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Internal Distraction and Driving: Does It Show?
No full textThe effect of daydreaming (‘internal distraction’) on driving behavior little is known. Since it happens to some extent to most drivers, an explorative study was performed to see whether in an experimental setting something like daydreaming could occur, and if so whether this would show up in driving behavior. Three groups of participants made two drives in the TNO driving simulator. Group 1 did not perform any secondary task, Group 2 performed a ‘thinking and reasoning’ task (daydreaming condition) during specific parts of the drive, and Group 3 performed a ‘listening and remembering’ task during the same sections of the drives as Group 2. Mostly an effect was found for the ‘listening and remembering’ task. If an effect was found for the internal distraction condition, it indicated a same (negative) effect as the ‘listening and remembering’ task, although less severe
Comparison of Trained and Untrained Novice Drivers’ Gaze Behavior in Risky and Non-Risky Scenarios
Get PDFPC-based training programs have been developed that have been shown to improve novice drivers’ hazard anticipation skills. Such programs give novice drivers information about particular driving situations (scenarios) where hidden threats could appear. We wanted to know whether this improvement in trained novice drivers’ scanning skills was simply because the trained drivers were scanning more in general or, instead, were scanning more specifically in the scenarios in which potential threats could appear. In order to evaluate this question, we trained 11 novice drivers using a PC-based program and then compared their hazard anticipation performance on a driving simulator with the hazard anticipation performance of 11 untrained novice drivers. The drivers’ eye movements were recorded for the duration of the drives. The glances of the drivers to the right (the correct response in most of the risky scenarios) were analyzed for each of the relevant risky scenarios and for stretches of non-risky situations. The trained drivers did look to the right 6.5% more in the non-risky situations than did the untrained drivers, although the difference was far from significant. However, the trained drivers looked to the right 32.7% more in the risky scenarios than in the non-risky situations, indicating they were discriminating quite well between the two situations. The untrained drivers also showed a smaller, but significant, discrimination between the risky scenarios and non-risky situations, as they looked to the right 18.9% more in the risky scenarios than in the non-risky stretches
Observation of Gap Acceptance During Intersection Approach
Get PDFThis paper presents the results of a field test evaluating drivers’ decision making and gap acceptance for a left turn maneuver with opposite traffic; with a focus on the scenario where the turning vehicle is approaching the intersection. Twenty-three participants drove an instrumented vehicle ten times around an extended block turning left at four specific intersections. DGPS and radar data were combined to represent the trajectories of the turning vehicle and opposite traffic and to compute the gap between the turning vehicle and the lead vehicle of the on-coming traffic. The results cover the categorization of driver behavior based on the velocity profile while crossing the intersection. The velocity profile shows whether a driver stopped during the maneuver and the categories are defined based on where the driver stopped. The trajectories were then further sorted to account for the difference in speed profile or stopping location within one category. The characteristics of the accepted and rejected lags are presented and discussed, with an emphasis on turning drivers’ speed adaptation to the presence of an on-coming vehicle, and the presence of following traffic on a decision to stop. The conclusion of this study is that although valuable information was gathered during this field test, the data collection setup did not capture sufficiently the characteristic of the opposite traffic for a quantitative description of the effect of subsequent gaps on drivers’ decision to stop. Therefore, further data collection will be conducted on an instrumented intersection on a closed track
Simulator-Based Driving with Hemianopia: Detection Performance and Compensatory Behaviors on Approach to Intersections
No full textOBJECTIVES In 22 states people with homonymous hemianopia (complete loss of the visual field on the sameside in both eyes) are explicitly prohibited from driving, as they do not meet the minimum visualfield requirements for driver licensing. However, there is little scientific evidence derived eitherfrom on-road or driving simulator studies about the safety of driving with hemianopia. If the eyeand head were kept stationary, people with hemianopia would not detect anything on the side ofthe field loss. In the real world, however, they may be able to compensate for the loss byexploring the affected (blind) side using head- and eye-scanning. It has been reported that inHolland (where driving with hemianopia is permitted), driving examiners consider increasedhead-scanning (especially on approach to intersections) to be an effective compensation forperipheral visual field defects (Coeckelbergh et al., 2002). Whether increased head-scanningwhile driving results in better detection performance has never been quantitatively investigated.We conducted a simulator-based evaluation of driving with hemianopia to investigate detectionperformance and head movement behaviors on approach to intersections.METHODSTo date, eight people with complete homonymous hemianopia (5 left and 3 right), and withoutvisual neglect or significant cognitive decline have completed the study. All had current or recentdriving experience (within the last 6 years). They completed two simulator sessions, one weekapart, driving in a high-fidelity simulator. Each session consisted of a familiarization period of30-60 minutes followed by 6 test drives (each about 12 minutes in duration). The primarysimulator task was to detect and