Effects of personality on driving behaviors among professional truck drivers: The mediating effect of safety climate

Introduction: The number of traffic accidents involving truck drivers remains high, and strategies to eliminate the probability of such accidents have been proposed, among which enhancing the safety climate has attracted much interest. The main purpose of the current study was to validate the Chinese version of the safety climate scale for truck drivers and apply it to investigate the mediating effect of safety climate between truck driver personality and driving behavior. Method: A total of 389 male truck drivers completed the Big Five Inventory, the Chinese version of the trucking safety climate scale, the driver behavior questionnaire and the positive driver behavior scale. Results: The reliability and validity of the Chinese version of the organization-level safety climate scale and the group-level safety climate scale were confirmed through factor analysis. More importantly, a path analysis revealed that the organization-level safety climate mediated the effects of agreeableness and neuroticism on aggressive violations, ordinary violations and lapses, while the group-level safety climate mediated the influences of agreeableness, neuroticism and openness on positive behavior and all four kinds of aberrant driving behaviors. Conclusions: This study introduced the trucking safety climate scale into China and stressed the significance of improving both the organizational and the group levels of safety climate to reduce accidents involving professional truck drivers. Practical Applications: First, the adapted safety climate scale for Chinese truck drivers contributes to further investigating the role that safety climate plays in the safety problem of truck drivers in China. Moreover, the critical impacts of both levels of the trucking safety climate serve as reminders for relevant companies to not only pay attention to establishing an organization-level safety climate but also invest more effort into promoting the group-level safety climate.     

Investigating driving instructors: The mediating roles of driving skills in the relationship between organizational safety strategies and driver behaviours

The aim of the present study is to investigate the mediating roles of driving skills in relationship between organizational safety strategies and driver behaviours among driving instructors. Driving skills consist of perceptual-motor skills and safety skills. Driver behaviours are investigated under four factors: violations, errors, lapses, and positive driver behaviours. Participants were 132 driving instructors (108 male and 24 female). In order to measure organizational safety strategies, Organizational Safety Strategies Scale (OSSS) was developed for driving schools. Results of the principal component analyses yielded one-factor solution for OSSS. In order to test the indirect effects of organizational safety strategies on driver behaviours through driving skills, multiple mediation analyses were conducted by entering age and annual mileage as the control variables. As organizational safety strategies were stronger, driving instructors had higher levels of perceptual-motor skills, which resulted in higher violations. On the other hand, as organizational safety strategies were stronger, driving instructors had higher levels of safety skills, which resulted in less violations and lapses. It can be inferred that; organizational stronger safety strategies might have negative influences on road safety through higher perceptual-motor skills; whereas there can be positive influences on road safety through higher safety skills. In addition, both skills are related to organizational safety strategies. Hence, driving schools should consider the asymmetric relationship between perceptual-motor skills and safety skills while improving their safety strategies to decrease violations and lapses. Organizations might also develop interventions to balance the stated skills to increase road safety.     

Driving distraction at night: The impact of cell phone use on driving behaviors among young drivers

Currently, young drivers are more likely than other drivers to use cell phones while driving at night, which has become a major cause of road crashes. However, limited attention has been given to distracted nighttime driving. Therefore, the aim of this study was to explore the interaction effect of cell phone use and time of day (daytime and nighttime) on young drivers’ car-following performance. Forty-three young drivers engaged in a driving simulator experiment with a within-subject design that included three distractions (no distraction, talking and texting on a cell phone) and two times of day. This paper applied non-parametric tests to analyze the data and obtained the following results: (1) the standard deviation of lane position (SDLP) did not significantly differ at either time of day under no distraction, but it was significantly higher at night on straight roads and large-radius curves after introducing distractions. In addition, participants drove faster and gave less headway on small-radius curves under both distractions at night; (2) texting significantly increased the SDLP, while there was less lateral variation during the talking tasks than under no distraction on simple road sections; and (3) compared with the experienced drivers, the novice drivers drove faster during the talking tasks on small-radius curves, but there was no significant difference between groups during the texting tasks. These findings provide both theoretical and practical implications for related policy makers to enhance traffic safety.     

