Car following with an inertia-oriented driving technique: A driving simulator experiment

BackgroundFor many decades, car-following (CF) and congestion models have assumed a basic invariance: drivers’ default driving strategy is to keep the safety distance. The present study questions that Driving to keep Distance (DD) is a traffic invariance and, therefore, that the difference between the time required to accelerate versus decelerate must necessarily determine the observed patterns of traffic oscillations. Previous studies have shown that drivers can adopt alternative CF strategies like Driving to keep Inertia (DI) by following basic instructions. The present work aims to test the effectiveness of a DI course that integrates 4 tutorials and 4 practice sessions in a standard PC computer designed to learn more adaptive driving behaviors in dense traffic. Methods. Sixty-eight drivers were invited to follow a leading car that varied its speed on a driving simulator, then they took a DI course on a PC computer, and finally they followed a fluctuating leader again on the driving simulator. The study adopted a pretest-intervention-posttest design with a control group. The experimental group took the full DI course (tutorials and then simulator practice). The control group had access to the DI simulator but not to the tutorials. Results. All participating drivers adopted DD as the default CF mode on the pre-test, yielding very similar results. But after taking the full DI course, the experimental group showed significantly less accelerations, decelerations, and speed variability than the control group, and required greater CF distance, that was dynamically adjusted, spending less fuel in the post-test. A group of 8 virtual cars adopting DD required less space on the road to follow the drivers that took the DI course.     

The relationship between simulator sickness and driving performance in a high-fidelity simulator

Driving simulators are highly valuable tools for various applications such as research, training, and rehabilitation. However, they are also known to cause simulator sickness, a special form of traditional motion sickness. Common side effects of simulator sickness include nausea, headache, dizziness, eye-strain, and/or disorientation, all symptoms which may negatively impact driving performance. The goal of the present study was to investigate the relationship between simulator sickness and driving performance obtained in a high-fidelity driving simulator. Twenty-one healthy participants were engaged in a simulated driving task containing rural, city, and highway sections for approx. 25 min. Participants were asked to drive naturally while obeying traffic rules and completing common driving maneuvers (including reactions to sudden events). Driving performance was evaluated based on various driving measures, such as lane positioning, speed measures, following distance, or the number of steering reversals. Simulator sickness was measured before, during, and after the simulated drive using a combination of the Simulator Sickness Questionnaire and the Fast Motion Sickness scale. Overall, correlations between the level of simulator sickness and driving performance measures were low to moderate (r’s from -0.37 to 0.40) and were not significant. Additionally, participants who reported higher levels of simulator sickness did not differ with regards to their driving performance from those who reported lower simulator sickness scores. Our results suggest that the presence of simulator sickness is not strongly related to performance in a driving simulator.     

Effects of specific emotions on subjective judgment,driving performance,and perceived workload

The aim of this paper was to explore effects of specific emotions on subjective judgment, driving performance, and perceived workload. The traditional driving behavior research has focused on cognitive aspects such as attention, judgment, and decision making. Psychological findings have indicated that affective states also play a critical role in a user’s rational, functional, and intelligent behaviors. Most applied emotion research has concentrated on simple valence and arousal dimensions. However, recent findings have indicated that different emotions may have different impacts, even though they belong to the same valence or arousal. To identify more specific affective effects, seventy undergraduate participants drove in a vehicle simulator under three different road conditions, with one of the following induced affective states: anger, fear, happiness, or neutral. We measured their subjective judgment of driving confidence, risk perception, and safety level after affect induction; four types of driving errors: Lane Keeping, Traffic Rules, Aggressive Driving, and Collision while driving; and the electronic NASA-TLX after driving. Induced anger clearly showed negative effects on subjective safety level and led to degraded driving performance compared to neutral and fear. Happiness also showed degraded driving performance compared to neutral and fear. Fear did not have any significant effect on subjective judgment, driving performance, or perceived workload. Results suggest that we may need to take emotions and affect into account to construct a naturalistic and generic driving behavior model. To this end, a specific-affect approach is needed, beyond the sheer valence and arousal dimensions. Given that workload results are similar across affective states, examining affective effects may also require a different approach than just the perceived workload framework. The present work is expected to guide emotion detection research and help develop an emotion regulation model and adaptive interfaces for drivers.     

