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The recent development of motorcycle simulators has made it possible to study rider behavior in safe conditions. However, their use still raises validity issues. Our study examined how riders' steering and gaze behaviors and subjective experience are influenced by motorcycle roll tilt and reverse steering, which are considered to be essential factors in real-life motorcycle riding. The results revealed that tilting the motorcycle in the roll plane did not lead to significant changes in rider behavior, gaze sampling, or perceived realism. The steering control strategy adopted by riders did, however, significantly influence these results. A direct steering control strategy meant that riders took a racing path and scanned the road far in advance. When reverse steering was implemented, however, riders chose to take a "safety path", as recommended by training manuals. Reverse steering also received the highest realism score. However, steering control was more difficult, as shown by the larger number of lane departures recorded and a change in the trade-off between guiding and look-ahead fixations. This suggests that although reverse steering matches riders' real control behavior and improves the subjective experience of simulator riding, it is hindered by an inadequate internal model of vehicle dynamics. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

International audience; Autonomous navigation becomes complex when it is performed in an environment that lacks road signs and includes a variety of users, including vulnerable pedestrians. This article deals with the perception of collision risk from the viewpoint of a passenger sitting in the driver’s seat who has delegated the total control of their vehicle to an autonomous system. The proposed study is based on an experiment that used a fixed-base driving simulator. The study was conducted using a group of 20 volunteer participants. Scenarios were developed to simulate avoidance manoeuvres that involved pedestrians walking at 4.5 kph and an autonomous vehicle that was otherwise driving in a straight line at 30 kph. The main objective was to compare two systems of risk perception: These included subjective risk assessments obtained with an analogue handset provided to the participants and electrodermal activity (EDA) that was measured using skin conductance sensors. The relationship between these two types of measures, which possibly relates to the two systems of risk perception, is not unequivocally described in the literature. This experiment addresses this relationship by manipulating two factors: The time-to-collision (TTC) at the initiation of a pedestrian avoidance manoeuvre and the lateral offset left between a vehicle and a pedestrian. These manipulations of vehicle dynamics made it possible to simulate different safety margins regarding pedestrians during avoidance manoeuvres. The conditional dependencies between the two systems and the manipulated factors were studied using hybrid Bayesian networks. This relationship was inferred by selecting the best Bayesian network structure based on the Bayesian information criterion. The results demonstrate that the reduction of safety margins increases risk perception according to both types of indicators. However, the increase in subjective risk is more pronounced than the physiological response. While the indicators cannot be considered redundant, data modeling suggests that the two risk perception systems are not independent.

International audience; This article presents an activity analysis carried out in an aeronautical factory. The representation of the real process and the operators’ representations were identified. The representation of the real process was elaborated using an abstraction hierarchy, as described by the ecological interface design framework. The operators’ representations were extracted through interviews and observations and described in terms of schemes. The analysis revealed that operators in the studied factory used misleading schemes (i.e., false representations) to organize their activities, resultingin poor performance.We conclude by offering possible remedies, including training aimed at inhibiting the misleading scheme and a simulation tool to convey a more accurate representation.

International audience; When negotiating bends car drivers perform gaze polling: their gaze shifts between guiding fixations (GFs; gaze directed 1-2 s ahead) and look-ahead fixations (LAFs; longer time headway). How might this behavior change in autonomous vehicles where the need for constant active visual guidance is removed? In this driving simulator study, we analyzed this gaze behavior both when the driver was in charge of steering or when steering was delegated to automation, separately for bend approach (straight line) and the entry of the bend (turn), and at various speeds. The analysis of gaze distributions relative to bend sections and driving conditions indicate that visual anticipation (through LAFs) is most prominent before entering the bend. Passive driving increased the proportion of LAFs with a concomitant decrease of GFs, and increased the gaze polling frequency. Gaze polling frequency also increased at higher speeds, in particular during the bend approach when steering was not performed. LAFs encompassed a wide range of eccentricities. To account for this heterogeneity two sub-categories serving distinct information requirements are proposed: mid-eccentricity LAFs could be more useful for anticipatory planning of steering actions, and far-eccentricity LAFs for monitoring potential hazards. The results support the idea that gaze and steering coordination may be strongly impacted in autonomous vehicles.

