Effectiveness of Lateral Auditory Collision Warnings: Should Warnings Be Toward Danger or Toward Safety?

Abstract

Objective The present study investigated the design of spatially oriented auditory collision-warning signals to facilitate drivers’ responses to potential collisions. Background Prior studies on collision warnings have mostly focused on manual driving. It is necessary to examine the design of collision warnings for safe takeover actions in semi-autonomous driving. Method In a video-based semi-autonomous driving scenario, participants responded to pedestrians walking across the road, with a warning tone presented in either the avoidance direction or the collision direction. The time interval between the warning tone and the potential collision was also manipulated. In Experiment 1, pedestrians always started walking from one side of the road to the other side. In Experiment 2, pedestrians appeared in the middle of the road and walked toward either side of the road. Results In Experiment 1, drivers reacted to the pedestrian faster with collision-direction warnings than with avoidance-direction warnings. In Experiment 2, the difference between the two warning directions became nonsignificant. In both experiments, shorter time intervals to potential collisions resulted in faster reactions but did not influence the effect of warning direction. Conclusion The collision-direction warnings were advantageous over the avoidance-direction warnings only when they occurred at the same lateral location as the pedestrian, indicating that this advantage was due to the capture of attention by the auditory warning signals. Application The present results indicate that drivers would benefit most when warnings occur at the side of potential collision objects rather than the direction of a desirable action during semi-autonomous driving.

Ipsilateral and contralateral warnings: effects on decision-making and eye movements in near-collision scenarios

“…Nonetheless, ipsilateral warnings led to higher self-reported satisfaction than contralateral warnings. Previous research has found faster response times for ipsilateral warnings [23] (see [24] for vibrotactile warnings) than for contralateral warnings, or vice versa [18,26] or has suggested that time budget is a crucial moderator variable [25]. Our null result can be interpreted in the context of previous papers that have indicated that the phenomenon of spatial multisensory synergy is highly task-dependent [9].…”

“…When a warning is provided early, on the other hand, a contralateral warning will lead to a faster response because it attracts visual attention towards the hazard (see also [18]). More recently, Chen et al [26] investigated spatial pedestrian collision warnings for time budgets between 2 and 4 s and found that participants responded faster to contralateral than ipsilateral warnings for all time budgets. No advantage of ipsilateral warnings was found for short time budgets, which is inconsistent with Straughn et al's findings.…”

“…Several studies indicate that in driving, the effects of ipsilateral versus contralateral warnings are opposite from basic studies. That is, in driving, contralateral warnings have been claimed to be more effective than ipsilateral ones [18,26]. However, whether the beneficial effects of contralateral warnings become manifest may depend on whether there is enough time for the driver to visually detect the hazard [25].…”

“…The optimal number of trials to use is a dilemma in this type of research. On the one hand, it may be argued that our number of trials is small relative to typical psychophysics research [50] (see also [26], for a study with 120 trials per participant for evaluating directional warnings in a driving scenario). On the other hand, it may be argued that our number of trials is too large because near-collisions in real vehicles are rare events.…”

Road geometrical design out of standards: a preliminary study in a simulated context

“…Compared to this undeniable subjectivity, even though duly quali ed, there is the need of applying analytical procedures for quantifying the users' performance, in real conditions representing the analysed scenario, often not predictable by road standards. In the recent past, with the progress of vehicle on board sensors, the estimation of the driving behaviour performance was entrusted to some indices able to synthetize the performance on a homogeneous element of the road that, preferably, was the horizontal curve (Chen et al, 2022;He & Donmez, 2022). At this regard, one of the most used variables in the scienti c research was the Lateral Position (LP), as the trajectory in curve directly in uences the values of the lateral acceleration and steering and, in turn, the manoeuvre safety.…”