Association between cellular-telephone calls and motor vehicle collisions

Self-reported and observed risky driving behaviors among frequent and infrequent cell phone users

The apparently higher crash risk among individuals who use cell phones while driving may be due both to the direct interference of cell phone use with the driving task and tendencies to engage in risky driving behaviors independent of cell phone use. Measurements of actual highway driving performance, self-reported aberrant driving behaviors as measured by the Manchester Driver Behavior Questionnaire (DBQ), and attitudes toward speeding, passing behaviors and relative concern about being involved in a crash were assessed. Individuals who reported frequently using cell phones while driving were found to drive faster, change lanes more frequently, spend more time in the left lane, and engage in more instances of hard braking and high acceleration events. They also scored higher in self-reported driving violations on the DBQ and reported more positive attitudes toward speeding and passing than drivers who did not report using a cell phone regularly while driving. These results indicate that a greater reported frequency of cell phone use while driving is associated with a broader pattern of behaviors that are likely to increase the overall risk of crash involvement.

Fatalities of pedestrians, bicycle riders, and motorists due to distracted driving motor vehicle crashes in the U.S., 2005-2010

OBJECTIVE

Distracted driving is an increasingly deadly threat to road safety. This study documents trends in and characteristics of pedestrian, bicycle rider, and other victim deaths caused by distracted drivers on U.S. public roads.

METHODS

We obtained data from the Fatality Analysis Reporting System database from 2005 to 2010 on every crash that resulted in at least one fatality within 30 days occurring on public roads in the U.S. Following the definition used by the National Highway Traffic Safety Administration, we identified distracted driving based on whether police investigators determined that a driver had been using a technological device, including a cell phone, onboard navigation system, computer, fax machine, two-way radio, or head-up display, or had been engaged in inattentive or careless activities.

RESULTS

The rate of fatalities per 10 billion vehicle miles traveled increased from 116.1 in 2005 to 168.6 in 2010 for pedestrians and from 18.7 in 2005 to 24.6 in 2010 for bicyclists. Pedestrian victims of distracted driving crashes were disproportionately male, 25-64 years of age, and non-Hispanic white. They were also more likely to die at nighttime, be struck by a distracted driver outside of a marked crosswalk, and be in a metro location. Bicycling victims of distracted crashes were disproportionately male, non-Hispanic white, and struck by a distracted driver outside of a crosswalk. Compared with pedestrians, bicyclists were less likely to be hit in early morning.

CONCLUSIONS

Distracted drivers are the cause of an increasing share of fatalities found among pedestrians and bicycle riders. Policies are needed to protect pedestrians and bicycle riders as they cross intersections or travel on roadways.

Concurrent processing of vehicle lane keeping and speech comprehension tasks

With the growing prevalence of using in-vehicle devices and mobile devices while driving, a major concern is their impact on driving performance and safety. However, the effects of cognitive load such as conversation on driving performance are still controversial and not well understood. In this study, an experiment was conducted to investigate the concurrent performance of vehicle lane keeping and speech comprehension tasks with improved experimental control of the confounding factors identified in previous studies. The results showed that the standard deviation of lane position (SDLP) was increased when the driving speed was faster (0.30 m at 36 km/h; 0.36 m at 72 km/h). The concurrent comprehension task had no significant effect on SDLP (0.34 m on average) or the standard deviation of steering wheel angle (SDSWA; 5.20° on average). The correct rate of the comprehension task was reduced in the dual-task condition (from 93.4% to 91.3%) compared with the comprehension single-task condition. Mental workload was significantly higher in the dual-task condition compared with the single-task conditions. Implications for driving safety were discussed.

Gender Factor in Lane Keeping and Speech Comprehension Dual Tasks

Driving-related dual-task performance has been studied by many transportation human factors studies; however, previous studies on the effects of cognitive load on driving performance have obtained mixed results. In the current study, we focus on the analysis of the effect of gender factor on lane keeping and speech comprehension dual-task performance with improved experimental control of potential confounding factors. The results showed that the speech comprehension task did not significantly affect lane keeping performance when priority was given to lane keeping, at least within the approximate 80 min of the experiment. The speech comprehension performance in dual-task showed a speed-accuracy tradeoff that sacrificed accuracy for speed. Males showed better lane keeping ability in single-task, because the increase of standard deviation of lane position ( SDLP) with higher driving speed was less dramatic in males than females. Females showed better speech comprehension ability indicated by higher comprehension correct rate. The interaction between the gender and dual-task factors was only significant in a three-way interaction involving vehicle speed. It shows that females, in comparison to males, had a trend of dual-task lane keeping improvement with increasing speed. Implications from the results are discussed.

