Background and aims
Cannabis and alcohol are frequently detected in fatal and injury motor vehicle crashes. While epidemiological meta‐analyses of cannabis and alcohol have found associations with an ...increase in crash risk, convergent evidence from driving performance measures is insufficiently quantitatively characterized. Our objectives were to quantify the magnitude of the effect of cannabis and alcohol—alone and in combination—on driving performance and behaviour.
Methods
Systematic review and meta‐analysis. We systematically searched Academic Search Complete, CINAHL, Embase, Scopus, Google Scholar, MEDLINE, PsycINFO, SPORTDiscus and TRID. Of the 616 studies that underwent full‐text review, this meta‐analysis represents 57 studies and 1725 participants. We extracted data for hazard response time, lateral position variability, lane deviations or excursions, time out of lane, driving speed, driving speed variability, speed violations, time speeding, headway, headway variability and crashes from experimental driving studies (i.e. driving simulator, closed‐course, on‐road) involving cannabis and/or alcohol administration. We reported meta‐analyses of effect sizes using Hedges’ g and r.
Results
Cannabis alone was associated with impaired lateral control e.g. g = 0.331, 95% confidence interval (CI) = 0.212–0.451 for lateral position variability; g = 0.198, 95% CI = 0.001–0.395 for lane excursions) and decreased driving speed (g = –0.176, 95% CI = –0.298 to –0.053. The combination of cannabis and alcohol was associated with greater driving performance decrements than either drug in isolation e.g. g = 0.480, 95% CI = 0.096–0.865 for lateral position variability (combination versus alcohol); g = 0.525, 95% CI = 0.049–1.002 for time out of lane (versus alcohol); g = 0.336, 95% CI = 0.036–0.636 for lateral position variability (combination versus cannabis; g = 0.475, 95% CI = 0.002–0.949 for time out of lane (combination versus cannabis). Subgroup analyses indicated that the effects of cannabis on driving performance measures were similar to low blood alcohol concentrations. A scarcity of data and study heterogeneity limited the interpretation of some measures.
Conclusions
This meta‐analysis indicates that cannabis, like alcohol, impairs driving, and the combination of the two drugs is more detrimental to driving performance than either in isolation.
The empirical basis for legislation to limit cell phones while driving is addressed. A comprehensive meta-analysis of the effects of cell phones on driving performance was performed. A total of 33 ...studies collected through 2007 that met inclusion criteria yielded 94 effect size estimates, with a total sample size of approximately 2000 participants. The dependent variables of reaction time, lateral vehicle control, headway and speed and the moderating variables of research setting (i.e., laboratory, simulator, on-road), conversation target (passenger, cell phone) and conversation type (cognitive task, naturalistic) were coded. Reaction time (RT) to events and stimuli while talking produced the largest performance decrements. Handheld and hands-free phones produced similar RT decrements. Overall, a mean increase in RT of .25
s was found to all types of phone-related tasks. Observed performance decrements probably underestimate the true behavior of drivers with mobile phones in their own vehicles. In addition, drivers using either phone type do not appreciably compensate by giving greater headway or reducing speed. Tests for moderator effects on RT and speed found no statistically significant effect size differences across laboratory, driving simulation and on-road research settings. The implications of the results for legislation and future research are considered.
•Twenty-eight experimental studies of texting and driving were identified and meta-analysed.•Typing and reading text messages adversely affected nearly all measures of safe driving.•Texting while ...driving produces visual, cognitive and physical driver distraction.•A variety of countermeasures will be required to prevent texting and driving injuries and fatalities.
Text messaging while driving is considered dangerous and known to produce injuries and fatalities. However, the effects of text messaging on driving performance have not been synthesized or summarily estimated. All available experimental studies that measured the effects of text messaging on driving were identified through database searches using variants of “driving” and “texting” without restriction on year of publication through March 2014. Of the 1476 abstracts reviewed, 82 met general inclusion criteria. Of these, 28 studies were found to sufficiently compare reading or typing text messages while driving with a control or baseline condition. Independent variables (text-messaging tasks) were coded as typing, reading, or a combination of both. Dependent variables included eye movements, stimulus detection, reaction time, collisions, lane positioning, speed and headway. Statistics were extracted from studies to compute effect sizes (rc). A total sample of 977 participants from 28 experimental studies yielded 234 effect size estimates of the relationships among independent and dependent variables. Typing and reading text messages while driving adversely affected eye movements, stimulus detection, reaction time, collisions, lane positioning, speed and headway. Typing text messages alone produced similar decrements as typing and reading, whereas reading alone had smaller decrements over fewer dependent variables. Typing and reading text messages affects drivers’ capability to adequately direct attention to the roadway, respond to important traffic events, control a vehicle within a lane and maintain speed and headway. This meta-analysis provides convergent evidence that texting compromises the safety of the driver, passengers and other road users. Combined efforts, including legislation, enforcement, blocking technologies, parent modeling, social media, social norms and education, will be required to prevent continued deaths and injuries from texting and driving.
