Obstacle avoidance under automated steering: Impact on driving and gaze behaviours

Within the context of more and more autonomous vehicles, an automatic lateral control device (AS: Automatic Steering) was used to steer the vehicle along the road without drivers’ intervention. The device was not able to detect and avoid obstacles. The experiment aimed to analyse unexpected obstacle avoidance manoeuvres when lateral control was delegated to automation. It was hypothesized that drivers skirting behaviours and eye movement patterns would be modified with automated steering compared with a control situation without automation. Eighteen participants took part in a driving simulator study. Steering behaviours and eye movements were analysed during obstacle avoidance episodes. Compared with driving without automation, skirting around obstacles was found to be less effective when drivers had to return from automatic steering to manual control. Eye movements were modified in the presence of automatic steering, revealing further ahead visual scanning of the driving environment. Resuming manual control is not only a problem of action performance but is also related to the reorganisation of drivers’ visual strategies linked to drivers’ disengagement from the steering task. Assistance designers should pay particular attention to potential changes in drivers’ activity when carrying out development work on highly automated vehicles.     

Eye movements and hazard perception in active and passive driving

ABSTRACT

Differences in eye movement patterns are often found when comparing passive viewing paradigms to actively engaging in everyday tasks. Arguably, investigations into visuomotor control should therefore be most useful when conducted in settings that incorporate the intrinsic link between vision and action. We present a study that compares oculomotor behaviour and hazard reaction times across a simulated driving task and a comparable, but passive, video-based hazard perception task. We found that participants scanned the road less during the active driving task and fixated closer to the front of the vehicle. Participants were also slower to detect the hazards in the driving task. Our results suggest that the interactivity of simulated driving places increased demand upon the visual and attention systems than simply viewing driving movies. We offer insights into why these differences occur and explore the possible implications of such findings within the wider context of driver training and assessment.     

The development of hazard perception: Dissociation of visual orientation and hazard processing

Eye movements are a key behavior for visual information processing in traffic situations and for vehicle control. Previous research showed that effective ways of eye guidance are related to better hazard perception skills. Furthermore, hazard perception is reported to be faster for experienced drivers as compared to novice drivers. However, little is known whether this difference can be attributed to the development of visual orientation, or hazard processing. In the present study, we compared eye movements of 20 inexperienced and 20 experienced drivers in a hazard perception task. We separately measured (a) the interval between the onset of a static hazard scene and the first fixation on a potential hazard, and (b) the interval between the first fixation on a potential hazard and the final response. While overall RT was faster for experienced compared to inexperienced drivers, the scanning patterns revealed that this difference was due to faster processing after the initial fixation on the hazard, whereas scene scanning times until the initial fixation on the hazard did not differ between groups.     

The interactive effect of vehicle signals and sensation-seeking on driver hazard perception

Does sensation seeking—as a personality trait that is closely related to risky driving—affect a driver's hazard perception, and if so, under what circumstances? Using hazard locations and vehicle signals as cues, this study classifies traffic situations into four types: danger ahead with cues, danger ahead without cues, danger behind with cues, and danger behind without cues. Based on these classifications, we examine the characteristics of hazard perception, decision-making criteria, sensitivity, and visual attention patterns of drivers with different sensation-seeking tendencies. Fifty-two experienced drivers were recruited for experiments in Dalian, China. Using computer, participants were shown videos taken from the driver's perspective and were asked to respond to hazards by pressing keys on the left mouse button. Their eye movements were recorded, and a multi-dimensional driving-style scale was used to divide participants into higher and lower sensation-seeking groups. The results showed that the higher sensation-seeking drivers had a lower hazard detection rate, fewer fixation counts, and shorter glances when there were cues, and they responded more slowly when there was danger ahead. For dangers ahead with cues and dangers behind without cues, the more attention the higher sensation-seeking drivers paid to the danger, the slower their response and the lower their hazard detection rate. The results indicated that higher sensation-seeking drivers have poor hazard perception in situations when there are vehicle signals as prompting clues and dangers ahead. In particular, for a danger with clues, the visual agility of the higher sensation-seeking drivers was worse than that of the lower sensation-seeking drivers. The more attention they paid to the danger the worse their hazard perception. The results of this study can provide guidance to teach drivers hazard-perception skills.     