Vehicle-based studies of driving in the real world: the hard truth?

Real-world studies of driving behaviour and safety have face validity and have the distinct advantage of focussing on driving in its natural habitat. But their very naturalism can lead to problems with confounds and with noise in the data. This paper reviews the three major categories of on-road studies - controlled observation, field operational tests and naturalistic driving studies - and discusses the major applications of each study type. It also assesses some of the methodological issues that arise in one or more category of study.

Driving with pets as a risk factor for motor vehicle collisions among older drivers

Increasing rates of distraction-related motor vehicle collisions (MVCs) continue to raise concerns regarding driving safety. This study sought to evaluate a novel driving-related distraction, driving with a pet, as a risk factor for MVCs among older, community dwelling adults. Two thousand licensed drivers aged 70 and older were identified, of whom 691 reported pet ownership. Comparing pet owners who did and did not drive with their pets, neither overall MVC rates (rate ratio [RR] 0.97, 95% confidence interval [CI] 0.75-1.26) nor at-fault MVC rates (RR 0.84, 95% CI 0.57-1.24) were elevated. However, those who reported always driving with a pet in the vehicle had an elevated MVC rate (RR 1.89, 95% CI 1.10-3.25), as compared to those who did not drive with a pet. The MVC rate was not increased for those reporting only sometimes or rarely driving with a pet in the vehicle. The current study demonstrates an increased risk of MVC involvement in those older drivers who always take a pet with them when they drive a vehicle. When confronted with an increased cognitive or physical workload while driving, elderly drivers in prior studies have exhibited slower cognitive performance and delayed response times in comparison to younger age groups. Further study of pet-related distracted driving behaviors among older drivers as well as younger populations with respect to driver safety and performance is warranted to appropriately inform the need for policy regulation on this issue.

A simulator evaluation of the effects of attention maintenance training on glance distributions of younger novice drivers inside and outside the vehicle

Driver distraction inside and outside the vehicle is increasingly a problem, especially for younger drivers. In many cases the distraction is associated with long glances away from the forward roadway. Such glances have been shown to be highly predictive of crashes. Ideally, one would like to develop and evaluate a training program which reduced these long glances. Thus, an experiment was conducted in a driving simulator to test the efficacy of a training program, FOCAL, that was developed to teach novice drivers to limit the duration of glances that are inside the vehicle while performing an in-vehicle task, such as looking for a CD or finding the 4-way flashers. The test in the simulator showed that the FOCAL trained group performed significantly better than the placebo trained group on several measures, notably on the percentage of within-vehicle glances that were greater than 2, 2.5, and 3 s. However, the training did not generalize to glances away from the roadway (e.g., when drivers were asked to attend to a sign adjacent to the roadway, both trained and untrained novice drivers were equally likely to make especially long glances at the sign).

Bicycling safety and distracted behavior in The Hague, the Netherlands

As planners and public health officials in many cities around the world seek to increase bicycle ridership, bicyclists who are performing a secondary task (such as listening to a portable music device) may pose a risk to public safety. This study examines bicycling safety and potentially distracted behavior in The Hague, the Netherlands, a place where bicycling is a common, everyday travel mode among all walks of life and where bicycling infrastructure is well developed. Based on 1360 observations of bicycling behavior, this study shows that bicyclists who were using a cell phone, listening to a portable music device, or talking with other bicyclists exhibited more unsafe behaviors than those bicyclists who were not performing a secondary task. Furthermore, bicyclists who were performing a secondary task also more frequently created situations where other people had to evade them to avoid an accident. As with distracted car driving, the performance of a secondary task while bicycling may be unsafe for the person engaging in the behavior as well as for other people around them.