A validation study of driving errors using a driving simulator

BackgroundDriving simulators have become an important research tool in road safety. They provide a safer environment to test driving performance and have the capacity to manipulate and control situations that are not possible on-road.AimTo validate a laboratory-based driving simulator in measuring on-road driving performance by type and mean driving errors.MethodsParticipants were instructed to drive a selected route on-road. The same route was programmed in the driving simulator using the UC/Win-road software. All participants completed a background questionnaire. On-road driving behaviours of participants and driving behaviours in the simulator were assessed by an occupational therapist and two trained researchers using an assessment form. Interclass correlations were calculated to assess the inter-rater agreement between the researchers on driving behaviours. Paired t-tests were used to assess differences in driving performance between the simulator and on-road assessments.ResultsA convenience sample of 47 drivers aged 18–69 years who held a current Western Australian class C licence (passenger vehicle) were recruited into the study. The mean age was 34.80 years (SD: 13.21) with twenty-six males (55.32%) and 21 females (44.68%) completing the study. There was no statistical difference between the on-road assessment and the driving simulator for mirror checking, left, right and forward observations, speed at intersections, maintaining speed, obeying traffic lights and stop signs.ConclusionThe preliminary results provide early support for the relative validity of the driving simulator which may be used for a variety of road safety outcomes with reduced risk of harm to participants.     

When grandparents drive their grandchildren

Driving their grandchildren has become one of the common tasks grandparents perform as part of the support they provide for working parents. The current research made use of qualitative and quantitative methodologies in two complementary studies conducted on grandparents who drive their grandchildren, the first using personal interviews and the second self-report questionnaires. The goal of the qualitative study was to capture grandparents’ subjective experience (n = 27), whereas the quantitative study sought to provide more specific data on the factors affecting grandparents’ experience behind the wheel and attitudes to child restraints by examining the contribution of driving styles and parental influence (n = 330). The findings of the qualitative study indicate that having grandchildren in the car is a unique situation which affects grandparents’ emotions and driving behavior. Less careful drivers were found to adapt a more careful driving style when driving their grandchildren than when driving without them. In the quantitative study, risky and anxious drivers felt more tension when driving their grandchildren. Furthermore, parental intervention was found to heighten tension among grandparents. Finally, heightened tension and less angry and more careful grandparents’ driving styles were associated with more positive attitudes to child restraints. Possible explanations of the findings are discussed.     

Cross-cultural perspective of driving style in young adults: Psychometric evaluation through the analysis of the Multidimensional Driving Style Inventory

Self-evaluating methods are frequently used to identify driving styles. Among others, one of the most commonly used questionnaires is the Multidimensional Driving Style Inventory (MDSI), developed for the Israeli population. Because of the extensive use of the questionnaire, the present paper aims to validate an Italian version and to confirm the 8-factor structure of the original one, i.e, dissociative, anxious, risky, angry, high-velocity, distress-reduction, patient, and careful driving style. The Italian version of the MDSI was filled out by 561 Italian drivers, who had a driving license for at least 1 year. A confirmatory factorial analysis (CFA) was conducted on the 44-item of the translated questionnaire showing not so good values of the goodness of fit tests (SRMR = 0.085; RMSEA = 0.063). The total-item correlation of each scale indicated that 4 items had a low index of total-item correlation. A second CFA was conducted on the remaining 40 items: goodness fit parameters improved (SRMR = 0.0685, RMSEA = 0.0584). Previous validations of the original version of MDSI for different populations (Argentine, Romanian, Chinese, Malaysian, Butch and Belgian) showed several critical issues in confirming the original structure. In the Italian version of MDSI validated in the present paper, the original 8-factor structure was confirmed by removing the 4 items which did not properly contribute to the factors. The results not only confirmed the usefulness of the MDSI in assessing driving style but they also indicated that the concept of driving style is considered in the same way in Italy and Israel, even though traffic rules are different. The latter consideration raises interesting questions for future research concerning cross-cultural comparisons of driving behavior in different countries.     

