Young and older adult pedestrians' behavior when crossing a street in front of conventional and self-driving cars.

Self-driving vehicles are gradually becoming a reality. But the consequences of introducing such automated vehicles (AVs) into current road traffic cannot be clearly foreseen yet, especially for pedestrian safety. The present study used virtual reality to examine the pedestrians' crossing behavior in front of AVs as compared to conventional cars (CVs). Thirty young (ages 21-39) and 30 older (ages 68-81) adults participated in a simulated street-crossing experiment allowing for a real walk across an experimental two-way street. Participants had to cross (or not cross) in mixed traffic conditions where highly perceptible AVs always stopped to let them cross, while CVs did not brake to give them the right of way. Available time gap (from 1 to 5 s), approach speed (30 or 50 km/h), and the lane in which the cars were approaching (near and/or far lane of the two-way street) were varied. The results revealed a significantly higher propensity to cross the street, at shorter gaps, when AVs gave way to participants in the near lane while CVs were approaching in the far lane, leading to more collisions in this condition than in the others. These risky decisions were observed for both young and older participants, but much more so for the older ones. The results also indicated hesitation to cross in front of an AV in both lanes of the two-way street, with later initiations and longer crossing times, especially for the young participants and when the AVs were approaching at a short distance and braked suddenly. This study highlights the potential risks for pedestrians of introducing AVs into current road traffic, complicating the street-crossing task for young and older people alike. Future studies should look further into the role of repeated practice and trust in AVs. The design of these vehicles must also be addressed. Some practical recommendations are provided.

Street-crossing workload in young and older pedestrians.

Although several studies have sought to identify both gap-acceptance difficulties with aging and gait differences, few have examined the extent to which crossing the street is physically and cognitively demanding for older pedestrians, in such a way that street crossing can be seen as a dual task. To gain insight into this issue, this study reports an experiment with 15 young (ages 19-26), 19 younger-old (ages 60-72), and 21 older-old (ages 73-82) adults. The participants carried out three tasks: (i) a simple walking task, (ii) a dual task involving walking while scanning (walking while pressing a button as soon as a visual or sound stimulus appeared), and (iii) a street-crossing task with vehicles approaching from two directions. The results indicated more street-crossing collisions in older-old than in younger-old and young participants. Longer reaction times were observed in the dual walking-scanning task for both old groups, especially for visual stimuli. Walking-speed comparisons yielded nonsignificant differences between the dual task and the street-crossing task in young participants, suggesting a correspondence in terms of demands and task priority. In contrast, old participants walked significantly faster in the street-crossing task than in the dual task, suggesting that they placed priority on walking rapidly than on scanning traffic. Finally, whereas the participants estimated the perceived workload to be greater when they were crossing the street than while simply walking or responding to the dual task, young participants gave the highest rating to the mental and physical demands, perhaps due to a lack of awareness of task demands among old participants.

A vibrotactile wristband to help older pedestrians make safer street-crossing decisions.

INTRODUCTION: Older pedestrians are overrepresented in fatal accidents. Studies consistently show gap-acceptance difficulties, especially in complex traffic situations such as two-way streets and when vehicles approached rapidly. In this context, the present research was aimed at assessing the effectiveness of a vibrotactile device and study older pedestrian's behavior when wearing the wristband designed to help them make safer street-crossing decisions. METHOD: Twenty younger-old participants (age 60-69), 20 older-old participants (age 70-80) and 17 younger adults (age 20-45) carried out a street-crossing task in a simulated two-way traffic environment with and without a vibrotactile wristband delivering warning messages. RESULTS: The percentage of decisions that led to collisions with approaching cars decreased significantly when participants wore the wristband. Benefits tended to be greater particularly among very old women, with fewer collisions in the far lane and when vehicles approached rapidly when they wore the wristband. But collisions did not fall to zero, and responses that were in accordance with the wristband advice went up to only 51.6% on average, for all participants. The wristband was nevertheless considered useful and easy to use by all participants. Moreover, behavioral intentions to buy and use such a device in the future were greater in both groups of older participants, but not among the younger adults. PRACTICAL APPLICATIONS: This haptic device was able to partly compensate for some age-related gap-acceptance difficulties and reduce street-crossing risks for all users. These findings could be fruitfully applied to the design of devices allowing communication between vehicles, infrastructures, and pedestrians.