To call or not to call--that is the question (while driving)

We studied whether decisions to engage in cell phone conversation while driving and the consequences of such decisions are related to the driver's age, to the road conditions (demands of the driving task), and to the driver's role in initiating the phone call (i.e. the driver as caller vs. as receiver). Two experiments were performed in a driving simulator in which driver age, road conditions and phone conversation, as a secondary task, were manipulated. Engagement in cell phone conversations, performance in the driving and the conversation tasks, and subjective effort assessment were recorded. In general, drivers were more willing to accept incoming calls than to initiate calls. In addition, older and younger drivers were more susceptible to the deleterious effects of phone conversations while driving than middle aged/experienced drivers. While older drivers were aware of this susceptibility by showing sensitivity to road conditions before deciding whether to engage in a call or not, young drivers showed no such sensitivity. The results can guide the development of young driver training programs and point at the need to develop context-aware management systems of in-vehicle cell phone conversations.

Evidence-based practice in primary prevention of spinal cord injury

A spinal cord injury (SCI) not only causes paralysis, but also has long-term impact on physical and mental health. There are between 236,000 to 327,000 individuals living with the consequences of SCI in the United States, and the economic burden on the individuals sustaining the injury, their support network, and society as a whole is significant. The consequences of SCI require that health care professionals begin thinking about primary prevention. Efforts are often focused on care and cure, but evidence-based prevention should have a greater role. Primary prevention efforts can offer significant cost benefits, and efforts to change behavior and improve safety can and should be emphasized. Primary prevention can be applied to various etiologies of injury, including motor vehicle crashes, sports injuries, and firearm misuse, with a clear goal of eliminating unnecessary injury and its life-changing impact.

The effects of cell phone conversations on the attention and memory of bystanders

The pervasive use of cell phones impacts many people–both cell phone users and bystanders exposed to conversations. This study examined the effects of overhearing a one-sided (cell phone) conversation versus a two-sided conversation on attention and memory. In our realistic design, participants were led to believe they were participating in a study examining the relationship between anagrams and reading comprehension. While the participant was completing an anagram task, the researcher left the room and participants overheard a scripted conversation, either two confederates talking with each other or one confederate talking on a cell phone. Upon the researcher’s return, the participant took a recognition memory task with words from the conversation, and completed a questionnaire measuring the distracting nature of the conversation. Participants who overheard the one-sided conversation rated the conversation as significantly higher in distractibility than those who overheard the two-sided conversation. Also, participants in the one-sided condition scored higher on the recognition task. In particular they were more confident and accurate in their responses to words from the conversation than participants in the two-sided condition. However, participants’ scores on the anagram task were not significantly different between conditions. As in real world situations, individual participants could pay varying amounts of attention to the conversation since they were not explicitly instructed to ignore it. Even though the conversation was irrelevant to the anagram task and contained less words and noise, one-sided conversations still impacted participants’ self-reported distractibility and memory, thus showing people are more attentive to cell phone conversations than two-sided conversations. Cell phone conversations may be a common source of distraction causing negative consequences in workplace environments and other public places.

Brain activity during driving with distraction: an immersive fMRI study

Introduction: Non-invasive measurements of brain activity have an important role to play in understanding driving ability. The current study aimed to identify the neural underpinnings of human driving behavior by visualizing the areas of the brain involved in driving under different levels of demand, such as driving while distracted or making left turns at busy intersections.

Materials and Methods: To capture brain activity during driving, we placed a driving simulator with a fully functional steering wheel and pedals in a 3.0 Tesla functional magnetic resonance imaging (fMRI) system. To identify the brain areas involved while performing different real-world driving maneuvers, participants completed tasks ranging from simple (right turns) to more complex (left turns at busy intersections). To assess the effects of driving while distracted, participants were asked to perform an auditory task while driving analogous to speaking on a hands-free device and driving.

Results: A widely distributed brain network was identified, especially when making left turns at busy intersections compared to more simple driving tasks. During distracted driving, brain activation shifted dramatically from the posterior, visual and spatial areas to the prefrontal cortex.

Conclusions: Our findings suggest that the distracted brain sacrificed areas in the posterior brain important for visual attention and alertness to recruit enough brain resources to perform a secondary, cognitive task. The present findings offer important new insights into the scientific understanding of the neuro-cognitive mechanisms of driving behavior and lay down an important foundation for future clinical research.

Low-dose aspirin use and recurrent gout attacks

OBJECTIVE

To examine the association between cardioprotective use of low-dose aspirin and the risk of recurrent gout attacks among gout patients.