Supervisory interpretation of safety climate versus employee safety climate perception: Association with safety behavior and outcomes for lone workers

Research has shown that safety climate predicts safety behavior and safety outcomes in a variety of settings. Prior studies have focused on traditional work environments in which employees and supervisors work in the same location and the mechanisms through which safety climate affects behavior are largely understood. However, the nascent research examining safety climate among lone workers suggests that safety climate may have some uniqueness in this context. Based on leadership theories and utilizing an exploratory approach, this study increases our understanding of the lone worker context by examining employee perception of safety climate and supervisory interpretation of safety climate; how similar or different they are, and how they are related to important safety outcomes. Surveys were administered to a matched sample of 1831 truck drivers and their 219 supervisors at four different trucking companies. Objective data on employee injuries were collected six months after survey administration. The results provided support for the measurement equivalence of the Trucking Safety Climate Scale at the organization level for both employee and supervisor respondents. For both organization- and group-level safety climate, employee perceptions of safety climate and supervisory interpretation of safety climate were significantly different, such that supervisors provided higher ratings for both safety climate sub-scales. Further, only employee safety climate perceptions significantly predicted self-reported safety behavior (directly) and objective injury outcomes (indirectly). This suggests that when trying to gauge and improve upon a trucking company’s safety climate, we should rely on employee perspectives, rather than supervisory interpretation, of safety climate.     

An evaluation of the effectiveness of countermeasures for improving the safety of dilemma zones: A driving simulator study

The main objective of this driving simulator study is to analyze the behavior of the driver at the start of the yellow signal of a signalized rural intersection and identify the most effective countermeasures for tackling the dilemma zone, namely an area on the intersection approach where vehicles at the start of the yellow phase can neither safely stop before the stop line nor cross the intersection. The following countermeasures were tested in the study on a sample of 48 drivers: green signal countdown timers, GSCT (C₁); a new pattern of vertical and horizontal warning signs (C₂); and an advanced on-board driver assistance system based on augmented reality (AR) and connected vehicle technologies (C₃). These countermeasures were tested and compared to a baseline condition (B) where no countermeasures were applied. Based on the results of this study, the C₂ and C₃ countermeasures have proven to be valid tools for reducing driver indecision when approaching signalized intersections at the start of the yellow signal. In fact, using C₂ and C₃, the length of the dilemma zone was equal to 30 m and 36 m, respectively, with a reduction of about 50%, as compared to the baseline condition (B). Moreover, a reduced number of false behaviors was recorded, as well as a greater consistency in driver decision-making behaviors. Conversely, the C₁ countermeasure did not lead to a significant improvement in the dilemma zone: an unnecessary increase in early stop rates was recorded, resulting in reduced intersection efficiency and operations.     

Planning for driving retirement: The effect of driving perceptions,driving events,and assessment of driving alternatives

Most older adults will eventually stop driving, but few engage in planning for driving retirement. This study assessed whether driving stress, enjoyment, confidence, concerning driving events, and assessment of driving alternatives influence planning. Demographic factors were also included. Data were collected via a mailed transportation survey, with a final sample of 551 older adults who currently drive. Linear regression analyses revealed that more driving retirement planning was associated with greater driving stress, less driving confidence, and a more positive view of driving alternatives. Driving enjoyment and recent concerning driving events were not significantly related. Among the control variables, race and income were significantly related to planning, suggesting that lower income and identifying as Black race were associated with more planning. Gender only approached significance, suggesting that females may plan more than males. Overall, these findings suggest that more driving retirement planning is warranted. Some of the groups known to be at increased risk for driving reduction and cessation plan more for that eventuality than their counterparts. Implications of the study and suggestions for future research are discussed.     

The impact of sleep quality,fatigue and safety climate on the perceptions of accident risk among seafarers

IntroductionSeafaring is an extremely demanding profession that takes place in one of the most dangerous work environments possible. The unpredictable and demanding working conditions foster a high potential for risks and accidents.ObjectivesTo examine how sleep quality, fatigue and safety climate combine to influence perceptions of risk among seafarers.MethodParticipants were 151 seafarers working in the deck or machine departments on board 11 ships belonging to a Norwegian company. Questionnaires were administered at two different time points, approximately one week apart.ResultsPerceptions of risk of personal injuries and ship accidents increase when seafarers are fatigued. We also found that fatigue is related to poor sleep quality and that safety climate predicted both sleep quality and fatigue one week later.ConclusionsThe findings point to the importance for maritime organizations to be cognizant of the causes and consequences of fatigue among their employees, and that that policies and prioritizations are being perceived and interpreted by seafarers and may influence their sleep quality and vigilance when working at sea.     

