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Differential Effects of Focal and Ambient Visual Processing Demands on Driving Performance
Get PDFIn this study, the differential effects of focal and ambient visual demand on driving were investigated. Subjects participated in a dual-task experiment in which they performed a driving simulation task and a focal or ambient side-task. It was predicted that the focal side-task would cause a significant deterioration in the maintenance of longitudinal control but not lateral control, while there should be no effects of the ambient side-task on driving performance. In general, the results suggest a differentiation in the processing demands of focal and ambient vision
Differences in Simulated Car Following Behavior of Younger and Older Drivers
Get PDFOlder drivers are at risk for vehicle crashes due to impairments of visual processing and attention, placing these drivers at greater risk in driving tasks that require continuous attention to neighboring traffic, especially lead vehicles (LVs). We investigated car following behavior in 42 younger drivers (ages 18 to 44 years) and 58 older drivers (ages 65 to 86 years) in a driving simulator. The drivers were instructed to maintain two car lengths from a virtual LV. The LV varied its velocity according to a sum of three sine waves, making the velocity changes unpredictable to the drivers. A Fourier analysis was performed using the vehicle trajectory data to derive measures of coherence, gain, and delay as indices of car following behavior. These measures as well as headway distance were compared between the two groups. Older drivers were less able to match changes in the LV velocity indicated by lower coherence (0.76 v. 0.84, p=0.019) and larger gain (2.24 v. 1.74, p=0.031). However, these drivers followed further behind the LV than younger drivers, a potential compensatory strategy that may reduce collision risk for older drivers
The Perception of Optical Flow in Driving Simulators
Get PDFOptical flow is generated when a driver’s vehicle traverses a 3-D virtual environment in a driving simulator. Understanding the generated optical flow may help in lessening simulator sickness. Two experiments were designed to investigate the perceived optical flow in different driving environments using two driving simulators: 1) a fixed base simulator and 2) a turning cabin simulator whose turning cabin rotates around the y-axis. In the first experiment, the perception of optical flow when making left/right turns was studied using both simulators. Results revealed that subjects experienced a higher amount of optical flow when making right turns then left turns. In addition, the optical flow perceived by drivers in the fixed base simulator was greater than that in the turning cabin simulator. We designed the second experiment to investigate the optical flow perceived when driving straight ahead, driving on circular curves, and driving on curves with transitions (clothoids). Again, two simulators were used. The amount of optical flow was highest when driving on circular curves, and was lowest when driving straight ahead. While using the turning cabin simulator, the degree of optical flow decreased greatly on circular curves, and curves with clothoids as compared to that in the fixed base simulator. We conclude that optical flow in driving simulators can be lessen by using a turning cabin simulator
Three Navigation Systems With Three Tasks: Using the Lane-Change Test (LCT) to Assess Distraction Demand
Get PDFThe Lane Change Test (ISO, 2008; Mattes, 2003) was used to assess distraction demand when drivers completed three typical navigation tasks (an easy navigation task, a point of interest task and a difficult navigation task) using three different navigation systems. In order for the LCT to be a useful procedure, it must distinguish good from poor navigation systems and acceptable from unacceptable tasks performed using those systems. The results provide some general support for the LCT as a sensitive measure of distraction. Some aspects of the results, however, called into question the adequacy of the LCT as a sufficient measure of distraction. In particular, the LCT was found to be insensitive to task demands arising from excessive task duration. Since risk exposure is a function of secondary task duration (as well as other factors such as intensity, frequency and timing), it is recommended that a measure of task duration be incorporated in the LCT procedure. When the MDEV was modified to incorporate task duration, the resulting measure (mean deviation per average task) reflected more adequately the interaction demands of the various navigation tasks
How Do Drivers Behave in a Highly Automated Car?