METHODS

We conducted an online case-crossover study of individuals with gout over 1 year. The following information was obtained during gout attacks: the onset dates, symptoms and signs, medications, and exposure to potential risk factors, including daily aspirin use and dosage, during the 2-day hazard period prior to the gout attacks. The same exposure information was also obtained over 2-day control periods.

RESULTS

Of the 724 participants analysed, 40.5% took aspirin ≤325 mg/day during either a hazard or a control period. Compared with no aspirin use, the adjusted OR of gout attacks increased by 81% (OR=1.81, 95% CI 1.30 to 2.51) for ≤325 mg/day of aspirin use on two consecutive days. The corresponding ORs were stronger with lower doses (eg, OR=1.91 for ≤100 mg, 95% CI 1.32 to 2.85). These associations persisted across subgroups by sex, age, body mass index categories and renal insufficiency status. Concomitant use of allopurinol nullified the detrimental effect of aspirin.

CONCLUSIONS

Our findings suggest that the use of low-dose aspirin on two consecutive days is associated with an increased risk of recurrent gout attacks. Recommended serum urate monitoring with concomitant use and dose adjustment of a urate-lowering therapy among patients with gout may be especially important to help avoid the risk of gout attacks associated with low-dose aspirin.

Impact of headway distance and car speed on drivers' decisions to answer an incoming call

OBJECTIVE

Previous studies on factors affecting drivers' decisions to use their mobile phones while driving are mostly focused on psychological and sociocultural contexts. Few investigations have been carried out on the role of traffic circumstances on drivers' decisions to use or not to use a mobile phone.

METHODS

In this research, the effects of headway distance, speed, and the type of road as well as individual variables including age and driving experience are investigated. Forty-two subjects participated in observing 24 scenarios in a driving simulator.

RESULTS

Logistic regression models showed that car speed, headway distance, and age can predict whether drivers' answer an incoming call while driving. The results indicated that traffic circumstances at the onset of phone calls are stronger predictors of drivers' decisions to answer a cell phone compared to driver-related variables.

CONCLUSIONS

Headway distance and car speed can be used by in-vehicle information systems (IVIS) to warn drivers against using a mobile phone in certain traffic situations. Traffic safety campaigns for young drivers should focus on keeping safe headway distance and speed while driving.

Influence of personal mobile phone ringing and usual intention to answer on driver error

Given evidence of effects of mobile phone use on driving, and also legislation, many careful drivers refrain from answering their phones when driving. However, the distracting influence of a call on driving, even in the context of not answering, has not been examined. Furthermore, given that not answering may be contrary to an individual's normal habits, this study examined whether distraction caused by the ignored call varies according to normal intention to answer whilst driving. That is, determining whether the effect is more than a simple matter of noise distraction. Participants were 27 young drivers (18-29 years), all regular mobile users. A Theory of Planned Behaviour questionnaire examined predictors of intention to refrain from answering calls whilst driving. Participants provided their mobile phone number and were instructed not to answer their phone if it were to ring during a driving simulation. The simulation scenario had seven hazards (e.g. car pulling out, pedestrian crossing) with three being immediately preceded by a call. Infractions (e.g. pedestrian collisions, vehicle collisions, speed exceedances) were significantly greater when distracted by call tones than with no distraction. Lower intention to ignore calls whilst driving correlated with a larger effect of distraction, as was feeling unable to control whether one answered whilst driving (Perceived Behavioural Control). The study suggests that even an ignored call can cause significantly increased infractions in simulator driving, with pedestrian collisions and speed exceedances being striking examples. Results are discussed in relation to cognitive demands of inhibiting normal behaviour and to drivers being advised to switch phones off whilst driving.

Driver performance while texting: even a little is too much

OBJECTIVE

To examine the impact of text messaging and other in-car behaviors on driving performance under simple and naturalistic road conditions in a driving simulator.

METHODS

Data from 28 healthy individuals (12 female) are presented. Participant age ranged from 18 to 28 (mean = 21.0). Average driving experience was 3.8 years (SD = 2.5). Participants completed a baseline loop condition in which they drove normally through a realistic virtual environment. Next, participants drove an identical loop, and at 3 specified points during this drive, participants were required to (1) complete a radio-tuning task; (2) type and send a text message containing "Drexel University"; and (3) type and send "I am driving to the store." Driving performance and task duration was compared between conditions.

