david strayer department of psychology
DESCRIPTION
Multi-tasking on the Information Super Highway: Why Using a Cell Phone Can Make You Drive Like You’re Drunk. David Strayer Department of Psychology. RMPA: April 13, 2007. Research Questions. Does conversing on a cell phone interfere with driving? What are the sources of the interference? - PowerPoint PPT PresentationTRANSCRIPT
Multi-tasking on the Information Super Highway: Why Using a Cell Phone Can Make You Drive
Like You’re Drunk
David StrayerDepartment of Psychology
RMPA: April 13, 2007
Research Questions
Does conversing on a cell phone interfere with driving?
What are the sources of the interference? Peripheral interference (dialing, holding the phone) Attentional interference (cell phone conversation)
How significant is the interference?
Observational Study(Residential 4-way Intersections)
Odds ratio for failing to stop: 0.27 for drivers not using a cell phone 2.93 for drivers using a cell phone
Traffic Violation
No Traffic Violation
On Cell 82 28 110
Not on Cell 352 1286 1838
434 1314 1748
Epidemiological Studies(Case Crossover Design)
Redelmeier & Tibshirani (1997) NEJM 699 driver involved in a non-injury automobile accident 4-fold increase in risk of accident when using cell phone
McEvoy et al., (2005) BMJ 456 drivers requiring hospital attendance after automobile accident 4-fold increased likelihood of crashing when using a cell phone
Driving Simulator Studies (Car Following Paradigm)
Drivers conversing on a cell phone were 5 times more likely to be involved in a traffic accident
Traffic Accident
No Accident
Single-Task 2 119 121
Dual-Task 10 111 121
12 230 242
High-Fidelity Driving Simulator
Simulator-Based Studies
Car-following paradigm Follow periodically braking pace car Required timely and appropriate reactions Hands-free cell phone (positioned in advance)
Conditions Single vs. dual-task Low vs. moderate density *
Measures Reaction time Following distance Rear-end collisions
Low
Mod.
Single Dual
Reaction Time
800
850
900
950
1000
1050
1100
1150
Rea
ctio
n T
ime
Low Density Moderate Density
Single
Dual
Following Distance
2021222324252627282930
Follow
ing
Dis
tance
(M
eter
s)
Low Density Moderate Density
Single
Dual
Rear-end Collisions
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
Rea
r-en
d C
ollisi
ons
Low Density Moderate Density
SingleDual
Summary (Experiment 1)
Cell-phone driver’s Slower reaction times Drivers compensate by increasing following distance Increase in rear-end accidents
Cell-phone interference Even when manual contributions are eliminated Naturalistic conversations
Why Do Cell Phones Cause Interference?
From earlier studies, no interference from: Radio broadcasts (audio input) Books on tape & recorded conversations (audio/verbal input) Simple shadowing (audio/verbal input, verbal output)
Implies active engagement in conversation necessary
Impairments from both hand-held and hands-free units Implies central / cognitive locus Inattention-blindness (James, Neisser, Simons)
Why Do Cell Phones Cause Interference?
From earlier studies, no interference from: Radio broadcasts (audio input) Books on tape & recorded conversations (audio/verbal input) Simple shadowing (audio/verbal input, verbal output)
Implies active engagement in conversation necessary
Impairments from both hand-held and hands-free units Implies central / cognitive locus Inattention-blindness (James, Neisser, Simons)
Why Do Cell Phones Cause Interference?
From earlier studies, no interference from: Radio broadcasts (audio input) Books on tape & recorded conversations (audio/verbal input) Simple shadowing (audio/verbal input, verbal output)
Implies active engagement in conversation necessary
Impairments from both hand-held and hands-free units Implies central / cognitive locus Inattention-blindness (James, Neisser, Simons)
Experiment 2: 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
Recognition Memory
0
1
2
3
4
5
6
7
No.
Cla
ssifi
ed a
s "O
ld"
Single-Task Dual-Task Control
Recognition Memory Given Fixation
0
0.1
0.2
0.3
0.4
0.5
0.6
Con
ditio
nal
Rec
ognitio
n
Pro
bab
ility
Single-Task Dual-Task
Experiment 2a: Summary
50% drop in recognition memory from single to dual-task, consistent with inattention blindness interpretation
What about items more relevant to safe driving?
Do drivers divert attention from processing items of low task relevance (e.g., billboards), but protect high task relevance items (e.g., pedestrians)?