Training the elderly in pedestrian safety: Transfer effect between two virtual reality simulation devices.

OBJECTIVES: A virtual-reality training program has been developed to help older pedestrians make safer street-crossing decisions in two-way traffic situations. The aim was to develop a small-scale affordable and transportable simulation device that allowed transferring effects to a full-scale device involving actual walking. METHODS: 20 younger adults and 40 older participants first participated in a pre-test phase to assess their street crossings using both full-scale and small-scale simulation devices. Then, a trained older group (20 participants) completed two 1.5-h training sessions with the small-scale device, whereas an older control group received no training (19 participants). Thereafter, the 39 older trained and untrained participants took part in a 1.5-h post-test phase again with both devices. RESULTS: Pre-test phase results suggested significant differences between both devices in the group of older participants only. Unlike younger participants, older participants accepted more often to cross and had more collisions on the small-scale simulation device than on the full-scale one. Post-test phase results showed that training older participants on the small-scale device allowed a significant global decrease in the percentage of accepted crossings and collisions on both simulation devices. But specific improvements regarding the way participants took into account the speed of approaching cars and vehicles in the far lane were notable only on the full-scale simulation device. DISCUSSION: The findings suggest that the small-scale simulation device triggers a greater number of unsafe decisions compared to a full-scale one that allows actual crossings. But findings reveal that such a small-scale simulation device could be a good means to improve the safety of street-crossing decisions and behaviors among older pedestrians, suggesting a transfer of learning effect between the two simulation devices, from training people with a miniature device to measuring their specific progress with a full-scale one.

Review of safety and mobility issues among older pedestrians.

Although old people make up an extremely vulnerable road-user group, older pedestrians' difficulties have been studied less extensively than those of older drivers, and more knowledge of this issue is still required. The present paper reviews current knowledge of older-adult problems with the main components of pedestrian activity, i.e., walking and obstacle negotiation, wayfinding, and road crossing. Compared to younger ones, old pedestrians exhibit declining walking skills, with a walking speed decrease, less stable balance, less efficient wayfinding strategies, and a greater number of unsafe road crossing behaviors. These difficulties are linked to age-related changes in sensorial, cognitive, physical, and self-perception abilities. It is now known that visual impairment, physical frailty, and attention deficits have a major negative impact on older pedestrians' safety and mobility, whereas the roles of self-evaluation and self-regulation are still poorly understood. All these elements must be taken into consideration, not only in developing effective safety interventions targeting older pedestrians, but also in designing roads and cars. Recent initiatives are presented here and some recommendations are proposed.

Towards an explanation of age-related difficulties in crossing a two-way street.

Crossing a two-way street is a complex task that involves visual, cognitive and motor abilities, all of which are known to decline with ageing. In particular, older pedestrians may experience difficulties when crossing two-way streets because of incorrect gap acceptance choices and impossible or unperceived evasive actions. To understand the overrepresentation of older pedestrians in crash statistics, several experimental studies have sought to identify traffic-related factors as well as those related to the abilities of the individuals themselves. However, none of these studies has required participants to actually walk across an experimental two-way street with curbs, which is a particularly challenging situation for older pedestrians. To fill this research gap, a quasi-experiment was conducted in a simulator including a total of 58 healthy aged participants (25 younger-old [age 60-72] and 33 older-old [age 72-92]) and 25 young adults (aged 18-25 years). Participants carried out a street-crossing task in a simulated two-way traffic environment; curbs were present on both sides of the experimental street. Participants also undertook a battery of tests to assess their visual and cognitive abilities. In addition, during the experiment, the participants' gait parameters were recorded. In line with earlier findings, the older-old group of participants made a higher number of decisions that led to collisions with approaching cars compared with the other groups. The two groups of older participants experienced specific difficulties when vehicles were in the far lane or when they approached rapidly. A regression analysis identified visual acuity, speed of processing (assessed using the UFOV(®) test), and step length as significant predictors of collisions. Our results have implications for understanding the difficulties experienced by older pedestrians and allow to draw up several recommendations for improving their safety.

Is Mild Dementia Related to Unsafe Street-Crossing Decisions?

