How distraction affects pedestrian response: Evidence from behavior patterns and cortex oxyhemoglobin changes

ObjectivesDistracted walking is a major cause of pedestrian road traffic injuries, but little is known about how distraction affects pedestrian safety. The study was designed to explore how visual and auditory distraction might influence pedestrian safety.MethodsThree experiments were conducted to explore causal mechanisms from two theoretical perspectives, increased cognitive load from the distraction task and resource competition in the same sensory modality. Pedestrians’ behavior patterns and cortex oxyhemoglobin changes were recorded while they performed a series of dual tasks.ResultsFour primary results emerged: (a) participants responded more slowly to both visual and auditory stimuli in traffic, as well as walked more slowly, while talking on the phone or text messaging compared to when undistracted or listening to music; (b) when participants completed pedestrian response tasks while distracted with a high cognitive load, their response was significantly slower and poorer than when they carried out a lower cognitive load distraction task, (c) participants had higher levels of oxy-Hb change in cortices related to visual processing and executive function while distracted with a higher cognitive load; and (d) participants' responses to traffic lights were slower and resulted in a higher activation in prefrontal cortex and occipital areas when distracted by a visual distraction task compared to when distracted with an auditory task; similarly, brain activation increased significantly in temporal areas when participants responded to an auditory car horn task compared to when they responded to visual traffic lights.ConclusionsBoth distracting cognitive load demands and the type of distraction task significantly affect young adult pedestrian performance and threaten pedestrian safety. Pedestrian injury prevention efforts should consider the effects of the type of distracting task and its cognitive demands on pedestrian safety.     

手机分心对行人过街中信息加工及行为的影响

行人过街时, 因使用手机而造成的伤亡事故持续增长。过街时使用手机对行人信息加工、行为及安全均会产生影响。结果表明：使用手机的行人, 在场景知觉阶段注意范围更狭窄, 在外周视野的注意力明显下降; 过街决策阶段, 更容易错过过街机会或做出更有风险的决策; 运动控制阶段, 使用手机会改变行人步态, 降低其动作稳定性。以上效应还受到行人使用手机方式的调节, 但综合看来, 手机分心提升了行人过街风险, 更容易造成过街事故。最后, 通过建立手机分心对行人过街中信息加工及行为影响的概念模型, 指出未来研究应评估手机分心如何影响行人听觉信息的获取, 以及间隔接受决策的子过程, 从而为后期有针对性地干预提供理论基础。     

Effects of using mobile phones while cycling: A study from the perspectives of manipulation and visual strategies

Bicycles have become one of the major modes of urban public travel. Moreover, the high number of bicycle accidents has created challenges for road traffic safety. In addition, a relationship exists between single-handed use of handlebars and the use of mobile phones while cycling, which increases the risk of cycling. The current study considers not only the impact of mobile phone use while cycling on the safety of cyclists but also the impact of the mental load of a distracting task on cycling safety. Thirty-two college students were recruited to participate in a cycling experiment with distractions that was carried out on both campus and off-campus roads. A paired t-test was used to analyze cyclists' performance under different distraction states. The results show that when performing distracting tasks, the speed of cycling is significantly reduced, the acceleration and rate of change in the deflection angle are significantly increased, and the saccade frequency is significantly reduced. In addition, texting while cycling has a greater negative impact on cycling performance than does calling or listening to music. This study reveals the harm of mobile phone use while cycling by analyzing the effects and characteristics of manipulation performance and visual strategy. The study results can contribute to improving cyclist awareness regarding distraction safety and reducing the occurrence of mobile phone distraction issues. Furthermore, this approach provides a theoretical research basis for scientific and effective intervention and improvement measures in the future.     

