Quantifying the Subjective Brightness of Retroreflective Material Using Magnitude Estimations

Ten small patches of retroreflective material were evaluated using a method of magnitude estimation to quantify the effect of changing the coefficient of retroreflection (RA) on brightness perception. Seventeen undergraduates participated. The results show that brightness is tightly linked with RA. Brightness was influenced more by changes in lower RA than changes in higher RA and follows Steven’s power law for brightness. Practical and theoretical implications are discusse

Simulator Sickness Questionnaire: Twenty Years Later

The present study used simulator sickness questionnaire data from nine different studies to validate and explore the work of the most widely used simulator sickness index. The ability to predict participant dropouts as a result of simulator sickness symptoms was also evaluated. Overall, participants experiencing nausea and nausea-related symptoms were the most likely to fail to complete simulations. Further, simulation specific factors that increase the discrepancy between visual and vestibular perceptions are also related to higher participant study dropout rates. As a result, it is suggested that simulations minimize turns, curves, stops, et cetera, if possible, in order to minimize participant simulation sickness symptoms. The present study highlights several factors to attend to in order to minimize elevated participant simulation sickness

Lane Line Markings in Advance of Lane-Reduction Transitions

DTFH61-13-D-00024Roadway lane-reduction transitions have long been reported to be problematic to drivers. Whether this problem is the result of a lack of understanding of lane-reduction signing or lane markings, a simple failure to comply with such markings, or other unidentified factors is unknown. This study, completed in 2016, explored driver comprehension of six different lane-reduction markings. The markings varied in terms of the incorporation and length of dotted and broken lines. In addition, half of the markings included a solid white line adjacent to the dotted/broken line. The supplemental solid white line resulted in improved understanding that the rightmost lane would end, earlier reported lane changes, and the highest preference ratings. Dotted lines also resulted in better understanding of an upcoming necessary lane change than did the longer, more traditional broken lane lines. This study contains recommendations and suggestions for lane-reduction marking changes to the Manual on Uniform Traffic Control Devices

Preferred Following Distance and Performance in an Emergency Event while Using Cooperative Adaptive Cruise Control

This study explored human factors issues associated with cooperative adaptive cruise control (CACC); specifically the relationship between drivers’ preferred following distance, assigned following distance, and driving performance. Participants drove in a dedicated lane and experienced a vehicle merging in front of their vehicle and later, an emergency event that required intervention in order to avoid a collision. Drivers followed at either a near or a far distance. Drivers’ perceived workload did not vary between the cruise and postmerge periods. However, workload was significantly greater after the emergency crash event. Workload did not vary significantly based on following distance assignment or preference. Those participants assigned to the near following distance were more likely to hover their foot over the brake during the merging event and to react faster to the emergency event. As with workload, performance (collision avoidance) did not vary significantly due to following distance assignment or preference. In other words, one’s abilities may not necessarily reflect their following preferences. This is a promising finding for widespread implementation of CACC

Projection Displays Induce Less Simulator Sickness than Head-Mounted Displays in a Real Vehicle Driving Simulator

Driving simulators are necessary for evaluating automotive technology for human users. While they can vary in terms of their fidelity, it is essential that users experience minimal simulator sickness and high presence in them. In this paper, we present two experiments that investigate how a virtual driving simulation system could be visually presented within a real vehicle, which moves on a test track but displays a virtual environment. Specifically, we contrasted display presentation of the simulation using either head-mounted displays (HMDs) or fixed displays in the vehicle itself. Overall, we find that fixed displays induced less simulator sickness than HMDs. Neither HMDs or fixed displays induced a stronger presence in our implementation, even when the field-of-view of the fixed display was extended. We discuss the implications of this, particular in the context of scenarios that could induce considerable motion sickness, such as testing non-driving activities in automated vehicles