Age, cognitive load, and multimodal effects on driver response to directional warning

Using the center of gravity to help blind people measure water levels in bottles

People who are blind struggle to gauge water levels in bottles by weight alone. This work shows that combining information about a filled bottle's weight and center of gravity can enhance the accuracy of measuring the water level. Bumps were attached to the sides of cylindrical bottles at positions corresponding to the centers of gravity of water levels between 4 and 9. These bumps allow individuals to use additional information about the center of gravity to measure the water level in the bottle. Eight subjects who were blind participated in the experiment, and the results indicated that using the center of gravity method with a plastic bottle was the most accurate, with an average water level error of 0.04, but it took 57.83 seconds. Contrarily, using the weight method, the plastic bottle yielded the fastest results, with an average time of 6.51 seconds, but it led to an average water level error of 0.88.

Hazard warning modalities and timing thresholds for older drivers with impaired vision

PURPOSE

We examined collision warning systems with different modalities and timing thresholds, assessing their impact on responses to pedestrian hazards by drivers with impaired contrast sensitivity (ICS).

METHODS

Seventeen ICS (70-84 y, median CS 1.35 log units) and 17 normal vision (NV: 68-73 y, median CS 1.95) participants completed 6 city drives in a simulator with 3 bimodal warnings: visual-auditory, visual-directional-tactile, and visual-non-directional-tactile. Each modality had one drive with early and one with late warnings, triggered at 3.5 s and 2 s time-to-collision, respectively.

RESULTS

ICS participants triggered more early (43 vs 37 %) and late warnings (12 vs 6 %) than NV participants and had more collisions (3 vs 0 %). Early warnings reduced time to fixate hazards (late 1.9 vs early 1.2 s, p < 0.001), brake response times (2.8 vs 1.8 s, p < 0.001) and collision rates (1.2 vs 0.02 %). With late warnings, ICS participants took 0.7 s longer to brake than NV (p < 0.001) and had an 11 % collision rate (vs 0.7 % with early warnings). Non-directional-tactile warnings yielded the lowest collision rates for ICS participants (4 vs auditory 12 vs directional-tactile 15.2 %) in late warning scenarios. All ICS participants preferred early warnings.

CONCLUSIONS

While early warnings improved hazard responses and reduced collisions for ICS participants, late warnings did not, resulting in high collision rates. In contrast, both early and late warnings were helpful for NV drivers. Non-directional-tactile warnings were the most effective in reducing collisions. The findings provide insights relevant to the development of hazard warnings tailored for drivers with impaired vision.

Effects of whole-body vibration on driver drowsiness: A review

INTRODUCTION

Whole-body vibration has direct impacts on driver vigilance by increasing physical and cognitive stress on the driver, which leads to drowsiness, fatigue and road traffic accidents. Although sleep deprivation, sleep apnoea and alcohol consumption can also lead to driver drowsiness, exposure to steady vibration is the factor most readily controlled by changes to vehicle design, yet it has received comparatively less attention.

METHODS

This review investigated interrelationships between the various components of whole-body vibration and the physiological and cognitive parameters that lead to driver drowsiness, as well as the effects of vibration parameters (frequency, amplitude, waveform and duration). Vibrations transmitted to the driver body from the vehicle floor and/or seat have been considered for this review, whereas hand-arm vibration, shocks, acute or transient vibration were excluded from consideration.

RESULTS

Drowsiness is affected by interactions between the frequency, amplitude, waveform and duration of the vibration. Under optimal conditions, whole-body vibration can induce significant drowsiness within 30 min. Low frequency whole-body vibrations, particularly vibrations of 4-10 Hz, are most effective at inducing drowsiness. This review notes some limitations of current studies and suggests directions for future research.

CONCLUSIONS

This review demonstrated a strong causal link exists between whole-body vibration and driver drowsiness. Since driver drowsiness has been established to be a significant contributor to motor vehicle accidents, research is needed to identify ways to minimise the components of whole-body vibration that contribute to drowsiness, as well as devising more effective ways to counteract drowsiness.

PRACTICAL APPLICATIONS

By raising awareness of the vibrational factors that contribute to drowsiness, manufacturers will be prompted to design vehicles that reduce the influence of these factors.

Do Congruent Auditory Stimuli Facilitate Visual Search in Dynamic Environments? An Experimental Study Based on Multisensory Interaction

The purpose of this study was to investigate the cue congruency effect of auditory stimuli during visual search in dynamic environments. Twenty-eight participants were recruited to conduct a visual search experiment. The experiment applied auditory stimuli to understand whether they could facilitate visual search in different types of background. Additionally, target location and target orientation were manipulated to clarify their influences on visual search. Target location was related to horizontal visual search and target orientation was associated with visual search for an inverted target. The results regarding dynamic backgrounds reported that target-congruent auditory stimuli could speed up the visual search time. In addition, the cue congruency effect of auditory stimuli was critical for the center of the visual display but declined for the edge, indicating the inhibition of horizontal visual search behavior. Moreover, few improvements accompanying auditory stimuli were provided for the visual detection of non-inverted and inverted targets. The findings of this study suggested developing multisensory interaction with head-mounted displays, such as augmented reality glasses, in real life.

