Natasha Merat

Highly Automated Driving, Secondary Task Performance, and Driver State

Objective: A driving simulator study compared the effect of changes in workload on performance in manual and highly automated driving. Changes in driver state were also observed by examining variations in blink patterns. Background: With the addition of a greater number of advanced driver assistance systems in vehicles, the driver’s role is likely to alter in the future from an operator in manual driving to a supervisor of highly automated cars. Understanding the implications of such advancements on drivers and road safety is important. Method: A total of 50 participants were recruited for this study and drove the simulator in both manual and highly automated mode. As well as comparing the effect of adjustments in driving-related workload on performance, the effect of a secondary Twenty Questions Task was also investigated. Results: In the absence of the secondary task, drivers’ response to critical incidents was similar in manual and highly automated driving conditions. The worst performance was observed when drivers were required to regain control of driving in the automated mode while distracted by the secondary task. Blink frequency patterns were more consistent for manual than automated driving but were generally suppressed during conditions of high workload. Conclusion: Highly automated driving did not have a deleterious effect on driver performance, when attention was not diverted to the distracting secondary task. Application: As the number of systems implemented in cars increases, an understanding of the implications of such automation on drivers’ situation awareness, workload, and ability to remain engaged with the driving task is important.

Control Task Substitution in Semiautomated Driving: Does It Matter What Aspects Are Automated?

Objective: The study was designed to show how driver attention to the road scene and engagement of a choice of secondary tasks are affected by the level of automation provided to assist or take over the basic task of vehicle control. It was also designed to investigate the difference between support in longitudinal control and support in lateral control. Background: There is comparatively little literature on the implications of automation for drivers’ engagement in the driving task and for their willingness to engage in non-driving-related activities. Method: A study was carried out on a high-level driving simulator in which drivers experienced three levels of automation: manual driving, semiautomated driving with either longitudinal or lateral control provided, and highly automated driving with both longitudinal and lateral control provided. Drivers were free to pay attention to the roadway and traffic or to engage in a range of entertainment and grooming tasks. Results: Engagement in the nondriving tasks increased from manual to semiautomated driving and increased further with highly automated driving. There were substantial differences in attention to the road and traffic between the two types of semiautomated driving. Conclusion: The literature on automation and the various task analyses of driving do not currently help to explain the effects that were found. Lateral support and longitudinal support may be the same in terms of levels of automation but appear to be regarded rather differently by drivers.

Preface to the Special Section on Human Factors and Automation in Vehicles Designing Highly Automated Vehicles With the Driver in Mind

Objective: This special section brings together diverse research regarding driver interaction with advanced automotive technology to guide design of increasingly automated vehicles. Background: Rapidly evolving vehicle automation will likely change cars and trucks more in the next 5 years than the preceding 50, radically redefining what it means to drive. Method: This special section includes 10 articles from European and North American researchers reporting simulator and naturalistic driving studies. Results: Little research has considered the consequences of fully automated driving, with most focusing on lane-keeping and speed control systems individually. The studies reveal two underlying design philosophies: automate driving versus support driving. Results of several studies, consistent with previous research in other domains, suggest that the automate philosophy can delay driver responses to incidents in which the driver has to intervene and take control from the automation. Understanding how to orchestrate the transfer or sharing of control between the system and the driver, particularly in critical incidents, emerges as a central challenge. Conclusion: Designers should not assume that automation can substitute seamlessly for a human driver, nor can they assume that the driver can safely accommodate the limitations of automation. Designers, policy makers, and researchers must give careful consideration to what role the person should have in highly automated vehicles and how to support the driver if the driver is to be responsible for vehicle control. As in other domains, driving safety increasingly depends on the combined performance of the human and automation, and successful designs will depend on recognizing and supporting the new roles of the driver.

Crossmodal links between audition and touch in covert endogenous spatial attention.

