amplitude V
Traffic-related Brain Activity
Elicited by Brake Lights
Single Task
Dual Task
Brake
-200
0
200
400
600
Time (Msec)
800
1000
1200
Cognitive Distraction: Inattention Blindness
Successful Navigation to Rest Stop
% Correct Exit
100
80
60
40
20
0
Cell Phone
Passenger
Single-Task
Cell-Phone Conversation
Passenger Conversation
Are We Reaching a Tipping Point?
Benchmarking Cognitive Distraction
►
How do we quantify
cognitive sources of
distraction?
►
How can we use this
information to inform
public policy?
Benchmarking Cognitive Distraction
•
Sources of Driver Distraction
•
•
•
•
•
•
•
•
•
•
Baseline driving ★
Radio
Book on tape
Passenger conversation
Hand-held phone conversation
Hands-free conversation
Voice messaging / e-mail (speech to text & text to speech)
OSPAN task (memory/math task) ★★★★★
Driving Simulator
On-Road Vehicle
A New Metric for Cognitive Distraction
•
Driving Simulator Measures
•
•
•
•
•
Brake RT
Following Distance
Brain Measures (ERPs to brake lights)
NASA TLX (mental workload)
Detection-Response Task (new ISO standard)
• RT to green light (20/80)
• Miss rate
• ERPs to green light
•
On-Road Vehicle
• NASA TLX (mental workload)
• Brain Measures (ERPs to brake lights)
• Detection-Response Task (new ISO standard)
• RT to green light (20/80)
• Miss rate
• ERPs to green light
The Detection-Reaction Time (DRT) task
• The DRT Task
• New ISO Standard
• 20% Green Targets
• 80% Red Distractors
•
RT to Targets
•
Missed Targets
•
ERPs to Targets
Target Light
Microswitch
A New Metric for Cognitive Distraction
(DRT Reaction Time)
DRT Reaction Time (Phase 2)
660
640
620
600
580
560
540
520
500
Single
Radio
Audiobook Passenger Handheld Handsfree Textspeech
Ospan
A New Metric for Cognitive Distraction
(DRT Accuracy)
DRT Accuracy Rate (Phase 2)
1
0.99
0.98
0.97
0.96
0.95
0.94
0.93
0.92
0.91
0.9
Single
Radio
Audiobook Passenger
Handheld
Handsfree Textspeech
Ospan
A 5-Star Rating System
for Cognitive Distraction
Summary and Conclusions
•
Three sources of Driver Distraction
• Visual
• Manual
• Cognitive
•
Cognitive Distraction
• Inattention blindness
• Impaired recognition memory, suppressed ERPs
• Impaired visual scanning (tunnel vision)
Applied Cognition Laboratory