The effects of safety knowledge and psychological factors on self-reported risky driving behaviors including group violations for e-bike riders in China

ObjectivesIt is unknown that how safety knowledge and psychological factors affect e-bike rider safety. Also, group violation behaviors, which are commonly observed in the field, have been rarely examined for e-bike riders in China. In this paper, the effects of safety knowledge and psychological factors on self-reported risky driving behaviors including group violations were examined.MethodsA questionnaire was developed to acquire information of e-bike riders in Guilin, Guangxi Province. Explanatory factor analysis was used to examine the reliability of the questionnaire and exclude redundant measurement items. Then, a Structure Equation Model was developed to examine the relationships among safety knowledge, safety attitude, risk perception and risky driving behaviors. After that, multiple regression models were fitted to examine the effect of safety knowledge on each type of risky driving behavior, as well as factors associated with group violations. At last, ANOVA tests were conducted to identify significant differences among e-bike rider groups in safety knowledge, safety attitude, and risk perception.ResultsSafety knowledge was found significantly associated with risky driving behaviors for e-bike riders in China, including aggressive driving, erroneous driving, and group violations. E-bike riders severely lack safety knowledge, especially that of traffic rules, including unmarried riders, under-educated riders, riders without driver’s license, younger riders, and riders with little riding experience. Group violations were largely found among e-bike riders, and to be associated with safety knowledge of traffic rules, risk-taking attitude, and riding experience of e-bike riders.ConclusionsThe findings could add some new safety implication and be beneficial for developing safety policies and interventions for e-bikes.     

Caffeine reduces the impact of drowsiness on driving errors

AimThe study examined the moderating effect of repeat-dose, chewing gum-administered caffeine on the well-established relationship between drowsiness and driving performance, under the conditions of accumulating sleep loss.Method50-h sleep deprivation protocol with a double-blind, placebo-controlled design. Eleven volunteers (6 male), aged 18–28 years were screened for pre-existing medical conditions (including sleep disturbances), tobacco and recreational drug use, recent time-zone travel and shift-work. They were randomly allocated to placebo or caffeine group and administered 4 oral doses of either caffeinated gum pellets (200 mg/dose) or non-caffeinated placebo gum every two hours (01:00, 03:00, 05:00, 07:00) on the first and second nights of the protocol. Participants were constantly monitored and remained awake for 50 h, while performing 15 identical, evenly-spaced 40-min monotonous driving tasks in a medium-fidelity moving-base driving simulator. Their drowsiness was monitored with a spectacle frame-mounted infra-red sensor registering ocular parameters and converting them into a Johns Drowsiness Scale (JDS) score every 60 s. Lane keeping and speed variability measures were used to assess driving performance.ResultsDriving performance declined and drowsiness increased from the first simulated drive to the last. When driving performance was examined in one-minute epochs synchronised with JDS scores, both lateral lane positioning and speed variability were found to be associated with drowsiness. The strength of this association was significantly weaker in the caffeine group, compared to placebo. Placebo group replicated the linear relationship between drowsiness and driving errors across the full range of JDS scores. This pattern was significantly weaker under the caffeine condition, and was even reversed at the upper range of JDS, with higher JDS scores not resulting in further degradation of driving performance. This dissociation between drowsiness and driving errors persisted across the 24-h cycle under the caffeine condition, despite caffeine being administered only during early morning hours.ConclusionStrategically timed, repeat 200 mg doses of caffeine administered via chewing gum can mitigate fatigue-induced impairments in driving performance by not only reducing drowsiness but also by significantly weakening its impact on driving errors. This dual effect of sustained drowsiness reduction and the dissociation between drowsiness levels and driving errors seems worth further investigation as it might offer an effective emergency countermeasure against driver drowsiness and its subsequent conversion into potentially fatal driving errors.     

The value of self-report measures as indicators of driving behaviors among young drivers

Although much of the knowledge in transportation psychology has been gained by means of self-report measures, there is still a dispute regarding the usefulness and validity of such instruments. This series of two studies employed multivariate statistical models to examine associations between self-report and objective measures in two samples of young drivers. Study 1 (n = 151) compared scores on the Multidimensional Driving Style Inventory (MDSI), a self-report questionnaire tapping four broad driving styles, with the naturalistic driving recorded by an in-vehicle data recorder (IVDR). Study 2 (n = 80) compared responses to the Reckless Driving Habits Scale, assessing the frequency with which drivers commit a set of risky behaviors, with driving measures collected by a simulator. This study also examined the personality trait of sensation seeking, as well as gender and driving experience. In Study 1, the analysis revealed positive associations between high scores on the risky and hostile driving styles measured by the MDSI and risky behaviors measured by the IVDR, as well as inverse correlations between the latter and high MDSI scores on the anxious and careful driving styles. Similarly, in Study 2 associations were found between the self-reported frequency of reckless driving habits and several risky behaviors measured by the driving simulator. In addition, risky behaviors correlated with the sociodemographic variables and sensation seeking. The two studies therefore show that self-report measures are reliable tools for assessing driving behaviors for purposes of research, evaluation, and intervention.     

