Driving simulators provide researchers with a flexible, controllable, safe, and economical tool for a range of applications. A pivotal aspect in the application of driving simulators is the development of measures aimed at describing the behavior and performance of the driver and providing knowledge about the way drivers are controlling their vehicle, which ultimately will benefit road safety. The driver performance is traditionally described by measures of (simulated) vehicle data and measures of subjective evaluations. This thesis provides additional measures of visual attention and driver physiology aimed at describing the driver behavior. Frequently, these measures are analyzed in isolation of the driver and vehicle performance. This thesis aims to derive relationships between concurrently recorded eye-movement and driver behavior variables in closed-loop driving tasks.@en

Safety is one of the major areas of concerns today in the field of automotive development. Different safety measures have and are being introduced in order to improve driver/passenger and pedestrian safety. Advanced driver assist systems (ADAS) are therefore becoming increasingly important in their role of reducing driver crash risk. A shortcoming of the ADAS systems is that the variability in drivers based on skill and experience is not taken into account and the system is often designed for average or worst case driver performance thereby compromising on the dynamic behaviour of the vehicle. This study focuses on understanding and quantifying the differences in drivers. This knowledge of driver differences can be helpful in designing an adaptive ADAS by introducing the driver into the control loop. The study investigates differences between race-car drivers and normal (experienced) drivers in a high-speed driving task. The study analyses simulator data for 17 drivers on the Mallory Park test circuit. The driving task required the participants to drive around the circuit to achieve the fastest lap times. Analysis showed that higher steering activity and differences in path strategy were the main reasons for lower lap-times shown by the expert race drivers compared to the non-expert drivers. Steering metrics like average steering rate, steering jerk showed higher values for the expert group and distance traveled around the corner showed a different path strategy adopted by the experts. Both groups showed improvement in performance based on lap-times across the different sessions. Thus the study shows that expert and non-expert drivers have different steering behaviour and path strategy, which can be attributed to differences in driving experience, vehicle dynamics knowledge and vehicle control skills.@en

This study is an extension of a previous work where differences between race-car drivers and normal drivers has been investigated in a high-speed driving task. The study focused on gaining knowledge about driver differences that can be helpful in designing an adaptive ADAS by introducing the driver into the control loop. The present study takes this research forward and is oriented around finding the differences between novice and normal (experienced) drivers while performing a double lane change maneuver and a high-speed cornering task. The study aimed at finding parameters capable of differentiating the two groups with special emphasis on steering behaviour. Part A of the test procedure required the participants to complete a double lane change at various speeds (from 70km/h to 105km/h). Data analysis showed that late initial steering input given by the novices compared to the experienced drivers was the main reason for their poor performance. Steering metrics like timing of steering input, average steering rate and average steering jerk showed statistically significant differences between the two groups. Part B of the experiment required the participants to drive around a flat oval track to achieve the fastest lap times. Analysis showed that higher steering activity and differences in path strategy were the main reasons for lower lap-times shown by the experienced drivers compared to the novice drivers. Steering metrics like average steering rate, steering jerk showed higher values for the experienced group.

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Motorsport has developed into a professional international competition. However, limited research is available on the perceptual and cognitive skills of racing drivers. By means of a racing simulator, we compared the driving performance of seven racing drivers with ten non-racing drivers. Participants were tasked to drive the fastest possible lap time. Additionally, both groups completed a choice reaction time task and a tracking task. Results from the simulator showed faster lap times, higher steering activity, and a more optimal racing line for the racing drivers than for the non-racing drivers. The non-racing drivers’ gaze behavior corresponded to the tangent point model, whereas racing drivers showed a more variable gaze behavior combined with larger head rotations while cornering. Results from the choice reaction time task and tracking task showed no statistically significant difference between the two groups. Our results are consistent with the current consensus in sports sciences in that task-specific differences exist between experts and novices while there are no major differences in general cognitive and motor abilities.

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Speeding because of time pressure is a leading contributor to traffic accidents. Previous research indicates that people respond to time pressure through increased physiological activity and by adapting their task strategy in order to mitigate task demands. In the present driving simulator study, we investigated effects of time pressure on measures of eye movement, pupil diameter, cardiovascular and respiratory activity, driving performance, vehicle control, limb movement, head position, and self-reported state. Based on existing theories of human behavior under time pressure, we distinguished three categories of results: (1) driving speed, (2) physiological measures, and (3) driving strategies. Fifty-four participants drove a 6.9-km urban track with overtaking, car following, and intersection scenarios, first with no time pressure (NTP) and subsequently with time pressure (TP) induced by a time constraint and a virtual passenger urging to hurry up. The results showed that under TP in comparison to NTP, participants (1) drove significantly faster, an effect that was also reflected in auxiliary measures such as maximum brake position, throttle activity, and lane keeping precision, (2) exhibited increased physiological activity, such as increased heart rate, increased respiration rate, increased pupil diameter, and reduced blink rate, and (3) adopted scenario-specific strategies for effective task completion, such as driving to the left of the lane during car following, and early visual lookout when approaching intersections. The effects of TP relative to NTP were generally large and statistically significant. However, individual differences in absolute values were large. Hence, we recommend that real-time driver feedback technologies use relative instead of absolute criteria for assessing the driver’s state.@en

Driver distraction is a leading cause of crashes. The introduction of in-vehicle technology in the last decades has added support to the driving task. However, in-vehicle technologies and handheld electronic devices may also be a threat to driver safety due to information overload and distraction. Adaptive in-vehicle information systems may be a solution to this problem. Adaptive systems could aid the driver in obtaining information from the device (by reducing information density) or prevent distraction by not presenting or delaying information when the driver’s workload is high. In this paper, we describe an on-the-road evaluation of a real-time driver workload estimator that makes use of geo-specific information. The results demonstrate the relative validity of our experimental methods and show the potential for using location-based adaptive in-vehicle systems.@en