•SCE risk is greatest for tasks that require drivers to look away from the roadway.•More research needed to validate SCEs against real-world crash risk.•Limitations and potential biases within NDS ...designs are identified and addressed.
A systematic review and meta-analysis of naturalistic driving studies involving estimates of safety-critical event risk associated with handheld device use while driving is described. Fifty-seven studies identified from targeted databases, journals and websites were reviewed in depth, and six were ultimately included. These six studies, published between 2006 and 2014, encompass seven sets of naturalistic driver data and describe original research that utilized naturalistic methods to assess the effects of distracting behaviors. Four studies involved non-commercial drivers of light vehicles and two studies involved commercial drivers of trucks and buses. Odds ratios quantifying safety-critical event (SCE) risk associated with talking, dialing, locating or answering, and texting or browsing were extracted. Stratified meta-analysis of pooled odds ratios was used to estimate SCE risk by distraction type; meta-regression was used to test for sources of heterogeneity. The results indicate that tasks that require drivers to take their eyes off the road, such as dialing, locating a phone and texting, increase SCE risk to a greater extent than tasks that do not require eyes off the road such as talking. Although talking on a handheld device did not increase SCE risk, further research is required to determine whether it indirectly influences SCE risk (e.g., by encouraging other cell phone activities). In addition, a number of study biases and quality issues of naturalistic driving studies are discussed.
Objective
An up-to-date meta-analysis of experimental research on talking and driving is needed to provide a comprehensive, empirical, and credible basis for policy, legislation, countermeasures, and ...future research.
Background
The effects of cell, mobile, and smart phone use on driving safety continues to be a contentious societal issue.
Method
All available studies that measured the effects of cell phone use on driving were identified through a variety of search methods and databases. A total of 93 studies containing 106 experiments met the inclusion criteria. Coded independent variables included conversation target (handheld, hands-free, and passenger), setting (laboratory, simulation, or on road), and conversation type (natural, cognitive task, and dialing). Coded dependent variables included reaction time, stimulus detection, lane positioning, speed, headway, eye movements, and collisions.
Results
The overall sample had 4,382 participants, with driver ages ranging from 14 to 84 years (M = 25.5, SD = 5.2). Conversation on a handheld or hands-free phone resulted in performance costs when compared with baseline driving for reaction time, stimulus detection, and collisions. Passenger conversation had a similar pattern of effect sizes. Dialing while driving had large performance costs for many variables.
Conclusion
This meta-analysis found that cell phone and passenger conversation produced moderate performance costs. Drivers minimally compensated while conversing on a cell phone by increasing headway or reducing speed. A number of additional meta-analytic questions are discussed.
Application
The results can be used to guide legislation, policy, countermeasures, and future research.
•Meta-analysis of voice-recognition system interaction on driving performance.•Voice-recognition system interaction while driving has a distraction cost.•Some improved performance relative to ...visual-manual systems.
Driver distraction is a growing and pervasive issue that requires multiple solutions. Voice-recognition (V-R) systems may decrease the visual-manual (V-M) demands of a wide range of in-vehicle system and smartphone interactions. However, the degree that V-R systems integrated into vehicles or available in mobile phone applications affect driver distraction is incompletely understood. A comprehensive meta-analysis of experimental studies was conducted to address this knowledge gap. To meet study inclusion criteria, drivers had to interact with a V-R system while driving and doing everyday V-R tasks such as dialing, initiating a call, texting, emailing, destination entry or music selection. Coded dependent variables included detection, reaction time, lateral position, speed and headway. Comparisons of V-R systems with baseline driving and/or a V-M condition were also coded. Of 817 identified citations, 43 studies involving 2000 drivers and 183 effect sizes (r) were analyzed in the meta-analysis. Compared to baseline, driving while interacting with a V-R system is associated with increases in reaction time and lane positioning, and decreases in detection. When V-M systems were compared to V-R systems, drivers had slightly better performance with the latter system on reaction time, lane positioning and headway. Although V-R systems have some driving performance advantages over V-M systems, they have a distraction cost relative to driving without any system at all. The pattern of results indicates that V-R systems impose moderate distraction costs on driving. In addition, drivers minimally engage in compensatory performance adjustments such as reducing speed and increasing headway while using V-R systems. Implications of the results for theory, design guidelines and future research are discussed.
