A test of the tau-dot hypothesis of braking control in the real world

A controlled experiment used instrumented vehicles in a real-world driving task to compare D. N. Lee's (1976) tau-dot hypothesis of braking control with an alternative based on the direct estimation and control of ideal deceleration (T. Yates, M. Harris, & P. Rock, 2004). Drivers braked to stop as closely as possible to a visual target from different starting speeds and times-to-contact. The data provided little support for the tau-dot hypothesis, and analysis suggested that braking in the real world is better explained by a direct deceleration strategy.     

Size estimates of action-relevant space remain invariant in the face of systematic changes to postural stability and arousal

Perceptual estimates of action-relevant space have been reported to vary dependent on postural stability and concomitant changes in arousal. These findings contribute to current theories proposing that perception may be embodied. However, systematic manipulations to postural stability have not been tested, and a causal relationship between postural stability and perceptual estimates remains to be proven. We manipulated postural stability by asking participants to stand in three differently stable postures on a force plate measuring postural sway. Participants looked at and imagined traversing wooden beams of different widths and then provided perceptual estimates of the beams’ widths. They also rated their level of arousal. Manipulation checks revealed that the different postures resulted in systematic differences in body sway. This systematic variation in postural stability was accompanied by significant differences in self-reported arousal. Yet, despite systematic differences in postural stability and levels of arousal perceptual estimates of the beams’ widths remained invariant.     

The scaling of information to action in visually guided braking

Braking to avoid a collision can be controlled by keeping the deceleration required to stop (i.e., ideal deceleration) in the "safe" region below maximum deceleration, but maximum deceleration is not optically specified and can vary as conditions change. When brake strength was manipulated between participants using a simulated braking task, the ratio of ideal to maximum deceleration at brake onset was invariant across groups, suggesting that calibration involves scaling information about ideal deceleration in intrinsic units of maximum deceleration. Evidence of rapid recalibration was found when brake strength was manipulated within participants, and the presence of external forces that affect brake dynamics resulted in biases in performance. Discussion focuses on the role of calibration, internal models, and affordance perception in visually guided action.     

The effect of visual and cognitive distraction on driver’s anticipation in a simulated car following scenario

Distraction is a common cause of accidents (e.g. NHTSA, 2009), and different distraction conditions influence the driving behaviour in a specific way. Despite a lot of research in this area, most studies concentrate on perception errors as a result of visual distraction. The effects of different distraction conditions on higher cognitive processes are still unclear. The fact that accidents happen even if the drivers perceive all relevant information implies that cognitive factors contribute to accidents, too. For this reason, this study was conducted to investigate how different distraction conditions influence the anticipation of events in a car–following scenario. Anticipation is required to know what will happen next, and to react adequately to the situation. In a driving simulator, scenarios with different manoeuvres of a preceding car were created to generate various anticipations and therefore a different adaptation of the driving behaviour. Additionally, a cognitive and a visual secondary task were introduced. The question was in which way either a cognitive or visual distraction influences the generation of anticipations and the construction of an appropriate situation model.The results indicate that in the phase when the preceding car showed braking manoeuvres, drivers prolonged their safety distance only when being visually distracted which is probably done to compensate for this visual distraction. This compensation ensued to some extent in the second phase where the preceding cars drove with a constant speed. Additionally, drivers who were visually distracted went somewhat slower when the car in front had braked in phase one. Thus, the drivers seemed to anticipate that the car might brake again and adapted their speed accordingly. This was not found in drivers with cognitive distraction. Thus, cognitive distraction seems to disturb this anticipation.Finally, at an intersection, drivers with visual distraction had a smaller TTC and a higher velocity when the car in front made an unexpected turn. Thus, the impairment of perception due to the visual distraction leads to a slower reaction as compared to a cognitive distraction. Overall, cognitive distraction influences the anticipation of possible future actions of other car drivers negatively while visual distraction deteriorates perception and thus the reaction to critical, sudden events. Thus, different intervention strategies are required to prevent these kinds of accidents.     

碰撞事件探测和躲避的心理分析

该文界定了由视觉信息所决定的“碰撞”和“制动操作”的概念,探讨了影响人们探测碰撞事件的各种心理认知因素。在此基础上进一步就机动车司机如何基于环境信息及个体和社会信息校正驾驶制动行为,以躲避碰撞、达到安全行驶的心理策略等问题进行了深入地剖析。     

Information used in detecting upcoming collision

In four experiments we examined the nature of the information used in judging whether events would or would not give rise to a collision in the near future. Observers were tested in situations depicting approaches between two objects (lateral approaches) and approaches between an object and the point of observation (head-on approaches), with objects moving according to constant deceleration or sinusoidal deceleration patterns. Judgments were found to be based, to a large extent, on the (in)sufficiency of current deceleration to avoid upcoming collision, as specified optically by tau-dot (tau). However, the information specified by tau (tau), that is the current (first-order) time remaining until contact, was also found to play a significant role. We deduce that judgment of upcoming collision is based on the detection of tau and its evolution over time, suggesting that observers are sensitive to delta(tau) rather than to tau itself.     

