Trial-by-trial feedback fails to improve the consideration of acceleration in visual time-to-collision estimation

Correction: Trial-by-trial feedback fails to improve the consideration of acceleration in visual time-to-collision estimation

[This corrects the article DOI: 10.1371/journal.pone.0288206.].

The efficacy of training to improve road safety in elderly pedestrians: A systematic review

Elderly pedestrians are involved in disproportionately more vehicle-pedestrian crashes than younger age groups. Training programs have been found to be effective in training children in pedestrian behaviours that improve their safety, however there is no consensus on whether older adults benefit from training. This systematic review aimed to identify whether training is effective for older adult pedestrians through analysis of training type, modalities, and the lasting effects of training. A systematic search of Medline, PsycINFO, and Scopus was conducted in March 2022 and updated in September 2023. Eight studies met the criteria all of which were high quality. Four distinct training types were found: physical (e.g., training physical strength or balance), behavioural (e.g., training specific pedestrian safety behaviours), cognitive (e.g., training reaction time and executive functioning), and educational (training knowledge about pedestrian safety behaviours). Physical training types were found to be most effective, followed by behavioural, cognitive, and educational respectively. Twelve pedestrian behaviours were measured across the eight studies. Reaction time was the most effectively trained outcome, followed by missed crossing opportunities. Errors of stimuli, median accepted time gap, initiation time and crossing were not effectively trained. The effects of training were maintained at follow-up for missed crossing opportunities only. There was preliminary evidence of potential efficacy of training for specific pedestrian safety behaviours, however, the long-term efficacy of training was not promising. Theory-driven research is needed to better understand why some behaviours are more trainable than others. More research is also needed to determine the real-world generalisability if training is to be recommended for older adult pedestrians.

A binary acceleration signal reduces overestimation in pedestrians' visual time-to-collision estimation for accelerating vehicles

When a pedestrian intends to cross the street, it is essential for safe mobility to correctly estimate the arrival time (time-to-collision, TTC) of an approaching vehicle. However, visual perception of acceleration is rather imprecise. Previous studies consistently showed that humans (mostly) disregard acceleration, but judge the TTC for an object as if it were traveling at constant speed (first-order estimation), which is associated with overestimated TTCs for positively accelerating objects. In a traffic context, such TTC overestimation could motivate pedestrians to cross in front of an approaching vehicle, although the time remaining is not sufficiently long. Can a simple acceleration signal help improve visual TTC estimation for accelerating objects? The present study investigated whether a signal that only indicates whether a vehicle is accelerating or not can remove the first-order pattern of overestimated TTCs. In a virtual reality simulation, 26 participants estimated the TTC of vehicles that approached with constant velocity or accelerated, from the perspective of a pedestrian at the curb. In half of the experimental blocks, a light band on the windshield illuminated whenever the vehicle accelerated but remained deactivated when the vehicle travelled at a constant speed. In the other blocks, the light band never illuminated, regardless of whether or not the vehicle accelerated. Participants were informed about the light band function in each block. Without acceleration signal, the estimated TTCs for the accelerating vehicles were consistent with an erroneous first-order approximation. In blocks with acceleration signal, participants substantially changed their estimation strategy, so that TTC overestimations for accelerating vehicles were reduced. Our data suggest that a binary acceleration signal helps pedestrians to effectively reduce the TTC overestimation for accelerating vehicles and could therefore increase pedestrian safety.

Camera-Monitor Systems as An Opportunity to Compensate for Perceptual Errors in Time-to-Contact Estimations

For the safety of road traffic, it is crucial to accurately estimate the time it will take for a moving object to reach a specific location (time-to-contact estimation, TTC). Observers make more or less accurate TTC estimates of objects of average size that are moving at constant speeds. However, they make perceptual errors when judging objects which accelerate or which are unusually large or small. In the former case, for instance, when asked to extrapolate the motion of an accelerating object, observers tend to assume that the object continues to move with the speed it had before it went out of sight. In the latter case, the TTC of large objects is underestimated, whereas the TTC of small objects is overestimated, as if physical size is confounded with retinal size (the size-arrival effect). In normal viewing, these perceptual errors cannot be helped, but camera-monitor systems offer the unique opportunity to exploit the size-arrival effect to cancel out errors induced by the failure to respond to acceleration. To explore whether such error cancellation can work in principle, we conducted two experiments using a prediction-motion paradigm in which the size of the approaching vehicle was manipulated. The results demonstrate that altering the vehicle's size had the expected influence on the TTC estimation. This finding has practical implications for the implementation of camera-monitor systems.