影响驾驶安全的驾驶员危险知觉研究述评

危险知觉是指驾驶员对交通情境中的潜在危险进行识别并做出反应的一种能力。目前,驾驶员危险知觉测量主要使用反应时、眼动或主观评定三种测量方法。在测量中,这三种方法各有优缺点,并出现相互结合的研究趋势。为了提高我国交通安全性,结合国外在提高驾驶员危险预期能力和改善视觉搜索模式两个方面的应用研究,未来国内研究可以在探索危险知觉的认知加工特点、影响因素及加快测量技术的商品化应用等方面加以深入。     

Driving simulator validation with hazard perception

How should we assess the comparability of driving on a road and “driving” in a simulator? If similar patterns of behaviour are observed, with similar differences between individuals, then we can conclude that driving in the simulator will deliver representative results and the advantages of simulators (controlled environments, hazardous situations) can be appreciated. To evaluate a driving simulator here we compare hazard detection while driving on roads, while watching short film clips recorded from a vehicle moving through traffic, and while driving through a simulated city in a fully instrumented fixed-base simulator with a 90 degree forward view (plus mirrors) that is under the speed/direction control of the driver. In all three situations we find increased scanning by more experienced and especially professional drivers, and earlier eye fixations on hazardous objects for experienced drivers. This comparability encourages the use of simulators in drivers training and testing.     

A method to improve the hazard perception of young novice drivers based on Bandura’s observational learning theory: Supplement to expert commentary training

Compared with experienced drivers, young novice drivers are more likely to have traffic accidents. The main reasons are that they lack experience, their hazard perception is weak, and their visual search strategy is underdeveloped. Research shows that hazard perception training can improve the visual search strategy of young novice drivers and enhance their hazard perception ability. We propose that a driver's visual search behaviour, like any other action, can be developed by observing the behaviour of a role model. In an experiment based on a driving simulator, we clustered the visual search paths of 20 experienced drivers, selected the drivers with the best visual search behaviour, and obtained visual search path video footage to produce hazard perception training videos. Using these videos, we applied Bandura’s observation learning theory to train 20 young novice drivers. We call this approach “training based on experienced drivers' performance”. To determine the effects of training based on experienced drivers' performance, 20 young novice drivers were given the usual expert commentary training, and 20 young drivers were given no training. The results showed that training based on experienced drivers' performance and expert commentary training had positive effects on the average speed of young novice drivers through hazard sections. Compared with untrained young novice drivers, trained young novice drivers decreased their speed in response to dangerous road sections. Compared with young novice drivers who received expert commentary training and those who did not receive training, young novice drivers who received training based on experienced drivers' performance showed significant improvements in visual search. These results suggest that training based on experienced drivers' performance can help young novice drivers improve their hazard perception, especially in visual aspects. This training method can complement existing training methods for young novice drivers.     

Detecting drivers’ cognitive load from saccadic intrusion

In this paper, we have explored use of Saccadic Intrusion to detect drivers’ cognitive load and instantaneous perception of developing road hazards. Saccadic Intrusion is a type of eye gaze movement which was earlier found to be related to change in cognitive load. We have developed an algorithm to detect saccadic intrusion from a commercially available low-cost eye gaze tracker and conducted four user studies involving a driving simulator and cognitive and hazard perception tests. Our results show that average velocities of saccadic intrusion increases with increase in cognitive load and recording saccadic intrusion and eye blinks for 6 s duration can predict drivers’ instantaneous perception of developing road hazards.     