This paper describes a newly developed driver model that focuses on the control of car steering. The model represents visual anticipation of road curvature and compensation of lateral positioning error. It also incorporates a neuromuscular system, inspired by Hoult and Cole (2008), including an internal model of the steering system compliance, muscle co-activation by α and γ signals and the stretch reflex. Preliminary driving simulator experiments with five participants showed that the identification of model parameters yielded consistent results. Moreover, the model was able to steer the driving simulator by itself and showed a behavior similar to that of the human driver who provided the data for parameter identification. This model may be used for the design of automation for shared control of steering.

In the perspective of full-windshield HUD in cars, this study investigated whether adding a guidance cue in the visual scene influences drivers' gaze strategies and steering behavior. Participants negotiated a series of bends with or without a visual beacon positioned on the tangent point or close to it. Results revealed that the stability of steering was improved when tracking of the beacon was enforced. The visual cue was not spontaneously used by the drivers and gaze strategy only showed minor changes in that case.

International audience; The goal of this study was to examine the effects of visual roll tilt on gaze and riding behavior when negotiating a bend using a motorcycle simulator. To this end, experienced motorcyclists rode along a track with a series of right and left turns whilst the degree of visual roll tilt was manipulated in three different conditions. Gaze behavior was analyzed by using the tangent point as a dynamic spatial reference; the deviation of gaze to this particular point was computed in both the horizontal and vertical directions. Steering control was assessed in terms of the lateral positioning, steering stability and number of lane departures. In the no-roll condition, the motorcyclists tracked a steering point on the road ahead, which was compatible with the hypothesis of ‘‘steer where you look” behavior. In the roll condition, our results revealed that the horizontal distribution of gaze points relative to the tangent point was preserved. However, significantly more fixations were made further ahead of the tangent point in the vertical direction. This modification of visual behavior was coupled with a degradation in steering stability and an offset in lateral positioning, which sometimes led to lane departures. These results are discussed with regard to models of visual control of steering for bend negotiation.

International audience; In the context of a remote collaboration task in virtual reality, this study aimed to analyze the effects of task distribution on the processing of spatial information and mental workload in spatial dialogs. Pairs of distant participants with specific roles (a guide and a manipulator) had to collaboratively move a virtual object in a plane factory mock-up. The displays allowed the participants to be immersed together in the virtual environment. We analyzed the dialogs that took place according to the frames of reference and the mental transformations required to produce the spatial statements. We also measured the associated mental workload. Results showed that when participants took a perspective, the manipulator’s point of view was preferred. Perspective-taking only yielded a moderate increase in mental rotations, which may explain a specifically high mental demand score for the guides’ NASA-TLX. Overall, this is in accordance with the least collaborative effort principle. This study reinforces the idea that, in collaboration, operators do not need the same aids as each other. Thus, it is not necessary to develop symmetrical tools, i.e., the same tools for all co-workers; instead, the needs of each operator should be taken into account, according to the task he has to perform. In our case, the guides would be helped with perspective-taking aids, while the manipulators would be helped with action-oriented tools.

International audience; Background: When guiding a remote collaborator in a virtual environment, people often take an addressee-perspective, which may have a high cognitive cost. In order to improve collaborative virtual environments, a better understanding of how operators share spatial information is needed.Aims: This work aimed to study the cognitive workload linked to spatial statements production in situations in which the relative positions of speaker, addressee and target were varied.Method: Twenty-two participants were asked to give - in one go - instructions to a virtual collaborator on how to find a target in a 3D environment. The scene showed an avatar in the center of eight tables. Sixty-four configurations of avatar orientation (eight possibilities) and target location (on the eight tables) were tested. We measured the delay in starting the instruction once the target appeared, the instruction duration, and the subjective evaluation of mental demand. Each instruction was classified according to the spatial reference frame used.Results: The delay was influenced by the processing of spatial information in ego-centered and addressee-centered reference frames. All subsequent measures were determined by mental transformations in addressee-centered coordinates. One condition in particular, when the target was situated diagonally behind the addressee, gave rise to a higher mental demand for the speaker, which points to the investment made by the speaker in achieving the least collaborative effort.Conclusions: Further work should seek to develop efficient tools to facilitate spatial communication in situations that induce the most mental workload.