The prevalence of in-vehicle driving distractions in road traffic collisions as a function of road type

While some previous research suggests that conversing with passengers is the most prevalent in-vehicle distraction while driving, others have concluded instead that it is mobile phone use. One possible explanation for these differences is that distraction prevalence varies with road type. To test this proposal the current study investigated the prevalence of in-vehicle driving distraction in road traffic collisions (RTCs) as recorded in national records from the US and New Zealand. Analysis using odds ratios suggested conversing with passengers to be a more prevalent distraction in RTCs on minor roads than on major roads, and mobile phone use to be a more prevalent distraction on major roads than on minor roads. These results show the importance of considering the type of road when investigating the prevalence of driving distractions in RTCs in future research.     

A systematic review of observational studies investigating the influence of mobile phone distraction on road crossing behaviour of pedestrians

The growing prevalence of technological distractions amongst pedestrians makes it an important road safety concern. Observational studies are considered a reliable method to investigate the influence of mobile phone distraction on pedestrian road crossing behaviour and crash risks. The present study conducts a systematic review of international literature on pedestrian distraction observations by following the Preferred Reporting Items for Systematic Reviews and meta-Analyses (PRISMA) guidelines. A total of 792 studies were identified from the literature search on six research databases: Scopus, Google Scholar, Web of Science, PubMed, Cochrane library, and Transportation Research International Documentation (TRID). Finally, 39 research articles were assessed using the systematic classification scheme based on the following five research aspects: prevalence of mobile phone distraction, study locations, performance measures, analysis techniques, and additional factors associated with mobile phone use among pedestrians. Over 35% of the studies were conducted in the United States of America (USA) and 69% of the investigations were done in the last five years. Overall, the findings across the studies indicate that mobile phone distraction plays a major role in pedestrian risky road crossing behaviour and violation tendencies. Visual distractions (such as texting) exhibited higher behavioural impairment compared to cognitive distractions (e.g., listening to music, and conversations). Pedestrian characteristics such as gender and age were the key factors examined in 77% and 67% of the observational studies. Finally, important directions for future research are illustrated to aid the researchers working in the area of pedestrian safety.     

The role of modality: Auditory and visual distractors in Stroop interference

As a commonly used measure of selective attention, it is important to understand the factors contributing to interference in the Stroop task. The current research examined distracting stimuli in the auditory and visual modalities to determine whether the use of auditory distractors would create additional interference, beyond what is typically observed in the print-based Stroop task. Research by Cowan and Barron supported the additive effects of auditory and visual distractors; however, there is only one empirical demonstration of this finding to date. Using different versions of the Stroop colour-naming task, behavioural analyses of reaction times (RT) were conducted, along with distributional RT analyses. The results indicated that a combination of visual and auditory distraction did not lead to a larger interference effect than visually based distraction alone. These findings suggest that methodological issues may have influenced the prior finding of additive effects of the two modalities, and are discussed in relation to the word production architecture account of Stroop effects.     

How drivers adapt their behaviour to changes in task complexity: The role of secondary task demands and road environment factors

The present study investigates the impact of different sources of task complexity such as driving demands and secondary task demands on driver behaviour. Although much research has been dedicated to understanding the impact of secondary task demands or specific road traffic environments on driving performance, there is little information on how drivers adapt their behaviour to their combined presence. This paper aims to describe driver behaviour while negotiating different sources of task complexity, including mobile phone use while driving (i.e., calling and texting) and different road environments (i.e., straight segments, curves, hills, tunnels, and curves on hills). A driving simulator experiment was conducted to explore the effects of different road scenarios and different types of distraction while driving. The collected data was used to estimate driving behaviour through a Generalized Linear Mixed Model (GLMM) with repeated measures. The analysis was divided into two phases. Phase one aimed to evaluate driver performance under the presence and absence of pedestrians and oncoming traffic, different lanes width and different types of distraction. The second phase analysed driver behaviour when driving through different road geometries and lane widths and under different types of distraction. The results of the experiment indicated that drivers are likely to overcorrect position in the vehicle lane in the presence of pedestrians and oncoming traffic. The effect of road geometry on driver behaviour was found to be greater than the effect of mobile phone distraction. Curved roads and hills were found to influence preferred speeds and lateral position the most. The results of this investigation also show that drivers under visual-manual distraction had a higher standard deviation of speed and lateral position compared to the cognitive distraction and the non-distraction condition.     

