Comparison of Driver Brake Reaction Times to Multimodal Rear-end Collision Warnings

This study examined the effectiveness of rear-end collision warnings presented in different sensory modalities as a function of warning timing in a driving simulator. Drivers experienced four warning conditions: no warning, visual, auditory, and tactile. The warnings activated when the time-to-collision (TTC) reached a critical value of 3.0 or 5.0 s TTC. Driver reaction time (RT) was captured from the time the driver crossed the warning activation threshold to brake initiation. Mean driver RT data showed that the tactile warning significantly outperformed the visual warning, providing support for tactile displays as effective rear-end collision warnings

Evaluating Multimodal Driver Displays of Varying Urgency

Previous studies have evaluated Audio, Visual and Tactile warnings for drivers, highlighting the importance of conveying the appropriate level of urgency through the signals. However, these modalities have never been combined exhaustively with different urgency levels and tested while using a driving simulator. This paper describes two experiments investigating all multimodal combinations of such warnings along three different levels of designed urgency. The warnings were first evaluated in terms of perceived urgency and perceived annoyance in the context of a driving simulator. The results showed that the perceived urgency matched the designed urgency of the warnings. More urgent warnings were also rated as more annoying but the effect of annoyance was lower compared to urgency. The warnings were then tested for recognition time when presented during a simulated driving task. It was found that warnings of high urgency induced quicker and more accurate responses than warnings of medium and of low urgency. In both studies, the number of modalities used in warnings (one, two or three) affected both subjective and objective responses. More modalities led to higher ratings of urgency and annoyance, with annoyance having a lower effect compared to urgency. More modalities also led to quicker responses. These results provide implications for multimodal warning design and reveal how modalities and modality combinations can influence participant responses during a simulated driving task

Warning a Distracted Driver: Smart Phone Applications, Informative Warnings and Automated Driving Take-Over Requests

abstract: While various collision warning studies in driving have been conducted, only a handful of studies have investigated the effectiveness of warnings with a distracted driver. Across four experiments, the present study aimed to understand the apparent gap in the literature of distracted drivers and warning effectiveness, specifically by studying various warnings presented to drivers while they were operating a smart phone. Experiment One attempted to understand which smart phone tasks, (text vs image) or (self-paced vs other-paced) are the most distracting to a driver. Experiment Two compared the effectiveness of different smartphone based applications (app’s) for mitigating driver distraction. Experiment Three investigated the effects of informative auditory and tactile warnings which were designed to convey directional information to a distracted driver (moving towards or away). Lastly, Experiment Four extended the research into the area of autonomous driving by investigating the effectiveness of different auditory take-over request signals. Novel to both Experiment Three and Four was that the warnings were delivered from the source of the distraction (i.e., by either the sound triggered at the smart phone location or through a vibration given on the wrist of the hand holding the smart phone). This warning placement was an attempt to break the driver’s attentional focus on their smart phone and understand how to best re-orient the driver in order to improve the driver’s situational awareness (SA). The overall goal was to explore these novel methods of improved SA so drivers may more quickly and appropriately respond to a critical event.Dissertation/ThesisDoctoral Dissertation Applied Psychology 201

Forward collision warning modality and content: a summary of human factors studies

The report summarizes a nonexhaustive sample of 17 studies covering 27 experiments on human factors and forward-collision warnings. Subject samples ranged from 11 to 260 (median=30). Twenty-three experiments were conducted using driving simulators; 4 were on test tracks. Typically subjects followed a lead vehicle that braked abruptly, triggering audio, visual, tactile, or combined warnings. Response/reaction time was reported as a dependent measure in 18 of the 27 experiments, the number of crashes in 8, distance headway (gap) in 3, perceived urgency in 7 (both by the same authors), perceived annoyance in 11, and probability of warning recall in 1. Providing a warning leads to a more desired outcome. Response/reaction times were briefer in 9 of the 9 studies that considered this and all 4 of the studies that examined crashes reported fewer crashes with warnings. Warnings 4 to 10 dB above the background level led to the best performance, but only one study systematically varied warning intensity. Of the combinations explored, multimodal warnings tended to lead to better performance than unimodal warnings, though none of them considered seat-belt-pretensioner activation, an effective way to reduce crash injuries. Studies could be improved by the use of consistent crash scenarios, defined measures, predictions of performance, and including older drivers in test samples.Nissan Technical Center North Americahttp://deepblue.lib.umich.edu/bitstream/2027.42/134038/1/103247.pdf-1Description of 103247.pdf : Final repor