Revised reinforcement sensitivity theory: The impact of FFFS and stress on driving

This study investigated the effect of a fear-based personality trait, as conceptualized in Gray’s revised reinforcement sensitivity theory (RST) by the strength of the Fight/Flight/Freeze system (FFFS), on young people’s driving simulator performance under induced psychosocial stress. Seventy-one young drivers completed the Jackson-5 questionnaire of RST traits, followed by a psychosocial stress or relaxation induction procedure (random allocation to groups) and then a city driving simulator task. Some support was found for the hypothesis that higher FFFS sensitivity would result in poorer driving performance under stress, in terms of significantly poorer hazard responses, possibly due to an increased attentional focus on the aversive cues inherent in the stress induction leaving reduced attentional capacity for the driving task. These results suggest that stress may lead to riskier driving behaviour in individuals with fearful RST personality styles.     

The effects of safety behaviors on health anxiety: an experimental investigation

The present study examined the extent to which safety behaviors exacerbate symptoms of hypochondriasis (severe health anxiety). Participants were randomized into a safety behavior (n = 30) or control condition (n = 30). After a baseline period, participants in the safety behavior condition spent one week actively engaging in a clinically representative array of health-related safety behaviors on a daily basis, followed by a second week-long baseline period. Participants in the control condition monitored their normal use of safety behaviors. Compared to control participants, those in the safety behavior condition reported significantly greater increases in health anxiety, hypochondriacal beliefs, contamination fear, and avoidant responses to health-related behavioral tasks after the safety behavior manipulation. In contrast, general anxiety symptoms did not significantly differ between the two groups as a function of the manipulation. Mediational analyses were consistent with the hypothesis that changes in the frequency of health-related thoughts mediated the effects of the experimental manipulation on health anxiety. These findings suggest that safety behaviors are associated with increases in health anxiety, perhaps by fostering catastrophic thoughts about health. The implications of these findings for the conceptualization of hypochondriasis as an anxiety disorder are discussed.     

Looking and thinking when driving: The impact of gaze and cognitive load on steering

Driving around bends at high speeds is a task performed by many on a daily basis but the underlying mechanisms of steering control remain largely unknown. Previous research has shown that when steering, gaze direction can be a critical component of success. However, with increased use of in-vehicle information systems (IVIS), there is growing competition over the same resources that are needed to steer (gaze as well as associated attentional resources). Although it can be argued that locomotor steering is an automatic task that can be performed without recourse to conscious “cognitive” control, much simpler locomotor-related tasks, such as judging one’s heading, have been shown to be affected by concurrent attentional tasks (Wann, Swapp, & Rushton, 2000). Here we examined whether an attentional task placed at an offset fixation point influenced concurrent steering performance along a computer simulated road. The experiments either used gaze-fixation points that had similar properties to real-world road signs (i.e. moved relative to the vehicle) or were more akin to IVIS (i.e. fixed to the vehicle). Results showed that gaze fixation eccentric to future path caused systematic steering biases. The degree or type of cognitive load did not change the degree of steering bias, but there was some evidence of decreased lane variability when viewing the IVIS-type displays. No differences in steering performance were found between the different types of cognitive task. We conclude that where you look is critical for safe driving, and IVIS-type displays might make drivers more susceptible to cognitive interference.     