The overrepresentation of very old people (75 or older) in pedestrian crash statistics raises the issue of the effects of normal and pathologic ageing on gap-selection difficulties during street crossing. The present study focused on Alzheimer disease, a condition commonly associated with cognitive declines detrimental to daily life activities such as crossing the street. Twenty-five participants with mild dementia and 33 controls carried out a street-crossing task in a simulated environment. They also took a battery of cognitive tests. The mild-dementia group was more likely than the control group to make decisions that led to collisions with approaching cars, especially when the traffic was coming from 2 directions and they were in the far lane. Regression analyses demonstrated that the increased likelihood of collisions in the dementia group was associated with impairments in processing-speed and visual-attention abilities assessed on the Useful Field of View test. This test has already proven useful for predicting driving outcomes, falls, and street-crossing difficulties in healthy old adults, and among drivers with Alzheimer disease. Clinicians are encouraged to use it to help estimate whether a patient can drive, walk, and cross a street safely.

Crossing a two-way street: comparison of young and old pedestrians.

INTRODUCTION: Choosing a safe gap in which to cross a two-way street is a complex task and only few experiments have investigated age-specific difficulties. METHOD: A total of 18 young (age 19-35), 28 younger-old (age 62-71) and 38 older-old (age 72-85 years) adults participated in a simulated street-crossing experiment in which vehicle approach speed and available time gaps were varied. The safe and controlled simulated environment allowed participants to perform a real walk across an experimental two-way street. The differences between the results for the two lanes are of particular interest to the study of visual exploration and crossing behaviors. RESULTS: The results showed that old participants crossed more slowly, adopted smaller safety margins, and made more decisions that led to collisions than did young participants. These difficulties were found particularly when vehicles approached in the far lane, or rapidly. Whereas young participants considered the time gaps available in both lanes to decide whether to cross the street, old participants made their decisions mainly on the basis of the gap available in the near lane while neglecting the far lane. CONCLUSIONS: The present results point to attentional deficits as well as physical limitations in older pedestrians. Several practical and have implications in terms of road design and pedestrian training are proposed.

Functional declines as predictors of risky street-crossing decisions in older pedestrians.

The experiment investigated the extent to which risky street-crossing decisions by older pedestrians can be explained by declines in functional abilities. Sixteen young (age 20-35), 17 younger-old (age 60-67), and 18 older-old (age 70-84) participants carried out a street-crossing task in a simulated two-way road environment and took a battery of tests assessing perceptual, cognitive, and motor abilities. Older-old pedestrians were more likely than young and younger-old participants to make decisions that would have led to collisions with approaching cars, especially when traffic coming from two directions was approaching at a high speed. Regression analyses identified several functional performance measures as predictors of these dangerous choices. Walking speed, which determined the time needed to cross, was shown to play the most important role. Time-to-arrival estimate, which informed the pedestrians about the time available for crossing, was found to be the second most predictive factor. Visual processing speed and visual attention abilities assessed via the UFOV® Test also came into play, allowing participants to focus their attention on the relevant available information and to make timely, correct decisions. Attention shifting was the fourth significant predictor, allowing pedestrians to adapt their crossing strategy to the oncoming road-traffic information. The results suggest that the greater risk of being involved in a collision as age increases calls for a multi-dimensional explanation combining age-related physical, perceptual, and cognitive performance declines. These findings have implications for improving older pedestrians' safety in terms of speed limits, road design, and training.

Age-related differences in street-crossing safety before and after training of older pedestrians.

International accident statistics indicate that elderly pedestrians make up an extremely vulnerable road-user group. Past research has shown that older adults make many unsafe street-crossing decisions and adopt insufficient safety margins, especially when vehicles are approaching at high speed. Apart from studies on road design and speed-limit countermeasures, there is surprisingly no road-safety research on behavior-based measures to improve older pedestrians' safety. In this line, the present study was aimed at (i) assessing the effectiveness of a training program for older pedestrians that combined behavioral and educational interventions, and (ii) examining whether and to what extent age-related differences in street-crossing safety could be reduced after training older adults. Twenty seniors were enrolled in a training program. Before, immediately after, and six months after training, street-crossing behavior was assessed using a simulated street-crossing task. Twenty younger participants performed the same simulated task to obtain a baseline measure. The results showed that the training produced significant short- and long-term benefits, due to a shifting of the decision criteria among the older participants towards more conservative judgments. When compared with the younger group, the older participants improved their behavior considerably so that significant differences in the mean safety-related indicators were no longer observed. However, the older participants' ability to take the oncoming car's speed into account did not improve. Even after training, and contrary to younger adults, older participants were found to make more and more unsafe decisions as the car's speed increased, putting them at a higher risk at high speeds. This finding may reflect age-related perceptual and cognitive difficulties that cannot be remedied by a behavioral or educational training method. The present findings underline that high speed is an important risk factor for elderly pedestrians that should be handled by effective speed reduction measures (i.e. speed ramps, road narrowing).