Dynamic vibrotactile signals for forward collision avoidance warning systems

OBJECTIVE: Four experiments were conducted in order to assess the effectiveness of dynamic vibrotactile collision-warning signals in potentially enhancing safe driving. BACKGROUND: Auditory neuroscience research has demonstrated that auditory signals that move toward a person are more salient than those that move away. If this looming effect were found to extend to the tactile modality, then it could be utilized in the context of in-car warning signal design. METHOD: The effectiveness of various vibrotactile warning signals was assessed using a simulated car-following task. The vibrotactile warning signals consisted of dynamic toward-/away-from-torso cues (Experiment 1), dynamic versus static vibrotactile cues (Experiment 2), looming-intensity- and constant-intensity-toward-torso cues (Experiment 3), and static cues presented on the hands or on the waist, having either a low or high vibration intensity (Experiment 4). RESULTS: Braking reaction times (BRTs) were significantly faster for toward-torso as compared to away-from-torso cues (Experiments 1 and 2) and static cues (Experiment 2). This difference could not have been attributed to differential responses to signals delivered to different body parts (i.e., the waist vs. hands; Experiment 4). Embedding a looming-intensity signal into the toward-torso signal did not result in any additional BRT benefits (Experiment 3). CONCLUSION: Dynamic vibrotactile cues that feel as though they are approaching the torso can be used to communicate information concerning external events, resulting in a significantly faster reaction time to potential collisions. APPLICATION: Dynamic vibrotactile warning signals that move toward the body offer great potential for the design of future in-car collision-warning system

Informative Collision Warnings: Effect of Modality and Driver Age

Research has revealed that when drivers are presented with an informative tactile collision warning, they are able to produce faster braking reaction times (BRTs) which may potentially reduce the likelihood and severity of rear-end collisions. To expand on this research, we investigated the effectiveness of unimodal (tactile) and multisensory (audiotactile) informative collision warnings for younger and older drivers. In line with our previous results, driver BRTs were significantly faster when they were presented with an informative signal as compared to a non-informative signal and a control condition in which no warnings were presented. The results also revealed that the unimodal informative warning was just as effective as the multisensory warning. Intriguingly, older drivers exhibited faster BRTs than younger drivers, and were significantly faster following the presentation of multisensory warning signals. Finally, this study identifies the need to compare new configurations of informative tactile collision warning signals

Effects of Visibility and Alarm Modality on Workload, Trust in Automation, Situation Awareness, and Driver Performance

Driving demands sustained driver attention. This attentional demand increases with decreasing field visibility. In the past researchers have explored and investigated how collision avoidance warning systems (CAWS) help improve driving performance. The goal of the present study is to determine whether auditory or tactile CAWS have a greater effect on driver performance, perceived workload, system trust, and situation awareness (SA). Sixty-three undergraduate students from Old Dominion University participated in this study. Participants were asked to complete two simulated driving sessions along with Motion Sickness Susceptibility Questionnaire, Background Information Questionnaire, Trust Questionnaire, NASA Task Load Index Questionnaire, Situation Awareness Rating Technique Questionnaire, and Simulator Sickness Questionnaire. Analyses indicated that drivers in the tactile modality condition had low perceived workload. Drivers in the heavy fog visibility condition had the highest number of collisions and red-light tickets. Drivers in the heavy fog condition also reported having the highest overall situation awareness. Drivers in the clear visibility condition trusted tactile alarms more than the auditory alarms, whereas drivers in the heavy fog condition trusted auditory alarms more than tactile alarms. The findings of this investigation could be applied to improve the design of CAWS that would help improve driver performance and increase safety on the roadways

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

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 take-over 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 non-significant. 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

How drivers respond to visual vs. auditory information in advisory traffic information systems

To date, many efforts have been made to explore how to support driver\u27s decision-making process with advisory information. Previous studies mainly focus on a single modality, e.g. the visual, auditory or haptic modality. In contrast, this study compares data from two simulator studies with 50 participants in total, where the visual vs. the auditory modality was used to present the same type of advisory traffic information under the same driving scenarios. Hereby we compare the effect of these two modalities on drivers\u27 responses and driving performance. Our findings indicate that modality influences the drivers\u27 behaviour patterns significantly. Visual information helps drivers to drive more accurately and efficiently, whereas auditory information supports quicker responses. This suggests that there are potential benefits in applying both modalities in tandem, as they complement each other. Correspondingly, we present several design recommendations on Advisory Traffic Information Systems

Effectiveness of Tactile Warning and Voice Command for Enhancing Safety of Drivers

Safety is impaired when drivers are required to perform main driving task (tracking of own car, distance maintenance between own car and a leading car, and response to target objects) and secondary task simultaneously, for example, responding to target cars on the road while operating in-vehicle equipment. A two-factor (presence or absence of tactile warning by input modality (no secondary task, voice command for a secondary task, and manual input for a secondary task)) within-subject design of ten licensed males was used to investigate how to compensate for safety impairments (decreased performance of a main and a secondary task such as increased tracking error during driving or increased reaction time to target cars on the road). We investigated whether the use of tactile warnings transmitted via left and right thighs for detecting road objects and voice command to operate in-vehicle equipment could compensate for safety impairments such as the increased reaction time to target cars on the road, the increase of detection error of target cars, or increased tracking error in driving. The accuracy and speed of responses to target cars encountered during driving were reduced when a driver was asked to perform the main and the secondary task simultaneously compared to situations performing only the main driving task (tracking, distance maintenance, and response to target cars). The availability of a tactile warning system for road objects compensated for these diminished performance measures, including slower response times and the increased detection error of target cars. Likewise, voice command contributed to enhanced performance of the main driving task such as decrease of tracking error