The impact of cognitive functioning on driving performance of older persons in comparison to younger age groups: A systematic review

Older drivers are at a severely higher risk for motor vehicle crash involvement. Due to the global aging of the population, this increased crash risk has a significant impact on society, as well as on an older individual’s quality of life. For this reason, there is a need for understanding how normal age-related changes in cognition and underlying brain dynamics impact driving performance to identify the functional and neurophysiological biomarkers that could be used to design strategies to preserve or improve safe driving behavior in older persons. This review provides an overview of the literature on age-related changes in cognitive functioning and brain dynamics that impact driving simulator performance of healthy persons. A systematic literature search spanning the last ten years was conducted, resulting in 22 eligible studies. Results indicated that various aspects of cognition, most importantly executive function, complex attention, and dual tasking, were associated with driving performance, irrespective of age. However, there was a distinct age-related decline in cognitive and driving performance. Older persons had a more variable, less consistent driving simulator performance, such as more variable speed adaptation or less consistent lane keeping behavior. Only a limited number of studies evaluated the underlying brain dynamics in driving performance. Therefore, future studies should focus on implementing neuroimaging techniques to further unravel the neural correlates of driving performance.     

The impact of leaving a voicemail,environment familiarity,and pedestrian predictability on driving behavior

Talking on a cell phone can impair driving performance, but the dynamics of this effect are not fully understood. We examined the effects of leaving a voicemail message on driving when there are critical driving targets to attend to (crosswalks and pedestrians). Participants engaged in an ecologically-valid “voicemail” task while navigating a virtual environment using a driving simulator. We also examined the potential weakening or strengthening of effects of leaving a voicemail message on driving as the familiarity and predictability of critical targets changed. Participants completed four experimental runs through the same driving environment in a driving simulator. There were two crosswalks, one with a pedestrian entering the roadway and one without a pedestrian and the location of the pedestrian was predictable (the same pedestrian consistently used the same crosswalk) for the first three runs and then unpredictable for the fourth. Half of the participants left voicemail messages using a hands-free headset, while the other half drove in silence. Leaving a voicemail message increased steering deviation and velocity. Drivers who were leaving a voicemail message decelerated for pedestrians in the roadway to a similar speed as drivers who were not leaving a voicemail message, but they were delayed in braking. Drivers who were leaving a voicemail message also had worse memory for roadway landmarks. These effects were relatively stable across runs through the same driving environment, suggesting that familiarity and predictability did not impact the effects of leaving a voicemail message while driving. Therefore, leaving a voicemail message leads to poorer driving behavior; faster speed, variable steering, and worse memory for roadway landmarks. Interestingly, although drivers who were leaving a voicemail message were slower to react to local targets, they slowed as much as drivers who were not leaving a voicemail message and familiarity with the driving environment did not impact the effects of leaving a voicemail message on driving.     

Social exclusion affects aggressive driving behaviour: The mediating effect of prosocial tendencies and driving anger

Social exclusion—being rejected or ignored by individuals or groups—is a common and adverse experience in social life. As a social activity, driving behaviour can be influenced by many factors. Whether social exclusion is one of these factors is an open question. Therefore, the aim of this study is to explore the impact of the social exclusion experience on individuals and their driving behaviours and the mediating effect of prosocial tendencies and driving anger. A total of 240 (104 males and 136 females) participants from China completed a questionnaire including the Ostracism Experiences Scale (OES), the prosocial tendencies measure (PTM), the Driving Anger Scale (DAS) and the Driver Behaviour Questionnaire (DBQ). The hierarchical multiple regression analysis and pathway analysis results showed that social exclusion experience and driving anger positively predicted aberrant driving behaviours (including aggressive violations, ordinary violations, lapses and errors), while prosocial tendencies had a negative impact on aberrant driving behaviour. Moreover, prosocial tendencies and driving anger mediated the relationship between social exclusion and driver behaviour, accounting for 11.18% and 46.71% of the total effect, respectively. The chain-mediated effect of prosocial tendencies and driving anger was also significant, accounting for 5.26% of the total effect of social exclusion on driver behaviour. This study examines the mechanisms underlying social exclusion experiences that positively predict individuals' unsafe driving behaviours, thereby filling a gap in social exclusion research and suggesting new avenues of exploration into the personal and social influences that affect driving behaviours.     

The effects of safety behaviors on the fear of contamination: an experimental investigation

The strategies used by anxious individuals to prevent feared outcomes, known as safety behaviors, are thought to maintain pathological anxiety by preventing the disconfirmation of inaccurate threat beliefs. However, it is possible that safety behaviors might also contribute to the development and exacerbation of anxiety symptoms. The present study tested this notion in a sample of undergraduate participants with either low (n=30) or high (n=26) levels of contamination fear. After a week-long baseline period, participants spent 1 week engaging in a clinically representative array of contamination-related safety behaviors on a daily basis, followed by a second baseline period. Subsequent to the safety behavior manipulation, participants evidenced statistically significant increases in threat overestimation, contamination fear symptoms, and emotional and avoidant responses to three contamination-related behavioral avoidance tasks (BATs). In contrast, anxiety and depressive symptoms remained stable. The magnitude of change in contamination concerns was equivalent among participants in both contamination fear groups. Our findings suggest that contamination-related safety behaviors elicit a modest and specific increase in the fear of contamination. Possible mechanisms for this effect, as well as implications for the role of safety behaviors in the psychopathology of anxiety disorders, are discussed.     

