A close-up comparison of the misclassification error distance and the adjusted Rand index for external clustering evaluation

The misclassification error distance and the adjusted Rand index are two of the most common criteria used to evaluate the performance of clustering algorithms. This paper provides an in-depth comparison of the two criteria, with the aim of better understand exactly what they measure, their properties and their differences. Starting from their population origins, the investigation includes many data analysis examples and the study of particular cases in great detail. An exhaustive simulation study provides insight into the criteria distributions and reveals some previous misconceptions.     

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。     

A comparison of car following behaviors: Effectiveness of applying statistical quality control charts to design in-vehicle forward collision warning systems

This study aims to evaluate the usability of the forward collision warning (FCW) system as adopted by the statistical quality control (SQC) chart design concepts on drivers’ car following behaviors and task performance. A total of 48 highly aggressive and 48 less aggressive drivers participated in a two (aggressive driving: high vs. low; between-subjects) by two (driving workload: high vs. low; within-subjects) by three (the FCW system: five-stages vs. X-bar vs. X-bar plus exponentially weighted moving-average (EWMA) control charts; between-subjects) mixed-factorial simulation experiment. The drivers’ behaviors, response time to divided attention (DA) tasks, as well as subjective workload and trust ratings were collected. Findings showed that drivers with the FCW’s assistance improved their car-following behaviors and that the FCWs with the SQC chart design concepts showed better results than the five-stage system. Drivers who used both SQC FCWs performed correspondingly in their car-following behaviors. However, the X-bar FCW aided drivers in responding to DA tasks much faster, and drivers felt less stressed and had more trust in using the X-bar FCW system than those who used the X-bar + EWMA FCW system.     

The failure to respond to changes in the road environment: Does road familiarity play a role?

Road signs do not necessarily lead to the right response. Especially when signs are changed, drivers may not always detect new signs and may therefore fail to respond correctly to the situation indicated. The present driving simulator study investigated whether road familiarity (increased exposure to the same road) influenced failure to respond to a change in road signs. In order to study the failure to respond, participants were presented with a change in the road lay-out (as indicated by a road sign) in the last of a series of simulated drives. The change introduced was the conversion of a normal road into a No-Entry road. Results show that several participants failed to respond to this change. However, the failure to respond was not simply the result of familiarity with the road or prior exposure to precisely the same road, but seemed to be influenced by expectations induced by the road design. Additional safety measures such as the placement of additional road signs reduced the failure to respond. An auditory in-vehicle message gave the best results. Interestingly, both in the case of additional signs and of the in-vehicle message, a general warning was sufficient, without the need to specify the precise traffic situation.     

Using physiological and behavioral measurements in a picture-based road hazard perception experiment to classify risky and safe drivers

Every year, a considerable number of people got injured or even lost their lives in road traffic accidents. To decrease the number of fatalities and injuries, researchers are seeking methods to identify and restrain drivers before the happening of actual traffic accidents, who possess dangerous driving behaviors and may cause road traffic accidents. Such methods are usually exploited to decide drivers’ fitness to drive—an indicator to describe whether they are fit for driving. The aim of this study is to measure drivers’ physiological and behavioral responses to road hazards and to extract features from measurements for further classification of risky and safe drivers. 42 drivers participated in a picture-based road hazard perception experiment, where electroencephalography (EEG), electrodermal activity (EDA), behavioral responses to road hazards, multidimensional driving style inventory (MDSI) questionnaire, and demographic information were recorded. Results indicated that 5 specific physiological features regarding to road hazard perception showed significant differences between risky and safe drivers. Subsequently, participants were classified into risky or safe drivers group by applying only the 5 features. 81.82% and 77.78% accuracy of classification were attained for risky and safe drivers, respectively. It was evidenced that using physiological and behavioral responses to evaluate drivers’ road hazard perception might be utilized as a tool to measure drivers’ fitness to drive. For further studies, improvements to future experiment design were discussed.     

The role of legal and moral norms to regulate the behavior of texting while driving

Despite a nationwide lawful effort to regulate texting-while-driving behavior, little change has been reported. This study assessed the effect of current legal enforcement on attitudinal and behavioral responses toward texting while driving in conjunction with potential influences of two types of perceived norms—legal and moral. An online survey was conducted with 313 college students recruited from three states where the history of a banning law of texting while driving varied (more than 3 years, less than 1 year, and none). The students self-reported perceived legal norm, perceived moral norm, perceived risk of texting while driving, frequency of texting while driving, attitude toward texting while driving, and intention of texting while driving. General linear model analyses revealed that the mere presence of legal enforcement showed a negative relationship with frequency of behavior only for the state with the banning law in effect more than 3 years. While the perceived legal norm showed inconsistent relationships with outcome variables, the perceived moral norm appeared most promising to discourage texting while driving among young drivers. A banning law for texting-while-driving behavior not only backfired on the actual behavior in a short-term effect, but also required a long-term exposure of the law to change the actual behavior among college students. On the other hand, cultivation of a moral norm to regulate the behavior of texting while driving is particularly encouraged in that the stable nature of this psychological variable can play a role to suppress possible reactance evoked by an external force. Policy makers are encouraged to harness their approach to regulate young drivers’ texting while driving with the strategy that appeals to the drivers’ moral beliefs rather than simply forcing them to comply with the law.     

Characteristics of older cyclists (65+) and factors associated with self-reported cycling accidents in the Netherlands

Cycling supports the mobility, health and independency of the ageing population. However, older cyclists have an increased injury risk. On average, the risk of older people to sustain an injury in a cycling accident is three times higher per cycling kilometre than for middle-aged people and the injury risk increases with age. In comparison with middle-aged cyclists (<65 years), the risk of hospitalization is more than four times as high for older cyclists (≥65 years). The aim of this study was to reveal characteristics of older cyclists in general and to explore which of these characteristics are associated with self-reported cycling accidents from age 59. More than eight hundred older cyclists (>65 years) filled out a questionnaire, which included questions on demographics, bicycle specifications and personal characteristics. By means of a logistic regression, the relationship between personal factors and self-reported bicycle falls were studied. The univariate models showed that age, physical and mental impairments, bicycle model, living environment, feelings of uncertainty of the cyclist and changed cycling behaviour (such as more patience, lower speed) were related to falling off a bicycle. From the multivariate model we can conclude that several factors are associated with falling off a bicycle in the older population: (1) every year the cyclists becomes one year older (from the age of 65), the chance they have fallen increases with 7.3%, (2) If cyclists have mental impairments, the chance they have fallen increases with a factor 2.5, (3) if cyclists were less than completely confident the chance they have fallen increases with factor 1.8, (4) if cyclists live in a rural environment compared to an urban environment the chance they have fallen increases with a factor 2.1. In conclusion, demographic, cycling and personal factors can be related to increased self-reported fall risk. It is advised to take these factors into account when implementing new cycling related safety measures.     

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.