A comparison of experienced and novice drivers’ rear-end collision avoidance maneuvers under urgent decelerating events

A leading vehicle’s sudden deceleration can lead to a rear-end collision. Due to a lack of driving experience, novice drivers have a greater tendency to be involved in these accidents. Most previous studies have examined driver response time and braking behaviors, but few researchers have focused on what experienced and novice drivers did after their feet touched the braking pedal and their hands turned the steering wheel. These braking and steering parameters are essential in understanding driver avoidance behavior during emergencies. We programmed rear-end crash risk scenarios to examine experienced and novice drivers’ behaviors thoroughly using a driving simulator. Twenty experienced and twenty five novice subjects participated in our experiments, and their braking and steering maneuvers were recorded when leading vehicles ran at 60 km/h, 80 km/h and 100 km/h. The results showed that the two groups of subjects tended to execute two kinds of maneuvers to avoid crashes: braking only (novice 33%, experienced 19%) and the combination of braking with steering (novice 22%, experienced 26%). When the novice drivers executed braking with steering, their response time and steering duration were significantly longer than those of the experienced drivers who executed braking with steering. As the speed increased, the novice drivers’ response time, maximum braking force and maximum steering angle were significantly affected. These results showed that novice drivers should brake only when the leading vehicle suddenly decelerates. The experienced drivers executed steadier maneuvers. Their risk perception time was shorter, and their maximum braking force and the maximum steering angles were smaller. The response time, braking intensity and steering wheel angle should be considered when developing rear-end collision warning systems.     

Impact of Postural Stability and Modality on the Perception of Passage and Surface Climbing

The foundation for this study is the belief that an accurate understanding of affordance perception requires consideration of the observer-ground surface interface. More specifically, it is argued that variations in the organism-environment interface will affect postural stability that, in turn, will affect affordance judgments. It is further expected that the impact of variations in postural stability should be independent of the perceptual system employed by the perceiver. Participants in this study wore shoes meant to create varying degrees of postural stability and used either vision or sound to determine whether a gap afforded passage or a surface could be stepped upon. The results revealed that the manipulation of postural stability significantly affected judgments of passage and climbability. Although modality alone did not influence affordance judgments, it did so in combination with postural stability. Discussion is given to the notion that an accurate understanding of perception requires consideration of the perceiver and the environment as a single unit.     

Gaze Patterns in a Steering-Into-Lane Task on a Straight Road: The Effect of Driving Speed,Lane, and Expertise

The tau-dot hypothesis states that when tau-dot greater than or equal to -0.5, impact will be soft; when tau-dot < -0.5, impact will be "hard." Four experiments tested the usefulness of tau-dot for observers of collisions between 2 objects (rather than collisions between the observer and an object). Observers watched collisions depicted on a computer as 1 object approaching another. Results conformed to the tau-dot hypothesis and were consistent with previous research wherein observers watched collisions as participants. Results suggest that the information specifying collision severity is the rate of the relative rate of optical variation, a quantity that remains invariant over differing collision path trajectories and over differing perceivers (i.e., spectators or participants, viewing from different vantage points, moving or stationary).     

Perceptual learning and the visual control of braking

Performance on a visually guided action may improve with practice because observers become perceptually attuned to more reliable optical information. Fajen and Devaney (2006) investigated perceptual attunement, using an emergency braking task in which subjects waited until the last possible moment before slamming on the brakes. The subjects in that study learned to use more reliable optical variables with practice, allowing them to perform the task more successfully across changes in the size of the approached object and the speed of approach. In Experiment 1 of the present study, subjects completed blocks of normal, regulated braking before and after practice on emergency braking. Size and speed effects that were present at early stages diminished or were eliminated after practice, suggesting that perceptual attunement resulting from practice on emergency braking transfers to normal, regulated braking. In Experiment 2, practice on regulated braking alone also resulted in perceptual attunement. The findings suggest that braking is not always guided on the basis of an optical invariant and that perceptual attunement plays an important role in learning to perform a visually guided action.     

Calibration, information, and control strategies for braking to avoid a collision

This study explored visual control strategies for braking to avoid collision by manipulating information about speed of self-motion. Participants watched computer-generated displays and used a brake to stop at an object in the path of motion. Global optic flow rate and edge rate were manipulated by adjusting eye-height and ground-texture size. Stopping distance, initiation of braking, and the magnitude of brake adjustments were influenced by both optical variables, but global optic flow rate had a stronger effect. A new model is introduced according to which braking is controlled by keeping the perceived ideal deceleration, based in part on global optic flow rate, within a "safe" region between 0 and the maximum deceleration of the brake.     