Exploring the effects of the location of the lane-end sign and traffic volume on multistage lane-changing behaviors in work zone areas: A driving simulator-based study

The lane-changing behavior in work zone areas has special features than a regular lane change as the former is usually compulsively motivated involving complicated cognitive processes with drivers’ perception of work-zone control devices. Toward this end, this study conducted a driving simulator-based experiment to understand the effects of lane-end sign distance and traffic volume on driving behaviors. A conceptual model was also proposed to partition the whole lane-changing process into three stages, i.e. the perception, preparation and action stages, reflecting different cognitive and manipulative activities of drivers. In addition to the lane-end sign distance and traffic volume, gender and profession of drivers were adopted as covariates. In this experiment, a complete combination of lane-end sign distance and traffic volume served as treatments. The results verify the impacts of those factors on driving behaviors in and across different stages. For example, the location of the lane-end sign had a profound influence on drivers' perception of the imminent work-zone situation, but the influence continued to diminish in the following two stages. On the other hand, male or taxi drivers tended to act earlier than female or regular drivers respectively, for all the three stages. According to the analysis, several practical implications were also provided. In specific, the lane-end sign is recommended to be installed 500 m upstream to the lane dropping point of work zones. It is a pioneer study toward investigating multistage driving behaviors in work zone areas, which is expected to provide references and guidance for the design of traffic control devices and other driving simulator-based studies.     

The influence of road familiarity on distracted driving activities and driving operation using naturalistic driving study data

This paper analyzed the influence of familiarity on the involvement of secondary tasks and driving operation using naturalistic driving study (NDS) data. Distracted driving activities were extracted from face videos captured in 557 trips, including 501 trips on familiar roads and 56 trips on unfamiliar roads. These trips were completed by 155 drivers using their own vehicles during daytime hours under good weather conditions. The data showed the frequency of distracted driving activities and duration time were higher on familiar roads compared to unfamiliar roads. More types of secondary tasks were found on familiar roads. Focusing on objects was the most common distracted driving activity on familiar roads. The average time drivers used to eat or drink was highest (8.67 s) on familiar roads. The time drivers spent checking their cell phone was high on both familiar roads and unfamiliar roads. Since driving operation is directly related to crash risk, this paper also analyzed the difference of driving operation on familiar roads and unfamiliar roads. The speed profiles were generated on well-known versus unfamiliar roads. It was shown that drivers were more likely to be speeding and select a short distance to deceleration near the intersections. The findings indicated that distracted driving phenomenon was more serious on familiar roads.     

Effects of hands-free cellular phone conversational cognitive tasks on driving stability based on driving simulation experiment

Driver distraction due to cellular phone usage is a major contributing factor to road crashes. This study compares the effects of conversational cognitive tasks using hands-free cellular phone on driving performance under three distraction conditions: (1) no distraction (no cellular conversation), (2) normal conversation (non-emotional cellular conversation), and (3) seven-level mathematical calculations. A car-following scenario was implemented using a driving simulator. Thirty young drivers with an average age of 24.1 years maintained a constant speed and distance between the subject vehicle and a leading vehicle on the driving simulator, and then respond to the leading vehicle’s emergency stop. The driving performances were assessed by collecting and statistically analyzing several variables of maneuver stability: the drivers’ brake reaction times, driving speed fluctuation, car-following distance undulation, and car-following time-headway undulation. The results revealed that normal conversation on a hands-free cellular phone impaired driving performance. The degree of impairment caused by normal calculation was equivalent to the distraction caused by Level 3 mathematical calculations according to the seven-level calculation baseline. The calculation difficulty of Level 3 is one double-digit figure plus a single-digit figure, and non-carry addition mental arithmetic is required, e.g., 44 + 4. The results indicated that an increase in the level of complexity of the calculation task was associated with an increase in brake reaction time. The seven-level calculation-task baseline could be applied to measure additional distraction effects on driving performance for further comparison.