Differential effects of driver sleepiness and sleep inertia on driving behavior

ObjectivesDriver sleepiness is one of the major safety issues in conventional driving and sleep inertia emerges as a driver state in automated driving. The aim of the present study was to assess the differential impacts of sleepiness and sleep inertia on driving behavior.Method61 participants completed a 10-min manual driving task during an otherwise automated drive. They completed the task (a) under an alert state, (b) under a sleepy state, and (c) after EEG-confirmed sleep. Driving performance was assessed with the parameters lane-keeping, speed choice, and speed-keeping. The eye-blink-based sleepiness measure PERCLOS (the proportion of time with eyes closed) was compared for the three driver states.ResultsLane- and speed-keeping performance were impaired under the sleepy state and after sleep, relative to the alert state. After sleep, lane-keeping behavior recovered rapidly and speed-keeping recovered by trend. Under the sleepy state, performance deteriorated. After sleep, the mean speed was lower than in the sleepy state and in the alert state. PERCLOS was increased after sleep and under the sleepy state, relative to the alert state.ConclusionsAlthough sleep inertia had detrimental effects on driving parameters similar to sleepiness, this effect rapidly vanished. Hence, while brief naps might be suitable to restore alertness in general, the minimal time needed to regain full capacity after napping should be a focus of future research.     

Gender differences in the use of ADAS technologies: A systematic review

BackgroundIn recent years, Advanced Driving Assistance Systems (ADAS) have been significantly progressed, opening novel horizons in reducing traffic accidents. Driver gender can be an affecting factor in the utilization of these systems. The purpose of this study is to review articles examining the effect of gender on the use of ADAS technologies.MethodsThis systematic review was conducted in Scopus, Science Direct and PubMed databases using defined key-words in 2018. The retrieved articles were managed and screened through PRISMA-P protocol using EndNote X7 software. The extracted variables were divided into three categories of reaction, behavior, and outcome and also the relevant subgroups. The results for each subgroup were qualitatively and quantitatively analyzed to obtain a definite conclusion for each category.ResultsTotally, 1039 articles were retrieved from which 27 were included. The analysis of results in reaction category indicated that in almost all of the variables, there was no significant difference between male and female drivers. In the behavior category, gender showed a significant effect on variables within the subgroups of driving speed, longitudinal distance, and lateral motion. The gender had also significant effect on the variables of the outcome category.ConclusionsThe present review showed that there was no significant difference between male and female drivers in reaction to sudden traffic events alarmed by warning systems. However, in terms of driving behavior, males behaved more dangerous than female. The findings also revealed that the number of crashes in critical situations was higher for female drivers.     

Psychometric adaptation of the driving cost and benefit scale in Chinese drivers

The present study aimed to adapt the Driving Cost and Benefit Scale (DCBS, Taubman-Ben- Ari, 2008) to Chinese drivers and examine its relationships with driving style and traffic violations. Nine hundred drivers aged 18 to 60 years were asked to complete the DCBS and the Multidimensional Driving Style Inventory. The results of exploratory factor analysis (n = 429) and confirmatory factor analysis (n = 429) yielded a 36-item scale with satisfactory reliability. The Chinese version of the DCBS contains seven factors, including three driving cost factors (damage to self-esteem, life endangerment and distress) and four driving benefit factors (impression management, sense of control, thrill and pleasure). Significant associations between the DCBS-C factors and driving styles and traffic violations show that the discriminant validity of the scale is acceptable. Moreover, the driving cost factor of damage to self-esteem and the driving benefit factor of thrill both contributed to drivers’ traffic violations and crashes. The findings show that the reliability and validity of the Chinese version of the DCBS are acceptable, and it can be used as a tool to measure driving motivation in China.     

Behavioural adaptation to driving with an adaptive cruise control (ACC)

The present paper describes a study that aims at assessment of driver behaviour in response to new technology, particularly Adaptive Cruise Control Systems (ACCs), as a function of driving style. In this study possible benefits and drawbacks of Adaptive Cruise Control Systems (ACCs) were assessed by having participants drive in a simulator. The four groups of participants taking part differed on reported driving styles concerning Speed (driving fast) and Focus (the ability to ignore distractions), and drove in ways which were consistent with these opinions. The results show behavioural adaptation with an ACC in terms of higher speed, smaller minimum time headway and larger brake force. Driving style group made little difference to these behavioural adaptations. Most drivers evaluated the ACC system very positively, but the undesirable behavioural adaptations observed should encourage caution about the potential safety of such systems.     