Aging drivers and post delineated express lanes: Threading the needle at 70 miles per hour

Post-delineated express lanes represent a combination of driving complexities that are particularly difficult for older drivers to navigate. The narrow geometry and high speeds that are common to this treatment reflect a critical test for drivers whose depth perception, contrast sensitivity, and visual processing speed are reduced. The present study was designed to empirically examine the effects of age and color of express lane delineators on driver behavior. Three groups of participants (aged 18–39, 40–64, and 65 + years old) were required to complete a series of simulated driving scenarios consisting of combinations of single and dual lane configurations, with speed and lane position measured at the beginning and midpoint of each express lane. All drivers were pre-screened on various visual functioning abilities. Drivers in the 65 and older group show significant age-related declines in depth perception, contrast sensitivity, and phoria which were subsequently correlated with a wide range of driving measures including deceleration rate, brake time, jerk, speed, and lane position. Age related perceptual declines were statistically correlated with slower driving speed and wider lane deviations, including a statistically significant increase in the number of excursions beyond the typical 12-foot lane width. Based on these findings, the behavior of senior drivers was identified as a distinct design condition that should govern the design of high-speed, narrow geometric conditions. This age group requires wider lane widths, particularly at the beginning of single-lane post delimited sections, wider buffer areas around the post markers, and dual lane configurations wherever possible.     

Cell phone-induced failures of visual attention during simulated driving

This research examined the effects of hands-free cell phone conversations on simulated driving. The authors found that these conversations impaired driver's reactions to vehicles braking in front of them. The authors assessed whether this impairment could be attributed to a withdrawal of attention from the visual scene, yielding a form of inattention blindness. Cell phone conversations impaired explicit recognition memory for roadside billboards. Eye-tracking data indicated that this was due to reduced attention to foveal information. This interpretation was bolstered by data showing that cell phone conversations impaired implicit perceptual memory for items presented at fixation. The data suggest that the impairment of driving performance produced by cell phone conversations is mediated, at least in part, by reduced attention to visual inputs.     

An ecological Theory of Motion Sickness and Postural Instability

In this article we present a new theory of motion sickness. In the sensory conflict theory, changes in stimulation of perceptual systems are believed to be responsible for motion sickness. We discuss the fact that these changes in stimulation are not independent of the animal-environment interaction, but are determined by corresponding changes in the constraints operating on the control of action. Thus, provocative situations may be characterized by novel demands on the control of action as well as by novel patterns of stimulation. Our hypothesis is that animals become sick in situations in which they do not possess (or have not yet learned) strategies that are effective for the maintenance of postural stability. We identify a broad range of situations over which the occurrence of motion sickness is related to factors that should influence postural stability. This allows us to establish a logical link between motion sickness and postural stability. Our analysis implies that an understanding of stability should be an important part of the agenda in research on perception and action in general. We suggest that postural instability could be related to the concept of dynamical disease which has been developed in the literature on nonlinear physiological control systems. We conclude with suggestions for research based on the new approach.     

Postural stabilization of perceptual but not cognitive performance

In 2 experiments, the authors independently varied the degree of cognitive and perceptual difficulty of suprapostural tasks. Participants were 23 students in Experiment 1 and 15 in Experiment 2. Increases in perceptual difficulty tended to be correlated with decreases in the variability of postural sway, consistent with the hypothesized functional integration of postural control with suprapostural tasks. Sway variability was not influenced by changes in the cognitive difficulty of tasks when perceptual difficulty was held constant, contrary to predictions derived from the perspective that postural and suprapostural activities compete for a limited pool of central processing resources. The results underscore the need for researchers to differentiate between suprapostural tasks that require perceptual contact with the environment and those that do not.     

Visualizing the autonomous vehicle’s maneuvers – Does an ecological interface help to increase the hedonic quality and safety?