RESULTS

Across all tasks, both lane management, F(1,27) = 11.1, P = .002, and velocity, F(1,27) = 10.3, P = .003, varied significantly more while task-engaged. Average lane deviation was significantly greater during a text messaging task than during the baseline drive of the same road segment, t(27) = -2.9, P = .007. Comparison of task durations indicated that both texting tasks took significantly longer to complete than the radio task, with the "Drexel University" text (118 s) taking almost twice as long as the radio-tuning task (60 s). Unexpected and novel findings emerged in the evaluation of duration of texting tasks using the varying text-entry methods, with touch-screen modality taking significantly longer than others.

CONCLUSIONS

Engaging in secondary tasks while operating a motor vehicle may have deleterious effects on driving performance and increase risk, even under the simplest of driving conditions. Text messaging may constitute a "perfect storm" of risk compared to other in-vehicle tasks such as tuning the car radio. The current investigation demonstrated detrimental effects of text messaging on driving behaviors such as lane maintenance, speed maintenance, and shifts of attention, even under relatively ideal and naturalistic driving conditions (e.g., familiar route, good weather, no traffic).

Impact of the penalty points system on severe road traffic injuries in Kuwait

OBJECTIVE

This study aimed to examine the effect of a penalty points system (PPS) implemented in early July 2006 on the number of severe road traffic injuries (RTIs) in Kuwait.

METHODS

Monthly counts of RTIs that occurred between January 2003 and December 2009 were analyzed. We used an interrupted seasonal autoregressive integrated moving average model (SARIMA) to estimate the intervention parameter along with its 95 percent confidence interval (CI) after accounting for seasonal and trend components in the data series. Based on the SARIMA model, we computed the number of RTIs that would have occurred post-PPS for 42 months after July 1, 2006, if it had not been implemented.

RESULTS

During the study period, a total of 4696 RTIs occurred. The Poisson rates of injuries (per 10 million of mean mid-year population and per 10 million of annual mean number of registered vehicles) were significantly (P < .001) lower in the post-PPS (λ(post-PPS) = 7 and 16, respectively) than the pre-PPS (λ(pre-PPS) = 9 and 23, respectively) implementation period. The intervention parameter's estimate was -7.68 (95% CI: -14.77, -0.60), suggesting that 322 (95% CI: 25, 620) individuals would have had RTIs in the 42 months post-PPS enactment, had it not been implemented. This translates to a 14.6 percent (95% CI: 1.1%, 28.0%) reduction.

CONCLUSIONS

These findings suggest that PPS implementation in Kuwait appears to have resulted in a significant reduction in the number of RTIs in the ensuing period. Therefore, PPS seems a feasible and effective approach in reducing RTIs in Kuwait and other countries in the region, if adequately implemented. Future studies may focus on evaluating the long-term effects of PPS implementation.

Couples, contentious conversations, mobile telephone use and driving

Studies have shown that the inappropriate use of in-vehicle technology may lead to hazardous disruption of driver performance. This paper reports an investigation into the socio-technical implications of maintaining a difficult conversation while driving. Twenty romantically involved couples participated in a driving-simulator experiment. The participants engaged in emotionally difficult conversations while one partner drove. The contentious conversation topics were identified using a revealed differences protocol, requiring partners to discuss sources of ongoing disagreement in their relationship. The conversations were conducted either using handsfree telephone or with both parties present in the simulator. Results indicate that the revealed differences tasks were subjectively viewed as emotionally more difficult than a control. Driver performance was found to be adversely effected for both longitudinal and lateral vehicle control. Performance was worst during contentious conversations with the partner present, suggesting the drivers may be better able to regulate driving task demands with the partner not in the vehicle during difficult discussions.

Mitigating the effects of in-vehicle distractions through use of the Psychological Refractory Period paradigm

