Detecting driver stress and hazard anticipation using real-time cardiac measurement: A simulator study

Exploring sleepiness and stress among London bus drivers: An on-road observational study

Bus driver sleepiness is commonplace but often goes unreported within the industry. Whilst past research has begun to shed a light on the prevalence, potential causes, and consequences of bus driver sleepiness, this is often done using self-report methods. This is the first study to investigate sleepiness amongst city bus drivers on-road using a live bus route with drivers' regular schedules. A total of 16 participants completed two drives of their regular bus route once during an early morning shift and once during a daytime shift whilst physiological and self-report measures of sleep and stress were taken. Prior to these drives, drivers recorded their sleep in a diary and wore an actigraph to obtain objective sleep measures. Results showed that most drivers did not obtain sufficient sleep prior to early morning shifts, and often did not obtain as much sleep as they would need in order to feel rested before work. Sleepiness and stress were observed in both shifts. During early morning shifts sleepiness was likely a result of working during circadian lows and not obtaining enough sleep prior to the shift. In contrast, sleepiness during the daytime shift was likely a result of completing a highly demanding task in complex traffic which not only contributed to fatigue, but also led to increased levels of stress. As well as demonstrating the prevalence of sleepiness amongst bus drivers, these findings show that the causes of sleepiness can be multifaceted and often come about due to a combination of work and personal factors. In addition, the experience of sleepiness is not the same for all drivers, with individual differences in the experience of sleepiness playing a large role. These differences highlight the need for individualised interventions which should be considered by policymakers alongside the combination of causal factors within a larger systems approach.

Effects of hazards and sensation-seeking on intermediate swimming college students' hazard perceptions

BACKGROUND

According to the Global Report on Drowning: Preventing a Leading Killer and Preventing Drowning: An Implementation Guide, two documents released by the World Health Organization in 2014 and 2017, respectively, 372,000 people drown each year globally (approximately 42 per hour), half of whom are below 25 years old. Chinese adolescents aged 18-24 years are the main victim group. Intermediate swimming college students are more susceptible to risk-taking behavior and drowning while swimming. In particular, college students with high-sensation-seeking levels have greater confidence in their swimming ability. Consequently, they tend to overestimate their skills and pursue exciting experiences while underestimating or ignoring the risk factors in the situation. The scores of college students in sensation-seeking show a significant positive correlation with highly risky swimming behavior. However, the correlation with the reaction time to hazards is unclear. In this study, using previous theories, the sensation-seeking scale, and the measurement of the reaction time to hazards, we clearly explain why "college students with higher levels of sensation-seeking have a higher risk of drowning." We examined the reaction time to hazards and eye movement data of intermediate swimming college students with different sensation-seeking levels, while controlling the obviousness of hazards in the videos for the experiment.

METHODS

We utilized 16 videos of students swimming as experimental stimuli and employed a mixed experimental design of 2 (sensation-seeking: high, low) × 2 (hazard type: obvious hazard, hidden hazard). Sensation-seeking, the between-subjects variable, was categorized into two levels (high and low). The hazard type, the within-subjects variable, was also divided into two categories (obvious and hidden). We analyzed the disparities in reaction time to hazards and eye-movement data between intermediate swimming college students with high (N = 28) or low (N = 28) levels of sensation-seeking.

RESULTS

Intermediate swimming college students with high levels of sensation-seeking exhibited significantly longer reaction times to both obvious (F = 6.251, p = .000 < .001) and hidden (F = 49.438, p = .000 < .001) hazards compared to their low-sensation-seeking counterparts. The first fixation duration of intermediate swimming college students on obvious hazards was shorter than that on hidden hazards (F = 13.596, p = .000 < .001), and the average fixation duration of intermediate swimming college students with high levels of sensation-seeking on hidden hazards proved to be significantly shorter (F = 5.498, p = .000 < .001).

CONCLUSIONS AND IMPLICATIONS

High-sensation-seeking intermediate swimming college students exhibited longer reaction times to hidden hazards compared to their low-sensation-seeking peers. These findings indicate that a high-sensation-seeking tendency can result in delayed reaction times and a disregard for response measures among intermediate swimming college students.

Exploring hazard anticipation and stress while driving in light of defensive behavior theory

In driving, poor hazard anticipation would provide drivers less time to prepare an appropriate response, increasing the urgency of the situation and generating more stress. Assuming this, the current study seeks to determine whether a predictable road hazard triggers hazard anticipation in drivers that can mitigate the ensuing stress response, and whether the stress response is influenced by driving experience. In a simulated road environment, a cue was used to trigger hazard anticipation, and a road hazard to induce a stress response. Heart rate, pupil diameter, driving speed, subjective stress, arousal, and negative emotions, were retrieved from 36 drivers who all faced the cue followed by the hazard (i.e. a predictable hazard), the cue only, and the hazard only. In the light of work on defensive behaviors, the findings indicate that a predictable hazard triggers hazard anticipation detectable via (1) freezing behavior-characterized by cardiac deceleration-(2) anticipatory pupil dilation and (3) anticipatory speed deceleration. The results also point to a beneficial role for hazard anticipation in reducing driver stress, as evidenced by reductions in peak heart rate levels, as well as in reported levels of stress and negative emotions. Finally, the findings showed an influence of driving experience on reported levels of stress. Overall, this study shows how previous work on defensive behaviors can be used to gain insight into the processes and driving behaviors involved in hazard anticipation and stress.

Being active over one's own motion: Considering predictive mechanisms in self-motion perception

Self-motion perception is a key element guiding pilots' behavior. Its importance is mostly revealed when impaired, leading in most cases to spatial disorientation which is still today a major factor of accidents occurrence. Self-motion perception is known as mainly based on visuo-vestibular integration and can be modulated by the physical properties of the environment with which humans interact. For instance, several studies have shown that the respective weight of visual and vestibular information depends on their reliability. More recently, it has been suggested that the internal state of an operator can also modulate multisensory integration. Interestingly, the systems' automation can interfere with this internal state through the loss of the intentional nature of movements (i.e., loss of agency) and the modulation of associated predictive mechanisms. In this context, one of the new challenges is to better understand the relationship between automation and self-motion perception. The present review explains how linking the concepts of agency and self-motion is a first approach to address this issue.