A MetaAnalysis of the Effects of Cell Phones on Driving Performance: Implications for

1
A Meta-Analysis of the Effects of Cell Phones on
Driving Performance Implications for Policy and
Legislation Jeff Caird, Ph.D.,
Professor Cognitive Ergonomics Research Laboratory
International Symposium on Distracted Driving
Arlington, Virginia October 14, 2008
2
Is Cell Phone Legislation Based on Empirical
Evidence?

• Forty-five countries have implemented bans on
  driving with cell phones (Sundeen, 2006),
• Including U.K., Germany, France, Japan, the
  Netherlands and Australia.
• In Canada, New Foundland and Labrador, Québec,
  Nova Scotia have introduced bans.
• In the U.S., New York, New Jersey, D.C., and
  California have bans and many other states are
  currently debating legislation.

3
Why Not Address More Categories of Driver
Distraction Then Just Cell Phones?
Stutts et al. (2001, 2005)
4
Does Using a Cell Phone Increase Crash Risk?

• Redelmeier Tibshirani (1997), NEJM
• Handheld 3.9 2.76.1
• Hands-free 5.9 2.924.0
• McEvoy et al. (2005), BMJ
• Handheld 4.9 1.615.5
• Hands-free 3.8 1.88.0

5
Meta-Analysis Methods

• Meta-analysis combines results across studies to
  yield an overall estimate of effect size and
  compares effects between studies to understand
  moderating factors.
• Examined 106 driver performance studies from 1969
  to 2007 for methodological and statistical fit
  with our primary research questions.
• A total of 33 performance studies yielded 94
  effect size estimates with a total sample size
  greater than 2000 participants.

Caird, Willness, Steele Scialfa (2008)
6
Primary Research Questions

• Does conversation on cell phones, whether
  hand-held or hands-free, influence driving
  performance?
• 2. Are some age groups more susceptible to
  negative influences of cell phone use on driving?
• Are there differences in findings among
  laboratory, driving simulator and on-road
  studies?
• Do drivers adapt their driving behaviour to
  compensate for the higher crash risk while using
  a cell phone?

7
Exclusion and Inclusion Issues

• Deficiencies of statistical reporting.
• Variance in methodological quality and rigor
  across studies.
• Reconciliation of publications in multiple
  sources.
• Fit with dependant variable categories of
  reaction time, lateral positioning, headway and
  speed.

8
How Does Cell Phone Use Affect Driving?

• Reaction time
• Speed
• Headway
• Lateral control (i.e., staying within a lane)

9
What is the Impact of Cell Phones on Driving
Performance?
10
Does Conversation Target or Type Moderate RT or
Speed?
RT
Speed
11
Which is Worse, Hands-Free or Hand Held?
Mythbusters (2006)
12
Does Cell Phone Use and Age Matter?
13
Does Talking to a Passenger Affect Driving
Performance?
14
How Do Different Cell Phone Tasks Affect Response
Time?

15
Does Research Setting Affect Results?
16
Meta-Analysis Conclusions

• Overall a mean increase of 0.25 s was found for
  all types of phone-related tasks.
• Handheld and hands-free phones produced the same
  RT decrements.
• Driver using either phone do not appreciably
  compensate by giving greater headway or reducing
  their speed.
• Observed performance decrements probably
  underestimate the true behavior of drivers with
  mobile phones in their own vehicles.

17
What Are the Critical Research Gaps?

• Most drivers use handheld phones (95). However,
  most empirical studies have addressed hands-free
  phone use (k 37 v. k 5).
• Other tasks such as texting, emailing, browsing,
  and so forth while driving have fewer research
  studies but potentially more adverse costs.
• Research on novice drivers, who may be restricted
  from using their cell phones during GDL by their
  parents or DOT, is limited.

18
How Does Using an iPOD or Texting Affect Driver
Performance?

• Reaction time
• Lane keeping
• Eyes off road time

Chisholm et al. (2008)
19
Does Using a Cell Phone Affect Novice Drivers
More Than Experienced Drivers?
Cell phones are detrimental to the driving
performance of all, not just novice, drivers.
Caird et al. (in review)
20
NTSB Five Fatality Crash Investigation
National Transportation Safety Board (2003)
21
What Countermeasures Are Available?

• Legislation and Enforcement
• Corporate/Private Sector Policies
• Education and Licensing Restrictions
• Cell Phone and Telematic Design
• Social Norms

Caird Dewar (2007)
22
Social Norms and Driving

• Intolerance for drinking and driving
• Intolerance for engaging in distractions (of
  any kind) while driving.

Evans (2004)
23
Is Using a Cell Phone Like Driving Drunk?
Caird, Lees Edwards (2004)
Mythbusters (2006)
24
Acknowledgments

• Chelsea Willness, Susan Chisholm, Elise Teteris,
  Lisa Fern, Andrew Mayer, Julie Lockhart, Monica
  Lees, Jason LaBerge, Geoff Ho, Chris Edwards
• Alison Smiley, Chip Scialfa, Piers Steel, Bob
  Dewar, Don Kline
• AUTO21, Network of Centres of Excellence (NCE)
• University of California, Berkeley/PATH
• Insurance Bureau of Canada
• CAA Foundation for Traffic Safety

25
(No Transcript)
26
Jeff Caird, Ph.D., jkcaird_at_ucalgary.ca
International Symposium on Distracted Driving
Arlington, Virginia October 14, 2008