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.     

Pedestrian behaviors at and perceptions towards various pedestrian facilities: an examination based on observation and survey data

This paper presents findings from an observational study of pedestrian behaviors at various urban crosswalks and a pedestrian user survey which sought pedestrian perceptions toward various pedestrian facilities in a divided urban boulevard located next to a large university campus, Michigan State University, East Lansing, MI, USA. Such facilities included signalized and unsignalized intersection crosswalks, unsignalized marked and non-striped midblock crosswalks, physical barriers (vegetation and two-foot high concrete wall), midblock crosswalk shelters, colored paving (red brick pavement) at medians and curbs, and pedestrian warning signs at midblock crossing locations, messaging “cross only when traffic clears.” Pedestrian behavior data were obtained from the reduction of video images of pedestrian movements recorded throughout the study site. Pedestrian perceptions information was obtained through a user survey completed by pedestrians using the study site. It was found that unsignalized midblock crosswalks were the treatment of preference to pedestrians (83% reported a preference to cross) and also showed high crossing compliance rate of pedestrians (71.2%). It was also evident that the crosswalk location, relative to the origin and destination of the pedestrian, was the most influential decision factor for pedestrians deciding to cross at a designated location (90% said so). Proper traffic control can further encourage pedestrian crossings at designated locations since the effect of the availability of pedestrian signal to influence pedestrians’ decisions to cross at a specific location was quite high (74% said so). Moreover, vegetation and concrete barriers influenced the decision to cross of a significant number of pedestrians surveyed (65%). It is expected that the findings from this study will help traffic engineers, urban planners and policy makers understand pedestrian behaviors and attitudes at/towards pedestrian crosswalks.     

Mobile phone use while driving in Finland

Mobile phones represent one of the most common distractions for drivers and phone use while driving is particularly problematic in Finland. The aim of this research was to explore the Finnish sample of responses from ESRA2 (E-Survey of Road users' Attitudes) with a specific focus on the distracting behaviours related to mobile phone usage while driving. ESRA2 data is derived from online surveys amongst a representative sample of the adult populations in each participating country. In total a sample of 994 responses were collected in Finland for ESRA2, which included 703 responses from participants who held a driver’s licence and reported driving a car in the 30 days prior to the survey.The results provide evidence of the problematic usage of mobile phones while driving in Finland. Mobile phone use was considered across three specific types of usage: (1) handheld phone calls while driving; (2) handsfree phone calls while driving; (3) texting, emailing or social media use while driving. Almost half (49.4 %) of the sample reported using a handheld mobile phone to make a call while driving at least once in the 30 days prior to the survey. A similar percentage (41.4 %) of the sample had used a phone hands-free and 35.6 % had texted, emailed, or used social media.The study highlights how mobile phone usage is a complex and multifaceted issue and that there are a broad range of underlying factors that influence mobile phone usage depending on the way in which people engage with their mobile phone while driving. The findings suggest that a systematic approach to reducing mobile phone distraction is needed that addresses the issue through a combination of legislation, enforcement, and education.     

Changes in road-user behaviors following the installation of raised pedestrian crosswalks combined with preceding speed humps,on urban arterials

In this study, raised pedestrian crosswalks were installed at non-signalized mid-block crosswalks situated on urban arterial and collector roads. A raised crosswalk is built by installing a trapezoidal speed hump on the crosswalk area, building a preceding circular speed hump, in each travel direction, and adding traffic signs. A controlled field-study was conducted at eight sites, sixteen pedestrian crosswalks, where road user behaviors were compared in the after versus before the treatment periods. Two settings of raised crosswalks were applied at the study sites: a 15 cm high trapezoidal hump combined with 8–10 cm high circular humps, and a 10–12 cm high trapezoidal hump combined with 6–8 cm high circular humps. Field observations included video-recordings and free-flow speed measurements. Following the installation of the raised crosswalks, at most sites, a substantial decrease was observed in vehicle travel speeds while approaching the crosswalks, which was maintained over-time. In addition, at some crosswalks, improvements were found in the rates of giving-way to pedestrians by the vehicles, vehicle-pedestrian conflicts and shares of pedestrians who cross within the crosswalk boundaries, while the changes in keeping safe crossing rules by pedestrians were mixed. Overall, the changes in road user behaviors following the installation of the raised crosswalks were positive and associated with safety improvement of pedestrian crossing conditions. Based on the study results, raised crosswalks with preceding speed humps can be promoted as a pedestrian safety-improving measure on busy urban roads.     