The quiet passenger: Cognitions,avoidance, and onset among people with driving anxiety

BackgroundAnxiety over driving can have consequences for road safety and individual well-being. This area is under-researched in Australia, despite international research suggesting that most drivers experience some level of anxiety over driving.ObjectivesThis study aimed to contribute to the understanding of driving anxiety by 1) confirming the factor structure of two questionnaires designed to understand the concerns (Driving Cognitions Questionnaire: DCQ) and avoidance behaviours (Driving and Riding Avoidance Scale: DRAS); 2) providing evidence of anxiety manifestations in Australian drivers, and 3) understanding whether these differ according to the initial onset of this anxiety.MethodsA total of 1,600 people (77% females; age ranging from 18 to 89 [M = 27.92; ± 13.49], 75% licenced, 20% learning, 5% unlicenced) in Australia who identified as having “some” level of anxiety over driving, completed an online questionnaire regarding their anxiety.ResultsConfirmatory Factor Analyses showed the two-factor structure of the DRAS (general and traffic avoidance; and weather and riding avoidance) and the two-factor structure of the DCQ (crash-related concerns and social and panic related concerns) best fit the data. The most common anxiety onsets were crash involvement (14%), knowing someone who had been in a crash (9%) and due to criticism from others (9%). While no differences emerged between these groups on avoidance behaviour nor on crash concerns, social and panic concerns were higher for the criticism onset group.ConclusionsThe results demonstrate difference sources of anxiety and provide evidence of the importance of interactions with passengers in determining how a driver feels about the driving task.Practical implicationsAvenues for the reduction or avoidance of anxiety are proposed. These include better awareness and education for drivers regarding the importance of positive interactions and/or well as better journey management to avoid triggers of anxiety.     

Cognitive behavior therapy for driving fear: A pilot randomized controlled trial

Fear of driving is common in clinical practice, while its treatment programs are understudied. This is the first randomized controlled trial to evaluate a newly developed protocol for cognitive behavior therapy (CBT) for driving fear compared with a wait list and to use specific assessment scales. 34 participants (30 women, 4 men) in an outpatient psychotherapy clinic were randomly allocated to either 18 sessions of CBT or a wait list (n = 17 each). After treatment, CBT was significantly more efficacious than the wait list with large effect sizes on the Instrument for Fear of Driving (IFD) (Cohen’s d = 2.58) and on the Driving Cognitions Questionnaire (DCQ) (Cohen’s d = 2.14). Driving fear is a condition treatable by CBT and the suggested protocol is safe, feasible and acceptable. Further studies with larger samples and active controls (e.g., virtual reality therapy) are required to draw generalizable conclusions on effect sizes.     

Young driver distraction by text messaging: A comparison of the effects of reading and typing text messages in Chinese versus English

BackgroundReading and typing text messages while driving seriously impairs driving performance and are prohibited activities in many jurisdictions. Hong Kong is a bilingual society and many people write in both Chinese and English. As the input methods for text messaging in Chinese and English are considerably different, this study used a driving simulator approach to compare the effects of reading and typing Chinese and English text messages on driving performance.MethodThe driving performances of 26 participants were monitored under the following conditions: (1) no distraction, (2) reading and typing Chinese text messages, and (3) reading and typing English text messages. The following measures of driving performance were collected under all of the conditions: reaction time (RT), driving lane undulation (DLU), driving speed fluctuation (DSF), and car-following distance (CFD) between test and leading cars.ResultsRT, DLU, and DSF were significantly impaired by reading and typing both Chinese and English text messages. Moreover, typing text messages distracted drivers more than reading them. Although the Chinese text messaging input system is more complicated than the English system, the use of Chinese did not cause a significantly different degree of distraction.ConclusionBoth reading and typing text messages while driving should be prohibited regardless of whether Chinese or English is used.     

How does emotional intelligence predict driving behaviors among non-commercial drivers?

Dangerous driving behaviors have been found to be a leading contributor to vehicle crashes and fatalities, with more than 2.7 million people injured and 36,560 people killed in the United States in 2018 (NHTSA, 2020). Drivers’ emotions have been found to be among the leading contributors to dangerous driving behaviors. Emotions can be measured and understood through one’s emotional intelligence (EI). Previous research has confirmed the relationship between EI and dangerous driving behaviors among general driving populations in limited scope. This study analyzed dangerous driving behaviors (e.g., aggressive driving) among non-commercial US drivers. 615 US drivers ages 18 to 65 (M = 31.14, SD = 11.15) with valid US driver’s licenses (non-commercial) participated in this study. Participants completed an online survey through Qualtrics that included the Trait Emotional Intelligence Questionnaire (TEIQue-SF) to measure different dimensions of EI and the Dula Dangerous Driving Index (DDDI) and the Driving Behavior Questionnaire (DBQ) to measure dangerous driving behaviors. Furthermore, participants reported their demographic information, including age, sex, and location. Correlation analysis revealed that significant associations exist between dangerous driving behaviors and EI. The emotionality component of EI was found to be the strongest predictor of dangerous driving behaviors. The findings concluded that participants with higher EI scores engaged in less dangerous driving behavior, resulting in fewer crashes and fatalities. Thus, promoting and improving EI may be useful in preventing risky driving among non-commercial drivers. Incorporating emotional intelligence education in driver’s education, workplace training, and licensing procedures can be helpful to develop safer drivers. Further research is needed to investigate commercial drivers’ behaviors in relation to EI.     