The role of perceptual, cognitive, and motor abilities in street-crossing decisions of young and older pedestrians.

PURPOSE: The present experiment investigated the role of perceptual, cognitive, and motor abilities in street-crossing behaviour with ageing. Previous research has shown that older pedestrians make many unsafe crossing decisions when cars are approaching at high speeds, and miss many crossing opportunities when car speeds are low. The older subjects seem to ignore information about the speed of the approaching cars and to preferentially use simplifying heuristics based on vehicle distance. The objective of the present study was to better understand the underlying age-related changes that lead to these behaviours, with a specific focus on perceptual factors. METHOD: Twenty young (age 20-30), 21 younger-old (age 61-71), and 19 older-old (age 72-83) participants took part in the experiment. All participants individually carried out a simulated street-crossing task and took a battery of functional tests assessing perceptual, cognitive, and motor abilities. RESULTS: In line with earlier findings, the seniors made a greater number of incorrect crossing decisions, with many risky decisions when the vehicle was approaching at a high speed and many missed opportunities at a low speed. Correlation and regression analyses pointed out several functional performance measures as predictors of the way the pedestrians took or did not take information about vehicle speed into account in their decisions. Processing speed and visual attention abilities were shown to play the most important role in explaining the variance in incorrect decisions: these abilities allowed participants to focus their attention on the relevant speed information and to make timely, correct decisions. Time-to-arrival estimates, which informed the pedestrians about the time available for crossing, were found to be the second most predictive factor. Walking speed, by way of which the pedestrians adapted their crossing pace to the perceived available time, also came into play. Inhibition abilities ended up as the last functional predictor; they allowed the pedestrians to ignore irrelevant information and inhibit automatic but unsuitable responses. CONCLUSIONS: The present study provided a multidimensional explanation of increased gap-selection difficulties with ageing, including a combination of perceptual, cognitive, as well as physical performance declines with increasing age. The findings have implications for improving older pedestrians' safety in terms of speed limits, road design, and training.

Searching for information on the World Wide Web with a search engine: a pilot study on cognitive flexibility in younger and older users.

This pilot study investigated the age-related differences in searching for information on the World Wide Web with a search engine. 11 older adults (6 men, 5 women; M age=59 yr., SD=2.76, range=55-65 yr.) and 12 younger adults (2 men, 10 women; M=23.7 yr., SD=1.07, range=22-25 yr.) had to conduct six searches differing in complexity, and for which a search method was or was not induced. The results showed that the younger and older participants provided with an induced search method were less flexible than the others and produced fewer new keywords. Moreover, older participants took longer than the younger adults, especially in the complex searches. The younger participants were flexible in the first request and spontaneously produced new keywords (spontaneous flexibility), whereas the older participants only produced new keywords when confronted by impasses (reactive flexibility). Aging may influence web searches, especially the nature of keywords used.

Seniors' perceived driving skill in a postlicense training program: comparison of instructors' assessments and self-assessments by seniors' age and sex.

This exploratory study was carried out during a postlicense training program for senior drivers. The aim was to study driving-ability assessments made by 37 older drivers and by instructors, according to age (< 72 yr.; > 72 yr.) and sex. After an open-road test course, both the older drivers' self-assessments and the instructors' assessments were collected on an ad hoc questionnaire that considered both general and specific aspects of driving ability. The seniors' ratings of their own driving ability were consistent with the instructors' ratings, at both levels considered. For general driving ability, men were evaluated more positively than were women, both by themselves and by the instructors. For specific aspects of driving, men got higher ratings than did women for driving on roundabouts. Concerning driving on four-lane roads, men in the younger senior group (< 72 yr.) were assessed more positively than were women in that group, whereas no significant gender-related difference was found among the older seniors. Concerning visual skills, the younger participants assessed their own visual skills more positively than did the older participants. In contrast, the instructors' assessments of the younger and older seniors were not significantly different. The results are discussed in terms of possible ways of improving training programs for licensed senior drivers.