International audience; This study addressed the question of potential disorienting effects associated to head-mounted displays, by investigating the influence of a head-fixed visual frame on the perception of the vertical when the head is tilted in the frontal plane. Subject performance in indicating the vertical was contrasted with the effect of an earth-fixed visual frame as well as with the effect of tilting the head without a frame. With the tilted frames, subjects set the rod in an intermediate direction between the gravitational vertical and the orientation of the frame. Errors were strikingly larger with a head-fixed visual frame during head tilt than with a tilted earth-based frame. The increased effect cannot be attributed to the addition of a postural effect, due to the head being tilted. Moreover, continuous vision of the frame when its orientation changed improved performance only when the head and the frame were dissociated, i.e., with an earth-based frame. Those results suggest that integrating visual information in the head-centric reference frame is crucial for spatial orientation. This property of the perceptual system should be taken into account in the design of head-mounted displays for aeronautics.

International audience; Recent studies have shown that the hand-pointing movements within arm's reach remain invariant whether the trunk is recruited or not or its motion is unexpectedly prevented. This suggests the presence of compensatory arm-trunk coordination minimizing the deflections of the hand from the intended trajectory. It has been postulated that vestibular signals elicited by the trunk motion and transmitted to the arm motor system play a major role in the compensation. One prediction of this hypothesis is that vestibular stimulation should influence arm posture and movement during reaching. It has been demonstrated that galvanic vestibular stimulation (GVS) can influence the direction of pointing movements when body motion is restrained. In the present study, we analyzed the effects of GVS on trunk-assisted pointing movements. Subjects either moved the hand to a target or maintained a steady-state posture near the target, while moving the trunk forward with the eyes closed. When GVS was applied, the final position of the hand was deviated in the lateral and sagittal direction in both tasks. This was the result of two independent effects: a deviation of the trunk trajectory and a modification of the arm position relative to the trunk. Thus, the vestibular system might be directly involved not only in the control of trunk motion but also in the arm-trunk coordination during trunk-assisted reaching movements.

International audience; This study investigated whether the tilt of the subjective vertical induced by galvanic vestibular stimulation, demonstrated by asking subjects to set a rod to the vertical, was specific to the visual modality or could be found in two tasks relying on proprioceptive and somatosensory cues. In all cases, settings were significantly deviated in the direction of the anode, but errors were smaller in the somatosensory tasks than in the visual task. We propose that the effects observed in the somatosensory modality reflects only a modification of the central representation of gravity, whereas visual effects are also in part the consequence of unregistered ocular torsion.

This paper investigated drivers’ perception during situations of loss of adherence (LOA) in static and dynamic driving simulators. The intensity and duration of the LOA were manipulated. Results show that drivers were able to correctly discriminate the different conditions of LOA in both simulators. They also highlight the importance of nonvisual information, with steering wheel haptic cues predominating for the static simulator and both the steering wheel and motion platform predominating for the dynamic simulator. This study is a first step in developing an evaluation method for electronic stability control (ESC) handling in high-performance simulator experiments. [DOI: 10.1115/1.3622752]