Effects of partial sleep deprivation: A comparative assessment of young non-professional and professional taxi drivers

AimThis study aims to determine the effects of partial sleep deprivation (PSD) on driving performance of professional and young non-professional drivers.MethodsThe study included fifty participants (20 professional taxi drivers and 30 young non-professional drivers) driving the simulator-cab in three conditions. The first test session (TS1) was conducted after one night of PSD followed by the second test (TS2) after two consecutive nights of PSD. The driving performance metrics in two conditions of PSD (i.e., sleep duration = 4.25 ± 0.5 h) were compared with the baseline drive with no sleep loss. Sleep restriction was monitored using Actiwatch. Drivers subjectively self-reported their alertness using Karolinska Sleepiness Scale (KSS). Driving performance metrics and reaction time to emergency events were collected during each drive.ResultsA preliminary mixed-design ANOVA showed deterioration in driving performance of all drivers in terms of speed (p < 0.1), speed variability (p = 0.06), standard deviation in lateral positions (SDLP) (p < 0.001) and delayed reaction time (p < 0.05). Separate Mixed-Effects Generalized Linear Models for professional and non-professional drivers showed that speed variability, SDLP and reaction time increased from baseline during both the PSD tests, among both the driving groups. The speed variability, SDLP and reaction time of professional drivers differed significantly from other drivers under PSD conditions. Contrary to the existing belief, the professional drivers had significant decrements in driving performance due to PSD.ConclusionA critical and comparative analysis revealed that driving experience/skill of professional drivers does not improve their resistance to deteriorating effects of sleep loss.     

Evaluating the impact of real-time coaching programs on drivers overtaking cyclists

Innovative motor insurance schemes involve the use of on-board devices to collect kinematic driving data as part of the so-called ‘Pay-How-You-Drive’ schemes, which charge premiums based on drivers’ behavior. Some of these schemes also involve on-board coaching programs, which give real-time feedback to users.Here, we aimed to investigate the influence of motor insurance on-board real-time coaching programs on drivers’ behavior while overtaking cyclists, as motor vehicle/bicycle interactions are a relevant issue in road safety. The tested programs give real-time feedback to users on their acceleration, promoting smoother and safer driving styles.Data were collected with a driving simulator experiment involving 67 young drivers. The experiment was divided into two trials: in the first, participants drove as normally as possible without receiving any type of feedback; in the second, which took place one month later, they received feedback based on their driving behavior. Using data from the first trial, participants were clustered (k-mean approximation) into two groups, according to their driving style (aggressive vs. defensive). For each group, half of the drivers received contingent positive feedback (when a smooth driving event occurred) and the other half received contingent negative feedback (when a harsh driving event occurred). Feedback was presented in the form of auditory cues (for half of one group) or as visual cues (for the others). Thus, there were eight groups based on driving style, feedback type, and feedback modality.Multiple kinematic variables were studied with mixed ANOVA, and included not only clearance distances, speeds, and acceleration, but also the chosen overtaking strategy (accelerative vs. flying). Driving style, gender, car usage, feedback type and modality were considered as factors in the analysis.Results showed that the coaching programs had a significant positive effect, in terms of safety, reducing acceleration and speeds during the overtaking and inducing drivers to adopt the safer accelerative strategy. It was also particularly effective in improving the performance of aggressive drivers. These results are of high interest for real-world applications because they were obtained with a general-purpose coaching program; conversely, it might be impractical to develop dedicate programs for specific situations such as drivers overtaking cyclists.     

A study identifying the origins of different types of drink driving events through the lens of deterrence: Is it alcohol abuse or avoiding detection?