This paper examines whether ecological speed information describing ongoing driving maneuvers during automated driving enhances the hedonic quality and driving safety immediately after a driving takeover. Visualizing maneuvers and trajectories has already proven effective. However, planned acceleration and deceleration in an automated vehicle have not yet been investigated. Therefore, this paper assesses how an automated vehicle’s speed control information might be presented by an ecological interface. Besides a possible increase in the hedonic quality, this information might enhance safe behavior of the human driver when it comes to a takeover. To assess these two aspects, 43 drivers participated in a dynamic driving simulator study. Using a within-subject design, two scenarios were used to compare an ecological interface, dynamically visualizing speed changes, to a conventional pop-up interface, using pop-up icons to visualize speed changes. The experimental results indicate that ecological feedback and conventional pop-up feedback do not differ regarding the hedonic quality, which was reflected by the state anxiety, usefulness, and satisfaction with the overall human-machine interface (HMI). Nonetheless, the post-hoc questionnaire on situational awareness showed a significantly lower rating for the ecological interface which may be the result of a more automatic and subconscious processing of the information given. Analyzing the takeover performance, the initial takeover time was comparably low for both interfaces. However, concerning safety, the ecological interface significantly enhanced the lateral control after takeover, and the drivers looked at the vehicle mirrors significantly earlier. In conclusion, the results show that the information given by the ecological interface may help drivers cope with a sudden takeover in a faster and more controlled way. Future applications of these findings might serve to enhance the acceptance and safety of semi-autonomous vehicles by implementing ecological interfaces.     

Toward a greater understanding of Colombian professional truck drivers’ safety performance

In this investigation involving 227 lone professional truck drivers from a national transportation company in a low and moderate-income country (LMIC), Colombia, a multidimensional model of drivers’ safety performance and expectations concerning how safety performance dimensions would predict hard braking were evaluated. The results supported a multidimensional conceptualization of professional truck drivers’ safety performance, with factors aligned with confirmed general safety performance factors and occupation-specific factors. Furthermore, results supported the expectation that the dimensions associated with communicating safety information and complying with laws and regulations would predict hard braking over and above less conceptually relevant safety performance dimensions such as using personal protective equipment and preparing to drive, safety climate, and region of operation. Notably, a dimension of safety performance expected to promote workplace safety, the communication of health and safety information, was associated with increased hard braking. We discuss the implications of a multidimensional conceptualization and measure of safety performance for studying workplace safety for professional truck drivers in Colombian organizations and beyond.     

Enabling a man with multiple disabilities and limited motor behavior to perform a functional task with help of microswitch technology

This study evaluated the extent to which two microswitches used as interfaces would enable a man with multiple disabilities and limited motor behavior to operate an electric door opener at the entrance of the day center that he attended. Analysis showed the man (a) learned to use the two microswitches, (b) preferred the microswitch placed at his wheelchair's footrest (which also allowed more effective responding) over the microswitch placed at his wheelchair's armrest, and (c) maintained his positive performance at the 1- and 2-mo. postintervention checks. The results were discussed from a technical and practical standpoint and in terms of implications for the quality of life of persons with disabilities.     

碰撞时间估计的影响因素研究

本研究采用遮挡范式,考察了专职公交车驾驶员对不同类型、速度和方向运动物体的碰撞时间(TTC)估计.结果发现,被试对不同类别和速度运动物体的TTC估计有显著差异.这表明,除了视觉信息和物理信息之外,运动物体的概念信息也是影响横向运动TTC估计的重要因素.     

A driving simulator study to assess driver performance during a car-following maneuver after switching from automated control to manual control

A review of the literature on autonomous vehicles has shown that they offer several benefits, such as reducing traffic congestion and emissions, and improving transport accessibility. Until the highest level of automation is achieved, humans will remain an important integral of the driving cycle, which necessitates to fully understand their role in automated driving. A difficult research topic involves an understanding of whether a period of automated driving is likely to reduce driver fatigue rather than increase the risk of distraction, particularly when drivers are involved in a secondary task while driving. The main aim of this research comprises assessing the effects of an automation period on drivers, in terms of driving performance and safety implications. A specific focus is set on the car-following maneuver. A driving simulator experiment has been designed for this purpose. In particular, each participant was requested to submit to a virtual scenario twice, with level-three driving automation: one drive consisting of Full Manual Control Mode (FM); the other comprising an Automated Control Mode (AM) activated in the midst of the scenario. During the automation mode, the drivers were asked to watch a movie on a tablet inside the vehicle. When the drivers had to take control of the vehicle, two car-following maneuvers were planned, by simulating a slow-moving vehicle in the right lane in the meanwhile a platoon of vehicles in the overtaking lane discouraged the passing maneuver. Various driving performances (speeds, accelerations, etc.) and surrogate safety measures (PET and TTC) were collected and analysed, focusing on car-following maneuvers. The overall results indicated a more dangerous behavior of drivers who were previously subjected to driving automation; the percentage of drivers who did not apply the brakes and headed into the overtaking lane despite the presence of a platoon of fast-moving vehicles with unsafe gaps between them was higher in AM drive than in FM drive. Conversely, for drivers who preferred to brake, it was noted that those who had already experienced automated driving, adopted a more careful behavior during the braking maneuver to avoid a collision. Finally, with regard to drivers who had decided to overtake the braking vehicle, it should be noted that drivers who had already experienced automated driving did not change their behavior whilst overtaking the stopped lead vehicle.