Effect of mapping characteristic on audiovisual warning: Evidence from a simulated driving study

Advanced driver assistance systems (ADAS) can enhance road safety by sending warning signals to drivers. Multimodal signals are gaining attention in ADAS warning design because they offer redundant information that facilitates human-system communication. However, no consensus has been reached on which multimodal design offers optimal benefit to road safety. Icons iconically map the real world and are associated with fast recognition and response time. Therefore, this study aims to investigate whether visual and auditory icons will benefit the effectiveness of audiovisual multimodal warnings. Thirty-two participants (16 females) experienced four types of unimodal warnings (high and low mapping visual warnings and high and low mapping auditory warnings) and four types of audiovisual warnings (high mapping visual + high mapping auditory warning, low mapping visual + low mapping auditory warning, high mapping visual + low mapping auditory warning, and low mapping visual + high mapping auditory warning) in simulated driving conditions. Visual warnings are presented in a head-up display. Results showed that multimodal warnings outperformed unimodal warnings (i.e., modality effect). We found mapping effect in audiovisual warnings, but only high mapping auditory constituents benefited warning effectiveness. Eye movement results revealed that the high mapping constituents might distract drivers from the road. This study adds evidence that multimodal warnings can offer extra benefits to drivers and high mapping auditory signals should be included in multimodal warning design to achieve better driving performance.

The effects of age and physical exercise on multimodal signal responses: Implications for semi-autonomous vehicle takeover requests

The present study examined whether the non-chronological age factor, engagement in physical exercise, affected responses to multimodal (combinations of visual, auditory, and/or tactile) signals differently between younger and older adults in complex environments. Forty-eight younger and older adults were divided into exercise and non-exercise groups, and rode in a simulated Level 3 autonomous vehicle under four different task conditions (baseline, video watching, headway estimation, and video-headway combination), while being asked to respond to various multimodal warning signals. Overall, bi- and trimodal warnings had faster response times for both age groups across driving conditions, but was more pronounced for older adults. Engagement in physical exercise was associated with smaller maximum braking force for younger participants only, and also corresponded to longer average fixation durations, compared to the non-exercise group. Findings from this research can help to guide decisions about the design of warning and information systems for semi-autonomous vehicles.

Vibration warning design for reaction time reduction under the environment of intelligent connected vehicles

Scenario-based warnings for road safety can be provided in the environment of intelligent connected vehicles via Bluetooth earphones or smart wristbands; designing an optimal means of presentation to drivers is an important point of consideration. Vibration warnings have been widely studied owing to their unique benefits. This experimental study aims to identify suitable body parts for vibration warnings during driving. The independent variables were the vibration position (three levels of stimulus, i.e., wrist, shin, and upper jaw) and response effector (two levels, i.e., hand and foot). Experiment Tasks 1 and 2 measured participants' simple reaction time and choice reaction time, respectively, when providing vibration warnings in non-driving situations. The results demonstrate that the vibration on the upper jaw has the shortest simple reaction time and choice reaction time. The effect of stimulus-response consistency on choice reaction time was insignificant. Task 3 was similar to Task 2, with the exception of simulated driving. Compared to the result in Task 2, the choice reaction time in Task 3 was approximately 200 ms longer. Vibration of the upper jaw was reported to have the highest perceived intensity and preference. Based on the study results, the design implications for wearable vibration warnings of collision avoidance systems are presented.

A Few Critical Human Factors for Developing Sustainable Autonomous Driving Technology

The purpose of this study is to develop a framework that can identify critical human factors (HFs) that can generate human errors and, consequently, accidents in autonomous driving level 3 situations. Although much emphasis has been placed on developing hardware and software components for self-driving cars, interactions between a human driver and an autonomous car have not been examined. Because user acceptance and trust are substantial for the further and sustainable development of autonomous driving technology, considering factors that will influence user satisfaction is crucial. As autonomous driving is a new field of research, the literature review in other established fields was performed to draw out these probable HFs. Herein, interrelationship matrices were deployed to identify critical HFs and analyze the associations between these HFs and their impact on performance. Age, focus, multitasking capabilities, intelligence, and learning speed are selected as the most critical HFs in autonomous driving technology. Considering these factors in designing interactions between drivers and automated driving systems will enhance users’ acceptance of the technology and its sustainability by securing good usability and user experiences.