Get PDFThis paper outlines the results of a driving simulator study conducted for the European CityMobil project, which was designed to investigate the effect of a highly automated driving scenario on driver behaviour. Drivers’ response to a number of ‘critical’ scenarios was compared in manual driving with that in automated driving. Drivers were in full control of the vehicle and its manoeuvres in the manual driving condition, whilst control of the vehicle was transferred to an ‘automated system’ in the automated driving condition. Automated driving involved the engagement of lateral and longitudinal controllers, which kept the vehicle in the centre of the lane and at a speed of 40 mph, respectively. Drivers were required to regain control of the driving task if the automated system was unable to handle a critical situation. An auditory alarm forewarned drivers of an imminent collision in such critical situations. Drivers’ response to all critical events was found to be much later in the automated driving condition, compared to manual driving. This is thought to be because drivers’ situation awareness was reduced during automated driving, with response only produced after drivers heard the alarm. Alternatively, drivers may have relied too heavily on the system, waiting for the auditory alarm before responding in a critical situation. These results suggest that action must be taken when implementing fully automated driving to ensure that the driver is kept in the loop at all times and is able to respond in time and appropriately during critical situations
Acquisition, Response, and Error Rates With Three Suites of Collision Warning Sounds
Get PDFThe acquisition, response speed, and error rates of three suites of collision warning sounds were investigated to evaluate the effect of sound alteration on responding. In each suite, four sounds were pictorially associated with four collision scenarios. Suite A included two natural sounds, and two artificial sounds semantically associated with one of four crash scenarios; Suite B was a variant of A, altered to reduce perceived urgency; Suite C was a set of abstract sounds constructed to vary in urgency and matched to the subjective urgency of each scenario. For each suite, subjects first learned to associate the suite’s warning sounds with an assigned crash scenario to an established criterion. This was followed by reaction time trials in which a sound was played and subjects quickly identified the scenario associated with the sound. For both young and old subjects, Suite A produced the shortest reaction times and fewest trials to criterion, suggestive of the response efficiencies reported for auditory icons. In contrast, the sounds used in Suite B, while variants of Suite A, were most difficult to learn and were not different from Suite C with respect to error rates and reaction time. It is suggested that even relatively minor alterations of a warning sound can result in marked differences in acquisition and performance
Crash Risk: Eye Movement as Indices for Dual Task Driving Workload
Get PDFThe goal of the present study was to examine eye movements as a function of dual task difficulty while driving. Two tasks were examined: maintaining a predetermined distance while car following and detecting a light change. Task demands were manipulated by varying the amplitude of lead vehicle’s (LV) speed change and increasing the average LV speed. As task demands increased, the number of saccades decreased. There was no significant difference in number of fixations, fixation duration, number of eye blinks, or pupil size. While car following performance did not change, drivers were more accurate at the light detection task at the 100% amplitude condition verses the 120
Curve Negotiation: Identifying Driver Behavior Around Curves with the Driver Performance Database
Get PDFApproximately one quarter of all accidents outside city limits occur while driving around curves, where assistance systems could prevent the driver from negotiating curves with excessive speed. This study argues that the parameterizing of a Driving Assistant System could be realized with data from realistic, noncritical driving behavior offered by Naturalistic Driving Studies. The Driver Performance Database presented in this study provides a tool for observing normal, noncritical driving behavior. The Database contains results from road tests with an instrumented vehicle that were carried out on public road traffic on a predetermined route, which was precisely measured in advance. In addition to vehicle state parameters, we also collected data concerning the driving environment and physiological information. With the Driver Performance Database it is possible to generate different facets of human driving behavior in a descriptive and normative way, which is illustrated by driver behavior in curve negotiation
The Adaption Test: The Development of a Method to Measure Speed Adaption to Traffic Complexity
No full textTo monitor novice driver performance in the first years of solo driving, a test aimed at assessing speed adaptation to the traffic situation was developed and evaluated. The Adaptation Test consisted of 18 traffic scenes presented in two (almost) identical photographs, which differed in one single detail, increasing the situation’s complexity. The difference in reported speed between the two pictures was used as an indication of drivers’ adaptation of speed to the complexity of the traffic situation. A previous study showed that novice, unsafe and overconfident drivers, as identified in an on-road driving assessment, performed worse on the Adaptation Test (i.e. less often reported a lower speed in the more complex situation). The analysis of new data in this paper shows no correlation between performance on the Adaptation Test and self-reported crashes, and that after two years, experienced drivers had improved their performance on the Adaptation Test just as much as novice drivers
Effects of Cognitive and Physical Decline on Older Drivers' Side-to-Side Scanning for Hazards While Executing Turns
Get PDFAge related declines in cognitive and physical ability significantly impair an older adult’s ability to safely drive. As we age it gradually becomes more difficult to scan for, detect, process, and ultimately react to critical elements in our driving environment. Older drivers are over represented in angled impacts in intersections. Research has shown that older drivers tend to execute fewer side-to-side glances while in the process of turning than middle-aged drivers. This decrease in scanning can directly lead to an increase in angled impacts. The present research investigates the correlation between cognitive and physical decline and the likelihood that an older driver will execute side-to-side glances at the beginning and during a turn. Results of both simulator and field drive sessions with fifty-four older drivers 70-89 years of age demonstrated that cognitive, but not physical, decline was significantly correlated with a decrease in side-to-side scanning while turning