International audience; Current theories on the role of visuomotor coordination in driving agree that active sampling of the road by the driver informs the arm-motor system in charge of performing actions on the steering wheel. Still under debate, however, is the nature of visual cues and gaze strategies used by drivers. In particular, the tangent point hypothesis, which states that drivers look at a specific point on the inside edge line, has recently become the object of controversy. An alternative hypothesis proposes that drivers orient gaze toward the desired future path, which happens to be often situated in the vicinity of the tangent point. The present study contributed to this debate through the analyses of the distribution of gaze orientation with respect to the tangent point. The results revealed that drivers sampled the roadway in the close vicinity of the tangent point rather than the tangent point proper. This supports the idea that drivers look at the boundary of a safe trajectory envelop near the inside edge line. Furthermore, the study investigated for the first time the reciprocal influence of manual control on gaze control in the context of driving. This was achieved through the comparison of gaze behavior when drivers actively steered the vehicle or when steering was performed by an automatic controller. The results showed an increase in look-ahead fixations in the direction of the bend exit and a small but consistent reduction in the time spent looking in the area of the tangent point when steering was passive. This may be the consequence of a change in the balance between cognitive and sensorimotor anticipatory gaze strategies. It might also reflect bidirectional coordination control between the eye and arm-motor systems, which goes beyond the common assumption that the eyes lead the hands when driving.

International audience; Previous research has shown that a device called “motor priming” (MP) was more effective than other lane departure warning systems. MP prompts drivers to take action by means of small asymmetric oscillations of the steering wheel. The first objective of this experiment was to provide a deeper understanding of MP mechanisms through a series of comparisons with other haptic and auditory systems. The results suggest that much of the improvement in recovery manoeuvres observed with MP is due to the motor cue (proprioceptive preactivation of the gesture). Other factors, such as delivering the signal directly to the hands (stimulation of response effectors) or using the tactile modality rather than auditory warning, play a lesser role. This supports the hypothesis that MP devices directly intervene at the motor level, in contrast to more traditional warning systems, which only improve situation diagnosis. The second objective was to assess drivers' acceptance of the assistance devices. A dissociation between efficiency and acceptance of the devices was observed: drivers globally preferred auditory warning to MP. The combination of auditory warning and motor priming appeared to be a good compromise to achieve both effectiveness and acceptance. This experiment illustrates the relevance of simulator studies when dangerous situations are the main targets of the investigation.

International audience; This study investigated the link between drivers' gaze positioning and steering behavior when negotiating bends. This was conducted by directing the driver's point of gaze toward a target situated in the vicinity of the tangent point (TP), a region known to attract a significant amount of ocular fixations and thought to provide some useful input for anticipatory steering (M. F. Land & D. N. Lee, 1994). The orientation of gaze relative to the TP was manipulated and the resulting steering behavior was compared to that obtained with a free-gaze strategy. The data revealed that constraining eye movements did not impair steering behavior. On the contrary, the continuous tracking of the fixation point promoted smoother steering control, irrespective of the position of that point. This confirms that previewing the road curvature by tracking a distant point contributes to the stability of steering. The direction of the TP does not appear to be an essential parameter in that process (D. D. Salvucci & R. Gray, 2004). The results also indicate that continuously looking at the TP or further inside the bend yielded a deviation of the trajectory. This is consistent with the hypothesis that drivers look inside the lane boundaries to determine the future path (R. M. Wilkie & J. P. Wann, 2006).

International audience; OBJECTIVE: This paper's first objective is to determine whether motor priming assistance (consisting of directional steering wheel vibrations) can be of some benefit compared with more traditional auditory (lateralized sound) or vibratory (symmetric steering wheel oscillation) warning devices. We hypothesize that warning devices favor driving situation diagnosis, whereas motor priming can improve the initiation of action even further. Another objective is to assess the possible benefits of using multimodal information by combining auditory warning with simple steering wheel vibration or motor priming. BACKGROUND: Within the context of active safety devices, the experiment dealt with moderately intrusive driving assistance devices that intervene when a certain level of risk in terms of lane departure is reached. METHOD: An analysis of the steering behavior of 20 participants following episodes of visual occlusion was carried out. Five warning and motor priming devices were compared. RESULTS: All tested devices improved the drivers' steering performance, although their effects were modulated by the drivers' risk assessment. However, performance improvements were found to be greater with a motor priming device. No additional performance enhancement was observed when auditory warning was added to steering wheel vibration or motor priming devices. CONCLUSION: This study confirms the hypothesis that the direct intervention of motor priming at the action level is more effective than a simple warning, which intervenes upstream in situation diagnosis. Multimodal information did not seem to improve driver performance. APPLICATION: This study proposes a new kind of lateral control assistance, which acts at a sensorimotor level, in contrast with traditional warning devices.