The effects of operating a touch screen smartphone and other common activities performed while bicycling on cycling behaviour

Although it has been shown that making phone calls or sending text messages while riding a bicycle can have a negative impact on bicyclist’s behaviour, in countries such as the Netherlands the operation of a mobile phone while cycling on a bicycle is not illegal and is actually quite common. In recent years conventional mobile phones with a physical keypad are increasingly being replaced by smartphones with a touch screen. The operation of a touch screen phone ironically cannot be done purely ‘by touch’ due to the lack of tactile feedback, and instead requires fixations on a relatively small screen. The question therefore can be asked whether the operation of touch screen telephones deteriorates cycling behaviour more than operation of a conventional mobile phone.Twenty-four participants completed a track on their own bicycle while sending a text message from a conventional and a touch screen mobile phone. In addition the effects of other common activities that can accompany bicycling were studied, including texting at the same time as listening to music, talking on a mobile phone or cycling next to someone and speaking with this companion, and playing a game on a touch screen phone while bicycling. The impacts of all the above conditions on cycling performance and visual detection performance were compared with control conditions in which participants cycled with either one or two hands on the handlebars and were not required to perform any secondary tasks.Bicycle speed was reduced in all telephone conditions and in the condition when cycling next to someone. Lateral position variation increased in all telephone conditions. Use of the touch screen led to a more central position in the cycle lane and resulted in worse visual detection performance compared with the operation of a conventional mobile phone. The main effect of listening to music was that an auditory signal to stop cycling was missed by 83% of the participants. In conclusion, while all investigated types of phone deteriorated cycling performance, the use of a touch phone has a larger negative effect on cycling performance than a conventional mobile phone. With touch screen smartphones taking the place of conventional mobile phones and being used for other purposes than verbal communication, these effects on cycling performance pose a threat to traffic safety.     

The power and sensitivity of four core driver workload measures for benchmarking the distraction potential of new driver vehicle interfaces

This study evaluated the power and sensitivity of several core driver workload measures in order to better understand their use as a component of future driver distraction potential evaluation procedures of the in-vehicle human machine interface (HMI). Driving is a task that requires visual, manual and cognitive resources to perform. Secondary tasks, such as mobile phone use and interaction with in-built navigation, which load onto any of these three processing resources increase driver workload and can lead to impaired driving. Because workload and distraction potential are interrelated, a comprehensive method to assess driver workload that produces valid and predictive results is needed to advance the science of distraction potential evaluation. It is also needed to incorporate into New Car Assessment Program (NCAP) testing regimes. Workload measures of cognitive (DRT [Detection Response Task] Reaction Time), visual (DRT Miss Rate), subjective (NASA-TLX [driver workload questionnaire]), and temporal demand (Task Interaction Time) were collected as participants drove one of 40 vehicles while completing a variety of secondary tasks with varying interaction requirements. Of the evaluated measures, variance and power analyses demonstrated that Task Interaction Time is the most sensitive in detecting differences in driver workload between different in-vehicle HMIs, followed by DRT Miss Rate, NASA-TLX and finally DRT Reaction Time. There were relatively weak correlations between each of the four measures. These results suggest that Task Interaction Time, coupled with a reliable visual demand metric such as DRT Miss Rate, eye glance coding, or visual occlusion, more efficiently detect differences in driver workload between different HMIs compared to DRT Reaction Time and the NASA-TLX questionnaire. These results can be used to improve the understanding of the utility of each of these core driver workload measures in assessing driver distraction potential.     