BackgroundWhile attempts to identify the mechanisms to effectively deter drink driving remains a central focus for road safety researchers, scant scientific enquiry has simultaneously examined perceptions of apprehension risk in combination with substance abuse. This may be considered a significant oversight given that such constructs may create opposing forces, or alternatively, alcohol abuse and punishment avoidance may create cumulative effects and promote offending behaviours.MethodThis paper reports on an investigation of 718 Queensland motorists' self-reported perceptions of classical and reconceptualised deterrence constructs (as well as alcohol consumption) in order to determine what factors have the greatest effect on promoting drink driving, particularly alcohol consumption or punishment avoidance. The sample completed an online or paper version of the questionnaire.Results“Possible” drink driving events were slightly more common (25.5%) than “acknowledged” drink driving events (16.6%). Future intentions to drink and drive (23.4%) were more common among those who reported an “acknowledged” drink driving event (63.5% reported future intentions to drink drive) than a “possible” drink driving event (47.5%). Sequential binary logistic regression models conducted for each drink driving category revealed that having “risky” drinking behaviour and both direct personal and indirect experience of punishment for a drink driving offence were predictors of “possible” drink driving events. Similarly, “acknowledged” drink driving had the same significant predictors with the addition of increases in age and punishment severity reducing the likelihood of drink driving and direct punishment avoidance having a positive effect. However, and importantly, only direct punishment avoidance and past “possible” and “acknowledged” drink driving events predicted future intentions to offend in the final model, which further reinforces that drink driving is a deliberate decision (rather than stemming primarily from impairment).Practical applications: The findings provide support for increased policing efforts to identify drink drivers.     

Driving errors,estimated performance and individual characteristics under simulated and real road traffic conditions – A validation study

BackgroundThe suitability of driving simulators for the prediction of driving behaviour in road traffic has been able to be confirmed in respect of individual assessment parameters. However, there is a need for overarching approaches that take into account the interaction between various influencing factors in order to establish proof of validity. The aim of this study was to explore the validity of our driving simulator in respect of its ability to predict driving behaviour based on participants‘ observed driving errors and driver’s individual characteristics.Method41 healthy participants were assessed both in a Smart-Realo-Simulator and on the road. By means of linear modelling, the correlation between observed driving errors was investigated. In addition, the influence of self-reported and externally assessed driving behaviour as well as individual parameters (education and training; driving history) were analysed.ResultsBy including these factors, 58% of the variance could be explained. For observed driving errors, a relative validity was established. For self-reported and externally assessed driving behaviour, an absolute to relative validity emerged. The amount of time spent in education and training proved to have a significant influence on driving performance in the simulator, but not on the road.DiscussionIn general, our results confirmed the validity of our driving simulator with regard to observed and self-reported driving behaviour. It emerged that education and training as potential indicators of cognitive resources played a differential role regarding the study conditions. Since real road driving is considerably automated in experienced drivers, this result suggests that simulation-related behavioural regulation is challenged by additional cognitive demands as opposed to behavioural regulation extending to real road driving. However, the source of these additional cognitive demands remains currently elusive and may form the subject of future research.     

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.     

Associations between sedentary behavior and negative emotions in adolescents during home confinement: Mediating role of social support and sleep quality

BackgroundProlonged periods of sedentary behaviour, for instance, engendered by home confinement in Shenzhen city, has led to negative mental health consequences, especially in adolescents. Previous research suggests, in general, that sedentary behavior can increase negative emotions. However, the specific mechanism driving the relationship between sedentary behavior and negative emotions is still relatively unclear. Social support and sleep quality might partly explain the effect of sedentary behavior on negative emotions. Thus, the current study aimed to examine the associations between sedentary behavior and negative emotions, and to investigate if social support and sleep quality mediate such a relationship.MethodDuring home confinement due to the COVID-19 Omicron variant outbreak, 1179 middle and high school students in Shenzhen were invited to voluntarily complete an e-questionnaire, including the 21-item Depression Anxiety Stress Scale (DASS-21), the short form of the International Physical Activity Questionnaire (IPAQ-SF), the Social Support Rating Scale (SSRS) and the Pittsburgh Sleep Quality Index (PSQI). Data from 1065 participants were included in the analysis.ResultsWe observed significant sex-related and demografic-related differences in emotional (e.g., anxiety, stress and social support) and other outcome variables (e.g., sitting duration and PSQI score). Furthermore, sedentary behavior, social support, and sleep quality were associated with negative emotions (p < .01), even after controlling for sex, age, only-child case, body mass index, and metabolic equivalent level. In addition, social support and sleep quality partially mediated the association between sedentary behavior and negative emotions.ConclusionThe findings of the current study suggest that social support and sleep quality partially mediate the relationship between sedentary behavior and negative emotions in middle and high school students during home confinement in Shenzhen city.