International audience; The present study investigated the influence of eye orientation upon the experience of pain. Quasi continuous electrocutaneous stimuli which slowly increased in intensity were delivered to 32 healthy females volunteers. Participants were instructed to direct the eyes at locations that were ipsilateral or contralateral to the stimulated hand. Unpleasantness threshold and pain threshold were significantly higher when the eyes were oriented ipsilateral towards the stimulated hand. In a second experiment phase, the pain intensity increased until tolerance. There was no effect of eye orientation upon pain threshold and tolerance. Results of the first experimental part are in line with the counterintuitive idea that selective monitoring reduces pain distress. The lack of significant results in the second experiment phase is discussed in terms of statistical power and a change in coping induced by the expectation of high intensity pain.

International audience; Head-mounted displays are now extensively developed and tested to be used in enhanced reality environments. The technique consists in transmitting synthetic visual information to the user's eyes in such a way that virtual objects are superimposed on the real world. Some displays give the feeling of viewing a rectangular head-fixed virtual screen with clearly visible contours. In addition, head-mounted displays allow for the presentation of head-fixed visual information to the user and this may be an advantage in some applications, military aeronautics for instance. Presenting head-fixed visual information may not be trivial with regard to actual models of spatial orientation. This study addressed the question of potential disorienting effects associated with head-mounted displays by investigating the influence of a head-fixed visual frame on the perception of the vertical when the head or the whole body was tilted in the frontal plane. In a first experiment, subjects were instructed to indicate the vertical by rotating a visual rod that appeared at the centre of the frame whilst tilting the head in various positions. This performance was compared with the effect on the subjective vertical of a tilted earth-based visual frame without head tilts as well as with the effect of tilting the head without a frame. With the tilted frames, subjects set the rod in an intermediate direction between the gravitational vertical and the orientation of the frame. Errors were substantially larger with a head-fixed visual frame during head tilt than with a tilted earth-based frame. This difference cannot be attributed to the addition of a postural effect caused by the head being tilted Moreover, continuous vision of the frame when its orientation changed improved performance only when the head and the frame were dissociated, i.e. with an earth-based frame. A second experiment investigated the effects of a head-fixed frame on the subjective vertical and on the voluntary control of head orientation when the whole body was tilted. The effect of a head-fixed frame was contrasted with the effect of a trunk-fixed frame. Results show that the head-fixed frame modified the head behaviour when subjects were instructed to align the head with the trunk. These errors contributed to an increase in the visual frame influence on the subjective vertical. Results of both experiments suggest that integrating visual information in the head-centric reference frame is crucial for spatial orientation. This Property of the perceptual system may be relevant for the design and use of head-mounted displays.

This study puts forward a classification of driver lateral control assistance devices based on distinctions among several cooperative activities between the driver and the assistance devices. The proposed classification is based on prior work by Hoc, Young and Blosseville and Young, Stanton and Harris, who put forward related theoretical frameworks on human–machine cooperation with automation. The particular application here to lateral control allows for a human-centred categorisation of existing and potential (i.e. near-future) driver assistance devices. Four human–machine cooperation levels based on drivers' activities have been adopted. All of the proposed categories are reviewed in three steps. First, each device category is functionally defined. Next, the impact of the devices on driving behaviour is presented. A third part sums up the effectiveness of each assistance category, particularly with regard to accident data. The general conclusion synthesises the main insights for each human–machine category proposed and highlights a number of design recommendations.