Pedestrians are commonly involved in vehicle collisions that result in injuries and fatalities. Pedestrian distraction has become an emerging safety issue as more pedestrians use their mobile phones ...while walking and crossing the street.
The purpose of this research synthesis and meta-analysis is to determine the extent to which cell phone conversation, text messaging or browsing, and listening to music affect a number of common pedestrian behavioural measures.
A keyword search was developed with a subject librarian that used MeSH terms from selected databases including PsycINFO, SPORTDiscus, Medline and TRID. Supplemental searches were also conducted with Google Scholar and Mendeley.
Thirty-three studies met inclusion criteria and were subjected to data extraction. Statistical information (ie,
) was extracted to generate standardised mean difference effect sizes (ie, Cohen's d) and
effect sizes.
Fourteen experimental studies were ultimately included in an N-weighted meta-analysis (
=81 effect sizes), and eight observational studies were included in a qualitative overview. Both mobile phone conversation and text messaging increased rates of hits and close calls. Texting decreased rates of looking left and right prior to and/or during street crossing. As might be expected, text messaging was generally found to have the most detrimental effect on multiple behavioural measures.
A variety of study quality issues limit the interpretation and generalisation of the results, which are described, as are future study measurement and methods improvements.
•Insufficient nighttime conspicuity contributes to pedestrian injuries and fatalities.•Body orientation and speed of motion affects judgments of biomo pedestrians.•Running and walking pedestrians ...chosen as more recognizable than standing.•Body orientation effects depend on pedestrian speed of motion.
Insufficient conspicuity of pedestrians at night is a fundamental contributor to injuries and fatalities. Retro-reflective clothing that enhances biological motion perception increases detection and identification of pedestrians at night.
To determine how speed of motion and body orientation affect observers’ judgments about the recognisability of pedestrians with bio-motion retro-reflectors.
The stimuli used in this study were videos of a retro-reflectively outfitted pedestrian on a treadmill filmed in a nighttime road environment. Forty undergraduate students observed videos of pedestrians who were standing, walking or running with the side or back of their body oriented towards the observer. Participants decided which of the two pedestrians was most recognizable as a person. Judgments were made in high beams and low beams at 80 m, 160 m and 240 m.
For both orientations, observers judged that walking and running pedestrians were more recognizable than standing pedestrians. Observers also judged that running pedestrians were more recognizable than walkers. The effect of pedestrian orientation was dependent on speed. When standing, pedestrians in the back orientation were selected more often, but when running, side-oriented pedestrians were selected as the most recognizable.
Speed of motion and body orientation affect observers’ judgments of the recognisability of pedestrians wearing retro-reflectors at night. Observers choose moving pedestrians (i.e., those who are walking or running) in biomo retro-reflectors as more recognizable as people than pedestrians who stand. The results fill several gaps in the literature and have practical and future research implications, which are discussed.
This study examined situations where drivers looked-but-failed-to-see (LBFTS) hazards, and whether passenger conversation and gender affected hazard detection rates. To reliably produce LBFTS errors, ...40 young drivers (
M
=
20.3) encountered motorcycles and pedestrians while making left turns in the University of Calgary Driving Simulator (UCDS). Prior to turn initiation the UCDS screens flickered using an extension of change blindness methods. In addition, drivers either drove alone or conversed with an attractive confederate passenger. Measures of LBFTS errors, hazard detection and social factors were analyzed. Higher rates of LBFTS errors and hazard detection occurred while conversing than while driving alone. A discriminant function analysis (DFA) using conversation and gender as predictors accurately classified LBFTS errors. Higher passenger attraction and higher extroversion were related to critical events being missed. The basis of LBFTS errors in divided and selective attention and classification implications are discussed.
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