Models for pedestrian gap acceptance behaviour analysis at unprotected mid-block crosswalks under mixed traffic conditions

Pedestrian safety is an important aspect while crossing the road and it can be explained by pedestrian gap acceptance behaviour. The statistical models such as multiple linear regression (MLR) is often used to model linear relationships between dependent variable (viz., pedestrian gap acceptance behaviour) and independent variables, due to their ability to quantitatively predict the effect of various factors on the dependent variable. However such linear models cannot consider the effect of several variables on the output variable, due to primary assumptions of normality, linear, homoscedasticity and multicollinearity. In this regard, the non-linear models based on the artificial neural network (ANN), which are free from assumptions of linear models, can be easily employed for obtaining the effect of several input variables on the pedestrian accepted gap size. However, researchers have rarely applied ANN modelling technique for predicting the pedestrian gap acceptance behaviour, as the pedestrian gap acceptance behaviour depends on several pedestrian, traffic and vehicular characteristics. The ANN based models would be quite useful in establishing relationship between these factors on the pedestrian gap acceptance behaviour at midblock crosswalks under mixed traffic conditions. In this direction, the present study adopts both MLR as well as ANN with different pedestrian, traffic and vehicular characteristics to assess the significant contributing factors for pedestrians’ gap acceptance behaviour at unprotected mid-block crosswalks under mixed traffic conditions. For this purpose, a video graphic survey was conducted at a six lane divided road at unprotected mid-block crossing in Mumbai, India. The data such as pedestrian (gender and age), vehicular, traffic and pedestrian behavioural characteristics were extracted to model pedestrian accepted gaps. The model results show that pedestrian rolling behaviour has a significant effect on pedestrian accepted gap size. The model results concluded that ANN has a better prediction with possibility to consider the effect of more number of variables on the pedestrian gap acceptance behaviour as compared to the MLR model under mixed traffic conditions. However, the quantification of significant contributing variables on pedestrian accepted gap size is easy by MLR model as compared to the ANN technique. So, both models have their own significant role in pedestrian gap acceptance analysis. The developed models may be useful to enhance the existing mid-block crosswalk facilities or planning new facilities by more accurate prediction of the pedestrian gap acceptance behaviour considering the influence of various factors under mixed traffic conditions.     

Bicyclists’ visual strategies when conducting self-paced vs. system-paced smartphone tasks in traffic

Visual distraction among cyclists interacting with their mobile phones is a growing concern. Yet, very little research has actually investigated how cyclists apply visual strategies and adapt task execution depending on the traffic situation. The aim of this study is to investigate visual behaviour of cyclists when conducting self-paced (initiated by the cyclist) vs. system-paced (initiated by somebody else) smartphone tasks in traffic.Twenty-two cyclists completed a track in real traffic while listening to music, receiving and making calls, receiving and sending text messages, and searching for information on the internet. The route and the types of tasks were controlled, but the cyclists could choose rather freely when and where along the route to carry out the tasks, thus providing semi-naturalistic data on compensatory behaviour.The results show that the baseline and music conditions were similar in terms of visual behaviour. When interacting with the phone, it was found that glances towards the phone mostly came at the expense of glances towards traffic irrelevant gaze targets and also led to shortened glance durations to traffic relevant gaze targets, while maintaining the number of glances. This indicates that visual “spare capacity” is used for the execution of the telephone tasks. The task type influenced the overall task duration and the overall glance intensity towards the phone, but not the mean nor maximum duration of individual glances. Task pacing was the factor that influenced visual behaviour the most, with longer mean and maximum glance durations for self-paced tasks.In conclusion, the cyclists used visual strategies to integrate the handling of mobile phones into their cycling behaviour. Glances directed towards the phone did not lead to traffic relevant gaze targets being missed. In system-paced scenarios, the cyclists checked the traffic more frequently and intensively than in self-paced tasks. This leads to the assumption that cyclists prepare for self-initiated tasks by for example choosing a suitable location. Future research should investigate whether these strategies also exists amongst drivers and other road user groups.     