Attending to the peripheral world while driving

Do inexperienced drivers see less of the world when driving? Previous research suggests that participants detect fewer peripheral targets while watching video clips of dynamic hazardous driving scenes due to increases in foveal demand (i.e. the presence of a hazard), increases in peripheral target eccentricity, and the lack of driving experience. The current study aimed to further explore the role of experience as a key factor in the potential narrowing of spatial attention, and the possibility of differences in the time course of attentional deployment. It was predicted that the amount of narrowing due to central processing demands would change as a function of driving experience, with more experienced drivers suffering less narrowing due to their mastery of central processing demands in road scenes. The data did not support the narrowing hypothesis, though they did support the alternative strategic difference between the driver groups in the time‐course of attentional deployment. Learners seem to suffer attentional degradation in extra‐foveal regions over a longer period of time whereas experienced drivers seem to invest peripheral attention at the hazard location in short but intense bursts. Copyright © 2002 John Wiley & Sons, Ltd.     

Attention during visual secondary tasks in driving: Adaptation to the demands of the driving task

Visual attention in driving with visual secondary task is compared for two visual secondary tasks. N = 40 subjects completed a 1 h test drive in a motion-base driving simulator. During the drive, participants either solved an externally paced, highly demanding visual task or a self paced menu system task. The secondary tasks were offered in defined critical and non-critical driving situations. Eye movement behavior was analyzed and compared for both tasks. Before starting the secondary tasks, eye movement behavior shows a smaller standard deviation of gaze as well as longer fixation durations for both tasks. The comparison between the two tasks indicates that drivers use the possibilities the self paced task offers: during the secondary task, they monitor the driving scene with longer fixations and show a greater standard deviation of gaze position. Furthermore, independently of the type of secondary task, drivers adapt their eye movement behavior to the demands of the situation. In critical driving situations they direct a larger proportion of glance time to the driving task. Last, the relation between glance behavior and collisions is analyzed. Results indicate that collisions go together with an inadequate distribution of attention during distraction. The results are interpreted regarding the attentional processes involved in driving with visual secondary tasks. Based on the similarities and differences between the two secondary tasks, a cognitive approach is developed which assumes that the control of attention during distraction is based on a mental situational model of the driving situation.     

Does driving experience in video games count? Hazard anticipation and visual exploration of male gamers as function of driving experience

Risk perception and distribution of visual attention while driving are crucial elements for accident prevention and new-driver improvement. This study investigates how racing videogames could shape the visual exploration of virtual and real road in male pre-drivers. The visual performance of players of racing video games with and without driver’s license was tested in virtual vs. real scenarios. Attention to specific elements of different types of road interactions was monitored using an eye-tracking system. Results showed that habitual use of racing video games was not found to foster a positive effect on users’ distribution of visual attention, supporting visual patterns typical of novice drivers. Gamers without driving experience replicated the same patterns in a real road scenario, ignoring road signs and potential areas of interactions with other drivers, while experienced drivers gamers explored video games roads like real roads. The fact that the gamers’ driving performance was not comparable to drivers in the virtual scenario suggests that there are other variables in the gameplay that create a less complex traffic scene, still the visual complexity of different real road interactions is kept in video game interactions, opening new perspectives towards gamers’ visual exploration of the road.     

自我评估的能力与驾驶经验对危险知觉的影响

结合反应时和眼动研究方法,采用驾驶经验2（新手,有经验）×自我评估的能力2（高,低）×危险类型2（明显,隐藏）的混合实验设计,探索驾驶员驾驶能力的自我评估和驾驶经验对危险知觉及视觉注意的影响。采用驾驶能力量表和基于动态交通视频的危险知觉任务对86名驾驶员测试,并使用Tobbi T120记录眼动数据。结果发现,新手和有经验驾驶员自我评估的能力与危险知觉反应时间之间相关不显著,这说明两组驾驶员对自己驾驶能力的认识和评估不准确。有经验驾驶员对两类危险的反应比新手快。新手自我评估的能力过高,他们对两类危险的反应比同龄驾驶员和有经验驾驶员慢。然而,有经验驾驶员自我评估的能力与危险知觉反应时间之间不存在显著差异。此外,与新手相比,有经验驾驶员对两类危险的首次注视较快,总注视时间更长。与同龄驾驶员相比,新手自我评估的能力过高,他们对危险的首次注视较慢,对危险的总注视时间更少。这些研究结果表明,新手自我评估的能力过高,可能会提高他们的风险接受阈限,由此降低了他们对危险的反应速度。未来驾驶训练应当采取措施减少新手对驾驶能力的自我评估偏见,改善他们的视觉搜索模式以降低事故风险。     

Spatial asymmetries in viewing and remembering scenes: Consequences of an attentional bias?