respond (by a horn press) to the appearance of pedestrian targetsin a variety of traffic situations while driving according to the normal rules of the road. Targetsappeared randomly in locations relevant to real-world driving. There were two types of targets:“roadway” targets, which appeared either on the left or right of the road at small (~ 4°) or large(~14°) eccentricities from the presumed line of sight, and “intersection” targets, which wereplaced near or at intersections to test whether drivers were scanning effectively whenapproaching an intersection. Primary outcome measures were the percentage of targets detectedand reaction times when detected. Head movements were recorded with an inexpensive, lightweight,head-mounted optical head tracking system. Preliminary analyses of head movementbehaviors were conducted for intersections with stop or yield signs. Based on visual inspectionof the head movement plots, the number and direction of head movements were recorded and head movement scanning was graded on a 4-point scale (from 1 inadequate to 4 excellent). Inaddition, we are developing methods to automatically quantify driving skills (e.g., steering, laneposition) from the simulator data output.RESULTSDetection rates for roadway pedestrian targets were lower and reaction times longer on the blindside than the seeing side (p ≤ 0.05). Blind side: median detection rate 47% (IQR 22 to 63%),median reaction time 1.65s (IQR 1.05 to 1.84s); seeing side: median detection rate 93% (IQR89% to 99%), median reaction time 0.93s, (IQR 0.88 to 1.25s). Detection rates on the blind sidewere lower at the larger eccentricity (median 23%) than the smaller eccentricity (median 66%; p= 0.01). Drivers with right hemianopia (RH) detected 83% of intersection pedestrian targets onthe extreme left of an intersection but none on the extreme right, whereas drivers with lefthemianopia (LH) detected 33% on the extreme left and 80% on the extreme right. Better headscanningscores were associated with better detection rates for intersection targets at extremepositions on the blind side (Spearman r = 0.79, p = 0.02). Two of the drivers with LH showedinadequate scanning (grade 1), failing to scan to the left at more than 60% of intersections. Therest of the drivers with LH and all three with RH demonstrated better head-scanning (grades 2-4)with some compensatory head movement behaviors. At T-intersections with no incoming roadon one side, they scanned more frequently in the direction of the “absent” road when it was onthe blind side (RH 40% and LH 80%) than when it was on the seeing side (RH and LH <10%).When there were incoming roads on both sides, the first head scan was normally to the left forLH, but it was to the right about 30% of the time for drivers with RH.CONCLUSIONSThese results provide evidence of widely varying levels of compensation and detection abilitiesamongst drivers with hemianopia, suggesting that fitness to drive should be evaluated on anindividual basis. The preliminary finding of a relationship between head-scanning score andintersection detection performance will be further evaluated using automated methods toquantify head movement behaviors and a larger sample of drivers with hemianopia. Furthermore,we will compare head movement behaviors of drivers with hemianopia to matched controldrivers without visual field loss.REFERENCESCoeckelbergh, T.R., Brouwer, W.H., Cornelissen, F.W., van Wolffelaar, P., Kooijman, A.C.(2002). The effect of visual field defects on driving performance: a driving simulator study. ArchOphthalmol, 120, 1509-1516
The Influence of Fog on Motion Discrimination Thresholds in Car Following
Get PDFA possible explanation for close following in fog is that it would allow drivers to control headway more precisely by reducing motion perception thresholds. The purpose of our experiments was to determine the motion discrimination thresholds for closing and receding under normal and foggy conditions. An experiment and a pilot study were conducted on a driving simulator in which subjects were presented with a car following situation. Subjects had to press a button as soon as they detected that the lead vehicle was closing or receding, and their choice response time was recorded. Several visibility conditions were tested corresponding to different contrasts between the lead vehicle outline and the background, ranging from clear weather conditions to foggy conditions in which the vehicle could only be seen by its rear lights. Initial headway and lead vehicle acceleration were also varied. As expected, response times were longest with small accelerations and long headways. There was also an effect of visibility conditions with longer response times when the contrast between the vehicle outline and the background was 5% or less. Moreover, the reduction of response time corresponding to a reduction of headway was greater in fog than in clear conditions, at least in the given range of distances. This suggests that driving closer in fog may have a perceptual-control benefit in terms of a reduction in response times that partially offsets the reduction in timeheadway. Driving closer may also benefit lateral trajectory control because the lead vehicle is less likely to be lost in fog
I-TSA Traffic Safety Assessment in a Simulator Experiment with Integrated Information and Assistance Systems