We report three experiments designed to investigate the nature of any crossmodal links between audition and touch in sustained endogenous covert spatial attention, using the orthogonal spatial cuing paradigm. Participants discriminated the elevation (up vs. down) of auditory and tactile targets presented to either the left or the right of fixation. In Experiment 1, targets were expected on a particular side in just one modality; the results demonstrated that the participants could spatially shift their attention independently in both audition and touch. Experiment 2 demonstrated that when the participants were informed that targets were more likely to be on one side for both modalities, elevation judgments were faster on that side in both audition and touch. The participants were also able to “split” their auditory and tactile attention, albeit at some cost, when targets in the two modalities were expected on opposite sides. Similar results were also reported in Experiment 3 when participants adopted a crossedhands posture, thus revealing that crossmodal links in audiotactile attention operate on a representation of space that is updated following posture change. These results are discussed in relation to previous findings regarding crossmodal links in audiovisual and visuotactile covert spatial attentional orienting.

Using vision to control locomotion: looking where you want to go.

Looking at the inside edge of the road when steering a bend seems to be a well-established strategy linked to using a feature called the tangent point. An alternative proposal suggests that the gaze patterns observed when steering result from looking at the points in the world through which one wishes to pass. In this explanation fixation on or near the tangent point results from trying to take a trajectory that cuts the corner. To test these accounts, we recorded gaze and steering when taking different paths along curved roadways. Participants could gauge and maintain their lateral distance, but crucially, gaze was predominantly directed to the region proximal to the desired path rather than toward the tangent point per se. These results show that successful control of high-speed locomotion requires fixations in the direction you want to steer rather than using a single road feature like the tangent point.

CityMobil: Human Factor Issues Regarding Highly Automated Vehicles on eLane

There are several human factor concerns with highly autonomous or semiautonomous driving, such as transition of control, loss of skill, and dealing with automated system errors. Four CityMobil experiments studied the eLane concept for dual-mode cars, and the results of one are described. The open eLane concept brings together road infrastructure and technical developments in vehicle automation to allow automated driving. The goal for the driving simulator experiment was to design and test the difference between a vocal and an acoustic user interface for a dual-mode vehicle driven both manually and automatically. In the experiment (n = 24), driver behavior was observed with a focus on the transition of control and the occurrence of system errors. Performance of transition of control was adequate for both interfaces at the beginning and end of an eLane. In the case of system failure, 15% of drivers failed to take control of the car in time for both interfaces. However, of those who did regain control, drivers with the vocal interface were faster. Moreover, a subjective questionnaire showed that the vocal interface was perceived as more positive than the acoustic interface. The study suggests that the vocal interface was preferred by participants and can be recommended for the human-machine interface of dual-mode vehicles, especially for providing warnings about system malfunctioning.There are several human factor concerns with highly autonomous or semiautonomous driving, such as transition of control, loss of skill, and dealing with automated system errors. Four CityMobil experiments studied the eLane concept for dual-mode cars, and the results of one are described. The open eLane concept brings together road infrastructure and technical developments in vehicle automation to allow automated driving. The goal for the driving simulator experiment was to design and test the difference between a vocal and an acoustic user interface for a dual-mode vehicle driven both manually and automatically. In the experiment (n = 24), driver behavior was observed with a focus on the transition of control and the occurrence of system errors. Performance of transition of control was adequate for both interfaces at the beginning and end of an eLane. In the case of system failure, 15% of drivers failed to take control of the car in time for both interfaces. However, of those who did regain control, drivers with the vocal interface were faster. Moreover, a subjective questionnaire showed that the vocal interface was perceived as more positive than the acoustic interface. The study suggests that the vocal interface was preferred by participants and can be recommended for the human–machine interface of dual-mode vehicles, especially for providing warnings about system malfunctioning.

The role of gaze and road edge information during high-speed locomotion.

Robust control of skilled actions requires the flexible combination of multiple sources of information. Here we examined the role of gaze during high-speed locomotor steering and in particular the role of feedback from the visible road edges. Participants were required to maintain one of three lateral positions on the road when one or both edges were degraded (either by fading or removing them). Steering became increasingly impaired as road edge information was degraded, with gaze being predominantly directed toward the required road position. When either of the road edges were removed, we observed systematic shifts in steering and gaze direction dependent upon both the required road position and the visible edge. A second experiment required fixation on the road center or beyond the road edges. The results showed that the direction of gaze led to predictable steering biases, which increased as road edge information became degraded. A new steering model demonstrates that the direction of gaze and both road edges influence steering in a manner consistent with the flexible weighted combination of near road feedback information and prospective gaze information.