Given a single fixation, memory for scenes containing salient objects near both the left and right view boundaries exhibited a rightward bias in boundary extension (Experiment 1). On each trial, a 500-msec picture and 2.5-sec mask were followed by a boundary adjustment task. Observers extended boundaries 5% more on the right than on the left. Might this reflect an asymmetric distribution of attention? In Experiments 2A and 2B, free viewing of pictures revealed that first saccades were more often leftward (62%) than rightward (38%). In Experiment 3, 500-msec pictures were interspersed with 2.5-sec masks. A subsequent object recognition memory test revealed better memory for left-side objects. Scenes were always mirror reversed for half the observers, thus ruling out idiosyncratic scene compositions as the cause of these asymmetries. Results suggest an unexpected leftward bias of attention that selectively enhanced the representations, causing a smaller boundary extension error and better object memory on the views’ left sides.     

伪忽视行为表现与神经基础及交通驾驶应用

伪忽视是健康个体存在轻微偏左的不对称空间注意。影响这个现象的因素主要包括刺激材料、年龄、认知负荷和知觉负荷等。其中, 眼动搜索习惯曾经被认为是伪忽视现象的主要因素, 甚至提出伪忽视是眼动偏好现象。但是, 最近文献研究普遍认为, 伪忽视不是眼动行为, 而是注意特质。近10年的大脑神经层面的证据发现, 右脑腹侧注意网络对左侧空间注意偏好有较大的贡献, 而且在神经传导束的证据中也发现右脑大纵束二型对左侧空间注意的激活程度高于其他两种类型的传导束。另外, 注意偏好的时间分辨率研究发现, 注意的左侧空间偏向发生在注意发生后的100~200 ms之内, 眼动搜索时间则是在1500 ms之内出现最大左偏。该现象的应用研究主要体现在交通驾驶员的注意能力和驾驶视觉搜索模式的关系研究。研究意义在于为安全交通提供两条原则, 首先, 道路交通驾驶环境设置要满足驾驶员的注意特质的需求; 其次, 通过合理干预, 可以抑制视觉搜索习惯, 培养安全的驾驶搜索模式。     

Young drivers’ perception of hazards: Variation with experience and day versus night

Young novice drivers have a relatively high crash risk for several years following initial licensing, and while all drivers are at greater risk at night, the night-time increase is greater for inexperienced drivers. Poor hazard perception has been identified as an important contributor to inexperienced drivers’ risk, but research on day-night differences in hazard perception for drivers varying in experience is lacking. This exploratory study investigated the nature of hazards reported by young inexperienced drivers versus more experienced and slightly older drivers. Hazards were not pre-identified by researchers; participants were simply provided with a general definition of ‘hazard’. Analysis focused on how experience level affected qualitative differences in the kinds of hazards reported, with particular focus on day-night differences.The 53 participants ranged in driving experience from learners through to 5+years post licensing, and in age from 16 to 30 years. They viewed 14 day- and night-time video clips of a diverse range of driving situations, pausing the video whenever they identified a hazard and then explaining why they had paused it at that point. Their responses were recorded. Content analysis of responses showed that more experienced drivers reported visibility-related hazards significantly more often than inexperienced ones, and significantly more so at night. They also commented significantly more on hazards related to tight bends in the road and significantly less on hazards concerning compliance with rules. Comments tended to be fewer with higher vehicle speeds, particularly for the least experienced drivers.Results are discussed in terms of how experience-related differences in drivers’ cognitive schemata and mental models are likely to affect hazard perception and crash risk, particularly at night. Some implications for driver training and license testing are suggested.     