Experiment 2b: Effects of Traffic Relevance
Phase I: Single & dual-task driving Interstate driving (with traffic) Hands-free cell phone, naturalistic conversations Unique items placed in single & dual-task scenarios
Phase II: Surprise 2AFC recognition memory test Single-task items (driving only) Dual-task items (driving & phone) Control items (not seen while driving)
Driving Safety Relevance Ratings
Objects
0 10 20 30 40 50 60
Ave
rage
Rel
evan
ce R
atin
g
0
1
2
3
4
5
6
7
8
9
2AFC Recognition Memory Given Fixation(Corrected for Guessing)
0
0.05
0.1
0.15
0.2
0.25
0.3
Con
ditio
nal
Rec
ognitio
n
Pro
bab
ility
Single-Task Dual-Task
Dual-task interference not modulated by driving safety relevance
Experiment 2: Summary
Cell phone conversations create inattention blindness for traffic related events/scenes
Cell phone drivers look but fail to see up to half of the information in the driving environment
No evidence that cell phone drivers protect more traffic relevant information
Experiment 3: 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
Traffic-related Brain Activity
Time (Msec)
-200 0 200 400 600 800 1000 1200
Am
plitu
de
V
Single TaskDual Task
5 V
_
+
Experiment 3: Summary
Brain waves suppressed by cell phone conversations
Cell phone conversations impair encoding of information necessary for the safe operation of a motor vehicle
Cell Phone vs. Passenger Conversations
Conditions Single task / dual task Conversing on cell phone Conversing with passenger
Design Task (2) x Condition (2)
Single task
Cell
Passenger
Lane Keeping Errors
0
0.2
0.4
0.6
0.8
1
1.2
RM
S E
rror
Cell Phone Passenger Single-Task
Successful Navigation
0
20
40
60
80
100
% C
orre
ct E
xit
Cell Phone Passenger Single-Task
Traffic References
0
1
2
3
4
Num
ber
of R
efer
ence
s
Cell Phone Passenger
Summary (Experiment 4)
Cell-phone conversations More navigation errors Fewer references to traffic
Passenger conversations Collaborative problem solving Shared situation awareness Passenger actively supports the driver
Experiment 5: How Significant is the Interference?
Cell-phone vs. drunk-driver Redelmeier and Tibshirani (1997) reported epidemiological evidence
suggesting that “the relative risk [of being in a traffic accident while using a cell-phone] is similar to the hazard associated with driving with a blood alcohol level at the legal limit” (p. 465).
Cell-phone Driver vs. Drunk Driver
Car-following paradigm Follow periodically braking pace car Required timely and appropriate reactions
Conditions Single-task driving Cell-phone driving * Intoxicated driving (BAC= 0.08 wt/vol)
* Hands-free = Hand-held
Reaction Time
700
750
800
850
900
950
1000
1050
Rea
ctio
n T
ime
Intoxicated Driving Cell-Phone Driving
Following Distance
25.00
25.50
26.00
26.50
27.00
27.50
28.00
28.50
29.00
Follow
ing
Dis
tance
(m
eter
s)
Intoxicated Driving Cell-Phone Driving
Rear-end Collisions
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
Rea
r-en
d C
ollisi
ons
Intoxicated Driving Cell-Phone Driving
Summary (Experiment 5)
Compared to drunk driver, cell-phone driver’s reactions Slower reaction times Longer to recover lost speed following braking Drivers compensate by increasing following distance Increase in rear-end accidents
When controlling for time on task and driving conditions, cell-phone drivers’ performance is worse than that of the drunk driver
You Cannot Practice Away The Interference Cooper & Strayer et al., (2007) HFES
Accident Frequency for City and Highway Driving
Day 1
Training
Day 4
Training
Day 4
Transfer
Single Task
16 6 10 32
Dual Task
25 12 26 63
41 18 36 95
Teen Drivers More at Risk Chisholm et al., (2006) HFES
Accident Percentage – pedestrian and pullout vehicle events
Single-Task Dual-Task
Novice(< 6 months)
3.3% 6.4% 4.85%
Experienced(10 years)
0.0% 2.5% 1.25%
1.65% 4.45%
Research Questions
Does conversing on a cell phone interfere with driving? Yes
What are the sources of the interference? Peripheral interference (dialing, text messaging) Attentional interference (inattention blindness)
How significant is the interference? Worse than listening to radio/books on tape Worse than in-vehicle conversations More impairing than driving while intoxicated at legal limit