Effects of pedestrian prompts on motorist yielding at crosswalks

Pedestrian safety is a serious concern at busy intersections and pedestrian campuses across the nation. Although crosswalks and signs inform pedestrians where to cross, there is no standard protocol for pedestrians to signal drivers that they wish to use the crosswalks, except to stand in or at the crosswalk. We examined the effects of two pedestrian prompts, a raised hand and extended arm, on motorist yielding at uncontrolled crosswalks. The two prompts were effective at increasing yielding.     

The influences of listening and speaking on pedestrians' assessments of approaching vehicles

Research suggests a relationship between auditory distraction (such as environmental noises or a vocal cell phone conversation) and a decreased ability to detect and localize approaching vehicles. What is unclear is whether auditory vehicle perception is impacted more by distractions reliant on listening or distractions reliant on speaking (analogous to the two components of a vocal cell phone conversation). In two experiments, adult participants listened for approaching vehicle noises and while performing listening- and speaking-based secondary tasks. Participants were tasked with identifying when they first detect an approaching vehicle and when they no longer felt safe to cross in front of the approaching vehicle. For both experiments, the speaking task resulted in significantly later detection of approaching vehicles and riskier crossing thresholds than in the no-distraction and listening conditions. The listening secondary task significantly differed from the control condition in experiment 1, but not experiment 2. Overall, our results suggest auditory distractions, particularly those reliant on speaking, negatively impact pedestrian safety in situations where visual information is minimal. Results may provide guidance for future research and policy about the safety impacts of secondary tasks.     

Happiness increases distraction by auditory deviant stimuli

Rare and unexpected changes (deviants) in an otherwise repeated stream of task‐irrelevant auditory distractors (standards) capture attention and impair behavioural performance in an ongoing visual task. Recent evidence indicates that this effect is increased by sadness in a task involving neutral stimuli. We tested the hypothesis that such effect may not be limited to negative emotions but reflect a general depletion of attentional resources by examining whether a positive emotion (happiness) would increase deviance distraction too. Prior to performing an auditory‐visual oddball task, happiness or a neutral mood was induced in participants by means of the exposure to music and the recollection of an autobiographical event. Results from the oddball task showed significantly larger deviance distraction following the induction of happiness. Interestingly, the small amount of distraction typically observed on the standard trial following a deviant trial (post‐deviance distraction) was not increased by happiness. We speculate that happiness might interfere with the disengagement of attention from the deviant sound back towards the target stimulus (through the depletion of cognitive resources and/or mind wandering) but help subsequent cognitive control to recover from distraction.     

Analysis of vehicle-based lateral performance measures during distracted driving due to phone use

Distracted driving due to mobile phone use has been identified as a major contributor to accidents; therefore, it is required to develop ways for detecting driver distraction due to phone use. Though prior literature has documented various visual behavioural and physiological techniques to identify driver distraction, comparatively little is known about vehicle based performance features which can identify driver’s distracted state during phone conversation and texting while driving. Therefore, this study examined the effects of simple conversation, complex conversation, simple texting and complex texting tasks on vehicle based performance parameters such as standard deviation of lane positioning, number of lane excursions, mean and standard deviation of lateral acceleration, mean and standard deviation of steering wheel angle and steering reversal rates (for 1°, 5° and 10° angle differences). All these performance measures were collected for 100 licensed drivers, belonging to three age groups (young, mid-age and old age), with the help of a driving simulator. Effects of all the phone use conditions and driver demographics (age, gender and phone use habits) on the measures were analysed by repeated measures ANOVA tests. Results showed that 1°, 5° SRRs are able to identify all the distracted conditions except for simple conversation; while, 10° SSR can detect all the distracted conditions (including simple conversation). The results suggest that 10° SRR can be included in intelligent in-vehicle devices in order to detect distraction and alert drivers of their distracted state. This can prevent mobile phone use during driving and therefore can help in reducing the road accidents due to mobile phone distractions.