Previous research has shown that novice drivers have underdeveloped vehicle control skills and visual search strategies that differ from those of experienced drivers. However, little is known about how novices’ driving performance and gaze behavior jointly change over the course of practice. In this paper, we investigated changes in driving performance and gaze behavior of 52 novice drivers while gaining experience in the simulator. The participants completed four sessions of 6 to 8 minutes on a rural road containing multiple 90-degree curves, and their task was to drive as close as possible to the center of the right lane. The results showed that the standard deviation of lateral position (SDLP) and steering activity significantly reduced from the first to the fourth session. The eye-tracking data showed that participants increased their spread of visual search and reduced gaze tunneling. Participants’ self-reported workload decreased from the first to the fourth session. Additionally, our results demonstrate that participants increased their gaze tunneling as a function of driving speed. In conclusion, during the first approximately 30 minutes of driving experience in a driving simulator, SDLP decreases, gaze variance increases, and self-reported workload decreases. These results indicate that short-term changes in driver skill and visual behavior of novice drivers can be detected using driving simulators.@en

Technological developments have led to increased visual fidelity of driving simulators. However, simplified visuals have potential advantages, such as improved experimental control, reduced simulator discomfort and increased generalisability of results. In this driving simulator study, we evaluated the effects of visual fidelity on driving performance, gaze behaviour and subjective discomfort ratings. Twenty-four participants drove a track with 90° corners in (1) a high fidelity, textured environment, (2) a medium fidelity, non-textured environment without scenery objects and (3) a low-fidelity monochrome environment that only showed lane markers. The high fidelity level resulted in higher steering activity on straight road segments, higher driving speeds and higher gaze variance than the lower fidelity levels. No differences were found between the two lower fidelity levels. In conclusion, textures and objects were found to affect steering activity and driving performance; however, gaze behaviour during curve negotiation and self-reported simulator discomfort were unaffected.

Practitioner Summary: In a driving simulator study, three levels of visual fidelity were evaluated. The results indicate that the highest fidelity level, characterised by a textured environment, resulted in higher steering activity, higher driving speeds and higher variance of horizontal gaze than the two lower fidelity levels without textures.@en

The young driver problem requires remedial measures against speeding and overconfidence. Previous research has shown that increasing the task difficulty during training can enhance subsequent retention performance and prevent overconfidence. In this driving simulator study, we evaluated the training effectiveness of vertical field of view restriction during a self-paced lane-keeping task. Sixty-two young, inexperienced drivers were divided into three groups: a near view (NV) group (upper part of the screen was blanked), a far view (FV) group (lower part of the screen was blanked), and a control group driving with full sight. All groups drove three training sessions lasting 8 min each on a curved rural road, followed by two retention sessions with full sight. The first retention session took place on the same rural road and the second session on a highway. Compared to the control group, the NV group drove with lower mean speed and had more road departures during training. Furthermore, NV drivers reported significantly lower confidence during the training sessions and the second retention session. NV drivers directed their eye gaze more closely to the vehicle during training and both retention sessions. FV drivers approached corners with lower speed compared to the control group during training and had a higher number of rapid steering wheel turns during training and both retention sessions. In conclusion, removing visual information resulted in lower reported self-confidence (NV) and altered steering behavior (FV) in retention sessions compared to driving with full sight. Furthermore, NV training caused drivers to direct their gaze closely to the vehicle during retention, which may be negative for road safety. Possible effects of simulator-based driver training on eye-scanning and safety are discussed.@en

Novice drivers tend to direct their gaze to the road ahead and not scan the environment properly. This study investigated the training effectiveness of a visual search task in a driving simulator, aimed at increasing young drivers' spread of visual search. Two groups of inexperienced drivers were instructed to drive as accurately as possible in the center of the right lane in a self-paced driving task of four 6-min sessions in a rural environment. While driving, one group performed a visual search task, consisting of detecting and fixating on visual stimuli in the peripheral area. The stimuli were purple dots that faded in slowly and disappeared when fixated by the participant. After training, both groups drove a transfer session in an urban environment, in which various hazardous situations occurred. Results showed that both groups improved their lane keeping performance, whereas the training group became more proficient in the visual search task. However, in the transfer session no group differences were detected. In conclusion, despite improvements in visual search performance during a relatively short training period, the visual search training did not detectibly influence the spread of visual search of novice drivers during a post training transfer session.@en

The objective of this study was to evaluate differences in driving performance, visual detection performance, and eye-scanning behavior between glaucoma patients and control participants without glaucoma. Glaucoma patients (n = 23) and control participants (n = 12) completed four 5-min driving sessions in a simulator. The participants were instructed to maintain the car in the right lane of a two-lane highway while their speed was automatically maintained at 100 km/h. Additional tasks per session were: Session 1: none, Session 2: verbalization of projected letters, Session 3: avoidance of static obstacles, and Session 4: combined letter verbalization and avoidance of static obstacles. Eye-scanning behavior was recorded with an eye-tracker. Results showed no statistically significant differences between patients and control participants for lane keeping, obstacle avoidance, and eye-scanning behavior. Steering activity, number of missed letters, and letter reaction time were significantly higher for glaucoma patients than for control participants. In conclusion, glaucoma patients were able to avoid objects and maintain a nominal lane keeping performance, but applied more steering input than control participants, and were more likely than control participants to miss peripherally projected stimuli. The eye-tracking results suggest that glaucoma patients did not use extra visual search to compensate for their visual field loss. Limitations of the study, such as small sample size, are discussed.@en