Modern driving involves frequent and potentially detrimental interactions with distracting in-vehicle tasks. Distraction has been shown to slow brake reaction time and decrease lateral and longitudinal vehicle control. It is likely that these negative effects will become more prevalent in the future as advances are made in the functionality, availability, and number of in-vehicle systems. This paper addresses this problem by considering ways to manage in-vehicle task presentation to mitigate their distracting effects. A driving simulator experiment using 48 participants was performed to investigate the existence of the Psychological Refractory Period in the driving context and its effect on braking performance. Drivers were exposed to lead vehicle braking events in isolation (single-task) and with a preceding surrogate in-vehicle task (dual-task). In dual-task scenarios, the time interval between the in-vehicle and braking tasks was manipulated. Brake reaction time increased when drivers were distracted. The in-vehicle task interfered with the performance of the braking task in a manner that was dependent on the interval between the two tasks, with slower reactions following a shorter inter-task interval. This is the Psychological Refractory Period effect. These results have implications for driver safety during in-vehicle distraction. The findings are used to develop recommendations regarding the timing of in-vehicle task presentation so as to reduce their potentially damaging effects on braking performance. In future, these guidelines could be incorporated into a driver workload management system to minimise the opportunity for a driver to be distracted from the ongoing driving task.

Stuck in the 70s: the role of social norms in distracted driving

Successful campaigns to end distracted driving must understand prevailing social norms for behaviors such as texting and phoning while driving. The current work examined this issue by asking younger drivers to read car crash scenarios and rate the responsibility of the driver for the crash, and to levy fines and assign jail time, as a function of whether the driver was attentive, had been drinking, or was distracted by phoning or texting. In the first experiment, ratings were performed in the absence of injunctive norm information (laws against drunk and distracted driving). In the second experiment, injunctive norm information was included. Impaired drivers were viewed as more responsible in both experiments, with texting drivers viewed as the most responsible. However, drunk drivers received the most fines and jail time. When compared to data from the 1970s, the results show that anti-drunk driving campaigns have changed how younger drivers view drunk driving, but that norms have not yet changed for distracted driving, despite consistent results showing they know the risk of driving distracted. Implications for social norm distracted driving campaigns are discussed.

The Effects of Cell Phone Use and Automation on Driver Performance and Subjective State in Simulated Driving

Cell phone use has been identified as a threat to driver safety. Impairments may depend on the type of cell phone usage such as calling back and text messaging. The present study investigated whether the impact of phone use depends on the state of fatigue of the driver. A manipulation of full vehicle automation was used to induce a state of passive fatigue during a simulated drive. Participants were also assigned to one of four cell phone response conditions (Cell Phone, Text Message, Free-Choice or Control). Subjective responses, vehicle control and speed of response to an emergency event were assessed. Cell phone use did not mitigate stress and fatigue produced by vehicle automation. We also replicated existing findings that phone use, especially texting, impairs normal driving performance. However, phone use during automation was associated with a faster braking response following transition to normal control, suggesting that there may be circumstances under which phone use enhances alertness. Safety implications of the findings are discussed.

Driver Distraction: Effects of Text Entry Methods on Driving Performance

This research investigates the effect of cell phone interface design on simulated driving performance. The effects of three text message conditions (no text, touch screen keyboard, physical keyboard) on lateral vehicle control and operator workload (mental and physical) were evaluated. Twenty three participants performed a lane change task for each of the text message conditions. The results indicate that drivers had greater lane variability and reported higher workload when using a touch screen compared to physical keyboard. The findings of this study suggest that a touch screen interface may exacerbate the effects of a secondary task (e.g. texting) on driving performance.

Useful field of view predicts driving in the presence of distracters

PURPOSE

The Useful Field of View (UFOV) test has been shown to be highly effective in predicting crash risk among older adults. An important question which we examined in this study is whether this association is due to the ability of the UFOV to predict difficulties in attention-demanding driving situations that involve either visual or auditory distracters.

METHODS

Participants included 92 community-living adults (mean age 73.6 ± 5.4 years; range 65-88 years) who completed all three subtests of the UFOV involving assessment of visual processing speed (subtest 1), divided attention (subtest 2), and selective attention (subtest 3); driving safety risk was also classified using the UFOV scoring system. Driving performance was assessed separately on a closed-road circuit while driving under three conditions: no distracters, visual distracters, and auditory distracters. Driving outcome measures included road sign recognition, hazard detection, gap perception, time to complete the course, and performance on the distracter tasks.

RESULTS

Those rated as safe on the UFOV (safety rating categories 1 and 2), as well as those responding faster than the recommended cut-off on the selective attention subtest (350 msec), performed significantly better in terms of overall driving performance and also experienced less interference from distracters. Of the three UFOV subtests, the selective attention subtest best predicted overall driving performance in the presence of distracters.