Get PDFThe increasing number and complexity of in-vehicle information systems (IVIS) and advanced driver assistance systems (ADAS) require an accurate and timely assessment of their impact on traffic safety even during the development process. The I-TSA evaluation tool, developed within the German research consortium INVENT, offers a standardized procedure for the assessment of traffic safety based on the driving error occurrence in up to 10 categories of parameters (e.g., the category “longitudinal control” includes the errors in speed, time headway and time to collision). The objective of the experiment presented here was to determine the validity and sensitivity of the I-TSA tool for this evaluation process. A homogeneous cohort of 41 young, healthy males (25 to 40 years old) drove for approximately 1 hour in a static simulator environment. The scenario on a two-lane motorway consisted of 4 counterbalanced drives with easy and difficult road shapes and traffic conditions. The trial included several interaction tasks with IVIS and ADAS differing in their stage of integration and adaptivity. The successful induction of high workload levels could be both detected by objective (such as speed compensation) and subjective measures (questionnaire). Highly significant differences in the safety levels were found between the easy and the difficult drives (demonstrating the suitability of the procedure) as well as between the sections with default and integrated behavior of the information systems (supporting its sensitivity). Preliminary results support the possibility of discriminating between visual and cognitive workload, as well as sensitivity to learning effects
Overestimation of Skills Affects Drivers’ Adaptation to Task Demands
Get PDFInadequate self-assessment, and specifically, overestimation of skill, results in insufficient adaptation to task demands, which can manifest itself on different levels of the driving task. A total of 130 drivers (83 novice and 47 experienced drivers) participated in an on-road driving assessment. Their performance in this assessment (i.e., fail or pass) was compared to the participants’ reported confidence in their driving skills (i.e., high or low confidence), resulting in three calibration groups: a) well-calibrated drivers (reported confidence matched performance on assessment), b) overconfident drivers (high confidence but failed assessment) and c) insecure drivers (low confidence but passed assessment). Furthermore, participants completed a questionnaire which focused on choices made on the strategic and manoeuvring level of the driving task. No significant difference was found between the calibration groups for the strategic level. Overconfident drivers reported significantly more violating behaviour than the well-calibrated and the insecure drivers. At the manoeuvring level, overconfident drivers showed significantly less instances of adaptation to traffic complexity. In conclusion, the current study suggests that overconfidence is related to inadequate adaptation to task demands
Prediction of Brake Onset Times for Rear End Collisions
No full textDriving has become an integral part of our daily lives, and so too have the dangers associated with driving. Understanding driver behavior could lead to system modifications to alleviate some of these inherent dangers. Specifically, prediction of driver braking behavior might be used to improve automatic braking systems and adaptive cruise control systems. The research presented in this paper details the development of an algorithm to predict the brake onset times in situations where rear-end collisions might occur. The algorithm is adaptive to an individual and not set to generic values. This algorithm was generated using data from a previous study (Kelling, 2006). Displayed stimuli consisted of different situations for a lead vehicle (stopped, slower moving, and reversing lead vehicle), multiple rates of closure (32.2, 64.4, and 96.6 kph), and two luminance conditions (day or night driving). Brake onset times were recorded. A self-modifiable algorithm was developed and was found to have an R-squared value of .625. The degree of goodness-of-fit for this algorithm is worthy of note because it also considers differences in the driving environment. The individualized adaptive ability of the algorithm provides a greater overall fit for predicting braking behavior, and it may be more useful in automated systems than existing algorithms
Using the Lane-Change Test (LCT) to Assess Distraction: Tests of Visual-Manual and Speech-Based Operation of Navigation System Interfaces
No full textThe Lane Change Test (LCT) is an easy-to-implement, low-cost methodology for the evaluation of the distraction associated with performing invehicle tasks while driving (Mattes, 2003). In the present study, the LCT was used to assess driving performance when drivers completed navigation tasks using visual-manual or speech-based interfaces. Drivers performed two types of navigation tasks at two levels of difficulty. The results provide support for the LCT as an effective measure of distraction for both types of interface. It is recommended that the LCT procedure incorporate additional measures beyond the current mean deviation measure. Two measures are suggested: Lane Change Initiation, which reflects the aspects of driving having to do with detection and response delay as a result of distraction, and a measure of task duration to account for risk exposure
Can Galvanic Vestibular Stimulation Reduce Simulator Adaptation Syndrome?
Get PDFElectrical stimulation of the vestibular sensory system during virtual environment simulations has been proposed as a method to reduce the incidence of simulator adaptation syndrome (SAS). However, there is limited empirical evidence to support this hypothesis. It is especially important to provide vestibular stimulation in driving simulators because an absence of vestibular cues may alter driver behaviour and reduce vehicle control. This study examined the application of galvanic vestibular stimulation (GVS) as a technique to reduce symptoms of SAS and improve vehicular control in a fixed-based driving simulator. Nineteen participants drove two visually distinct virtual environments (high and low visual cues). In addition, each of these worlds was experienced with and without GVS. Post-drive scores on the Simulator Sickness Questionnaire (SSQ) were used to evaluate the effect of GVS on SAS. In addition, three driving variables were measured to examine driving performance: steering variability, lane departures, and average vehicular speed. GVS application while driving resulted in significant decreases in total SSQ and disorientation symptoms. Greater vehicular control was also observed (as shown by reduced steering variability) when GVS was used in combination with visual cues along the simulated edge of the road. These results support that GVS may be used in fixed-base driving simulators to create vestibular motion cues and reduce SAS