驾驶员视觉注意对危险识别的影响及作用机制

驾驶中, 有效的视觉注意模式是驾驶员搜索与识别潜在道路危险的先决条件。通过分析驾驶员视觉注意对危险识别的影响, 提出情境意识假设与心理负荷假设。情境意识假设认为, 情境意识的质量决定了驾驶员视觉注意模式的灵活性, 进而影响危险识别。心理负荷假设认为, 心理负荷水平提高, 驾驶员视觉注意趋于集中, 不利于危险识别。建议未来研究可以在比较不同驾驶员情境意识的认知兼容性, 应用汽车驾驶自动化技术降低心理负荷以及检测并区分情境意识与心理负荷的影响等方面加以深入。     

Right visual field advantage for perceived contrast: Correlation with an auditory bias and handedness

Studies have suggested that supramodal attentional resources are biased rightward due to asymmetric spatial fields of the two hemispheres. This bias has been observed especially in right-handed subjects. We presented left and right-handed subjects with brief uniform grey visual stimuli in either the left or right visual hemifield. Consistent with the proposed asymmetry in attentional resources, right-handed subjects estimated right hemifield targets as having a higher contrast than physically identical stimuli presented in the left hemifield. Left-handed participants did not show a systematic rightward or leftward bias. However, the group of left-handed participants also took part in a dichotic listening experiment whose results showed that visual bias score correlated positively with ear-advantage in dichotic listening. Our results are consistent with the view that supramodal processing resources are biased towards the right hemispace, and that this bias is influenced by handedness.     

Right visual field advantage for perceived contrast: correlation with an auditory bias and handedness

Studies have suggested that supramodal attentional resources are biased rightward due to asymmetric spatial fields of the two hemispheres. This bias has been observed especially in right-handed subjects. We presented left and right-handed subjects with brief uniform grey visual stimuli in either the left or right visual hemifield. Consistent with the proposed asymmetry in attentional resources, right-handed subjects estimated right hemifield targets as having a higher contrast than physically identical stimuli presented in the left hemifield. Left-handed participants did not show a systematic rightward or leftward bias. However, the group of left-handed participants also took part in a dichotic listening experiment whose results showed that visual bias score correlated positively with ear-advantage in dichotic listening. Our results are consistent with the view that supramodal processing resources are biased towards the right hemispace, and that this bias is influenced by handedness.     

Roadside digital billboard advertisements: Effects of static,transitioning, and animated designs on drivers’ performance and attention

The aim of this study was to analyze and compare the effects of different types of digital billboard advertisements (DBAs) on drivers’ performance and attention allocation. Driver distraction is a major threat to driver safety. DBAs are one form of distraction in drivers’ outside environment. There are many different types of DBAs, such as static images, changing images, or videos. However, it is not clear to what extent each of these contributes to driver distraction. A total of 100 students participated in a controlled driving simulator experiment in an urban environment. Measures of driving performance were collected, as well as eye tracking and EEG as windows into attention allocation. The different types of DBAs investigated were static (a single image), transitioning (one static DBA replaces another), and animated (short videos). The statistical analysis demonstrated that there were significant differences in the effect of each type of DBA on drivers' performance (deviation from the center of the lane and reaction time), visual attention to the road (percent of fixations on the road, percent of fixations on DBAs, fixation duration on DBAs, and number of gazes on DBAs), and the EEG theta band and beta band. These results show that driving performance and attention to the road were both more negatively affected when drivers were exposed to transitioning and animated DBAs as compared to static DBAs. The results of this study provide guidance for the better design and regulation of DBAs in order to minimize driver distraction.     

Visual search patterns in trained and untrained novice drivers

As drivers become more experienced many changes have been observed in their patterns of visual search. Differences between novice and experienced drivers are particularly marked in demanding or hazardous road situations and this has led researchers to speculate that limitations in search patterns may explain some of the accidents where newly qualified drivers are involved. This paper reports a training intervention that informs novice drivers about their typical patterns of visual search and stresses the need for scanning multiple locations in the visual scene for sources of potential danger. Two groups of drivers were evaluated on three occasions over the course of their first year after gaining a full driving licence. The evaluations involved recording drivers' eye movements while driving a route on real roads in traffic, and while watching videos of hazardous situations. One of the groups received the training intervention before the second occasion of testing. The intervention produced notable changes in the drivers' search patterns in both situations though not all changes were still detectable at a final phase of testing three to six months after the intervention had been delivered.