CONCLUSIONS

Older adults who were rated as higher risk on the UFOV, particularly on the selective attention subtest, demonstrated poorest driving performance in the presence of distracters. This finding suggests that the selective attention subtest of the UFOV may be differentially more effective in predicting driving difficulties in situations of divided attention which are commonly associated with crashes.

Peer passengers: how do they affect teen crashes?

PURPOSE

The specific mechanisms by which peer passengers increase teen drivers' crash risk are not completely understood. We aimed to provide insight on the two primary hypothesized mechanisms, distraction and promotion of risk-taking behavior, for male and female teen drivers and further for select driver-passenger gender combinations.

METHODS

From the National Motor Vehicle Crash Causation Survey (2005-2007), we analyzed a nationally representative sample of 677 drivers aged 16-18 years (weighted n = 277,484) involved in serious crashes, to compare the risk of specific distraction-related and risk-taking-related precrash factors (documented via on-scene crash investigation) for teens driving with peer passengers and teens driving alone.

RESULTS

Compared with males driving alone, those with peer passengers were more likely to perform an aggressive act (risk ratio, RR [95% confidence interval] = 2.36 [1.29-4.32]) and perform an illegal maneuver (RR = 5.88 [1.81-19.10]) just before crashing; risk taking increased regardless of passenger gender. Crash-involved males with passengers were also more likely to be distracted by an exterior factor (RR = 1.70 [1.15-2.51]). Conversely, females with passengers were more often engaged in at least one interior nondriving activity (other than conversing with passengers) (RR = 3.87 [1.36-11.06]), particularly when driving with opposite-gender passengers. Female drivers, both with and without passengers, rarely drove aggressively or performed an illegal maneuver before crashing.

CONCLUSIONS

Passengers may affect male teen driver crashes through both distraction and risk-promoting pathways, and female involvement primarily through internal distraction. Results of this and future studies investigating peer-driver interactions may guide development of passenger-related crash prevention efforts to complement already existing Graduated Driver Licensing passenger restrictions.

Attentional effects on gaze preference for salient loci in traffic scenes

Alerting drivers for self-regulation of attention might decrease crash risks attributable to absent-minded driving. However, no reliable method exists for monitoring driver attention. Therefore, we examined attentional effects on gaze preference for salient loci (GPS) in traffic scenes. In an active viewing (AV) condition requiring endogenous attention for traffic scene comprehension, participants identified appropriate speeds for driving in presented traffic scene images. In a passive viewing (PV) condition requiring no endogenous attention, participants passively viewed traffic scene images. GPS was quantified by the mean saliency value averaged across fixation locations. Results show that GPS was less during AV than during PV. Additionally, gaze dwell time on signboards was shorter for AV than for PV. These results suggest that, in the absence of endogenous attention for traffic scene comprehension, gaze tends to concentrate on irrelevant salient loci in a traffic environment. Therefore, increased GPS can indicate absent-minded driving.

PRACTITIONER SUMMARY

The present study demonstrated that, without endogenous attention for traffic scene comprehension, gaze tends to concentrate on irrelevant salient loci in a traffic environment. This result suggests that increased gaze preference for salient loci indicates absent-minded driving, which is otherwise difficult to detect.

Cell phone use and crash risk: evidence for positive bias

BACKGROUND

Recent epidemiologic studies have estimated little or no increased risk of automotive crashes related to cell phone conversations by the driver, whereas earlier case-crossover studies estimated the relative risk as close to 4. Did earlier studies introduce a positive bias in relative risk estimates by overestimating driving exposure in control windows?

METHODS

Driving exposures in a "control" window and a corresponding "case" window on the subsequent day were tabulated across 100 days for 439 GPS-instrumented vehicles in the Puget Sound area during 2005-2006.

RESULTS

For control windows containing at least some driving, driving exposure was about one-fourth that of case windows. Adjusting for this imbalance reduces relative risk estimates in the earlier case-crossover studies from 4 to 1.

CONCLUSION

Earlier case-crossover studies likely overestimated the relative risk for cell phone conversations while driving by implicitly assuming that driving during a control window was full-time when it may have been only part-time.