A human factors perspective on automated driving

ABSTRACT Automated driving can fundamentally change road transportation and improve quality of life. However, at present, the role of humans in automated vehicles (AVs) is not clearly established. Interviews were conducted in April and May 2015 with 12 expert researchers in the field of human factors (HFs) of automated driving to identify commonalities and distinctive perspectives regarding HF challenges in the development of AVs. The experts indicated that an AV up to SAE Level 4 should inform its driver about the AVs capabilities and operational status, and ensure safety while changing between automated and manual modes. HF research should particularly address interactions between AVs, human drivers and vulnerable road users. Additionally, driver-training programmes may have to be modified to ensure that humans are capable of using AVs. Finally, a reflection on the interviews is provided, showing discordance between the interviewees’ statements – which appear to be in line with a long history of HFs research – and the rapid development of automation technology. We expect our perspective to be instrumental for stakeholders involved in AV development and instructive to other parties.

Concord grape juice, cognitive function, and driving performance: a 12-wk, placebo-controlled, randomized crossover trial in mothers of preteen children

BACKGROUND Daily consumption of Concord grape juice (CGJ) over 3-4 mo has been shown to improve memory function in adults with mild cognitive impairment and reduce blood pressure in hypertensive adults. These benefits likely result from the high concentration of polyphenols in CGJ. Increased stress can impair cognitive function and elevate blood pressure. Thus, we examined the potential beneficial effect of CGJ in individuals with somewhat stressful and demanding lifestyles. OBJECTIVE We sought to examine the effects of the daily consumption of CGJ for 12 wk on cognitive function, driving performance, and blood pressure in healthy, middle-aged working mothers. DESIGN Twenty-five healthy mothers (aged 40-50 y) of preteen children who were employed for ≥30 h/wk consumed 12 ounces (355 mL) of either CGJ (containing 777 mg total polyphenols) or an energy-, taste-, and appearance-matched placebo daily for 12 wk according to a randomized crossover design with a 4-wk washout. Verbal and spatial memory, executive function, attention, blood pressure, and mood were assessed at baseline and at 6 and 12 wk. Immediately after the cognitive battery, a subsample of 17 women completed a driving performance assessment at the University of Leeds Driving Simulator. The 25-min driving task required participants to match the speed and direction of a lead vehicle. RESULTS Significant improvements in immediate spatial memory and driving performance were observed after CGJ relative to placebo. There was evidence of an enduring effect of CGJ such that participants who received CGJ in arm 1 maintained better performance in the placebo arm. CONCLUSIONS Cognitive benefits associated with the long-term consumption of flavonoid-rich grape juice are not exclusive to adults with mild cognitive impairment. Moreover, these cognitive benefits are apparent in complex everyday tasks such as driving. Effects may persist beyond the cessation of flavonoid consumption, and future studies should carefully consider the length of washout within crossover designs. This trial was registered at clinicaltrials.gov as NCT01411631.

Optic flow asymmetries bias high-speed steering along roads.

How do animals and insects use visual information to move through the world successfully? Optic flow, the pattern of motion at the eye, is a powerful source of information about self-motion. Insects and humans are sensitive to the global pattern of optic flow and try to maintain flow symmetry when flying or walking. The environments humans encounter, however, often contain demarcated paths that constrain future trajectories (e.g., roads), and steering has been successfully modeled using only road edge information. Here we examine whether flow asymmetries from a textured ground plane influences humans steering along demarcated paths. Using a virtual reality simulator we observed that different textures on either side of the path caused predictable biases to steering trajectories, consistent with participants reducing flow asymmetries. We also generated conditions where one textured region had no flow (either the texture was removed or the textured region was static). Despite the presence of visible path information, participants were biased toward the no-flow region consistent with reducing flow asymmetries. We conclude that optic flow asymmetries can lead to biased locomotor steering even when traveling along demarcated paths.