Accidents and close call situations connected to the use of mobile phones

The aim of our work was to study the accidents and close call situations connected to the use of mobile phones. We have analyzed how the accidents/close call situations are connected to background information, in particular age, gender and self-reported symptoms. The study was carried out as a cross-sectional study by posting the questionnaire to 15,000 working-age Finns. The responses (6121) were analyzed using the logistic regression models. Altogether 13.7% of respondents had close call situations and 2.4% had accidents at leisure, in which the mobile phone had a partial effect, and at work the amounts were 4.5% and 0.4% respectively, during the last 12 months. Essentially, we found that: (1) men tend to have more close calls and accidents while on a mobile phone, (2) younger people tend to have more accidents and close calls while on a mobile phone, but it does not appear to be large enough to warrant intervention, (3) employed people tend to have more problems with mobile phone usage and accidents/close calls, and (4) there was a slight increase in mobile-phone-related accidents/close calls if the respondent also reported sleep disturbances and minor aches and pains. In the future, it is important to take into account and study how symptoms can increase the risk of accidents or close call situations in which a mobile phone has a partial effect.

An assessment of commercial motor vehicle driver distraction using naturalistic driving data

OBJECTIVE

This study analyzed naturalistic driving data from commercial trucks (3-axle and tractor-trailer/tanker) and buses (transit and motorcoach) during a 3-month period.

METHODS

The data set contained 183 commercial truck and bus fleets comprising 13,306 vehicles and included 1085 crashes, 8375 near crashes, 30,661 crash-relevant conflicts, and 211,171 baseline events. Study results documented the prevalence of tertiary tasks and the risks associated with performing these tasks while driving.

RESULTS

Results indicated the odds of involvement in a safety-critical event differed as a function of performing different cell phone-related subtasks while driving. Although the odds ratio for talking/listening on a cell phone while driving was found to not significantly increase the likelihood of involvement in a safety-critical event, other cell phone subtasks (e.g., texting, dialing, reaching) were found to significantly increase the odds of involvement in a safety-critical event.

CONCLUSIONS

The results suggest that cell phone use while driving should not be considered a simple dichotomous task (yes/no). Consideration should instead be made for a set of discrete cell phone subtasks that are each associated with varying levels of risk. Several hypotheses are presented to explain why cell phone use while driving was found to not increase the likelihood of involvement in a safety-critical event.

A comparison of the effect of mobile phone use and alcohol consumption on driving simulation performance

OBJECTIVE

The present study compared the effects of a variety of mobile phone usage conditions to different levels of alcohol intoxication on simulated driving performance and psychomotor vigilance.

METHODS

Twelve healthy volunteers participated in a crossover design in which each participant completed a simulated driving task on 2 days, separated by a 1-week washout period. On the mobile phone day, participants performed the simulated driving task under each of 4 conditions: no phone usage, a hands-free naturalistic conversation, a hands-free cognitively demanding conversation, and texting. On the alcohol day, participants performed the simulated driving task at four different blood alcohol concentration (BAC) levels: 0.00, 0.04, 0.07, and 0.10. Driving performance was assessed by variables including time within target speed range, time spent speeding, braking reaction time, speed deviation, and lateral lane position deviation.

RESULTS

In the BAC 0.07 and 0.10 alcohol conditions, participants spent less time in the target speed range and more time speeding and took longer to brake in the BAC 0.04, 0.07, and 0.10 than in the BAC 0.00 condition. In the mobile phone condition, participants took longer to brake in the natural hands-free conversation, cognitively demanding hands-free conversation and texting conditions and spent less time in the target speed range and more time speeding in the cognitively demanding, hands-free conversation, and texting conditions. When comparing the 2 conditions, the naturalistic conversation was comparable to the legally permissible BAC level (0.04), and the cognitively demanding and texting conversations were similar to the BAC 0.07 to 0.10 results.

CONCLUSION

The findings of the current laboratory study suggest that very simple conversations on a mobile phone may not represent a significant driving risk (compared to legally permissible BAC levels), whereas cognitively demanding, hands-free conversation, and particularly texting represent significant risks to driving.

Estimating Crash Risk

Naturalistic driving research involves the instrumentation of vehicles, including video cameras, for the purpose of precisely recording participants as they normally drive as well as in the seconds leading up to crashes and near-crashes. The results provide new insight into driver behavior and performance that cannot be gained through traditional empirical approaches. Naturalistic driving studies provide context of the overall driving environment, information that is absent from other methods. This article highlights how results from naturalistic driving research have reshaped our understanding of driver behavior and crash risk, including the fact that some findings are contrary to results from other empirical approaches.