- Allauch, Provence-Alpes-Cote d'Azur, France
Daniel Mestre
Aix-Marseille University, Life sciences, Faculty Member
The main objective of this study is to improve maintenance activities using mixed reality. Co-design work with Support Engineers was undertaken to develop a mixed reality solution that corresponded to the different needs of task... more
The main objective of this study is to improve maintenance activities using mixed reality. Co-design work with Support Engineers was undertaken to develop a mixed reality solution that corresponded to the different needs of task sequencing feasibility. Multiple versions of the solution were tested using Microsoft HoloLens hardware to achieve continuous improvement. The study compared the two latest versions of the solution: the CAD version and the PHYS version. The CAD version was an immersive version inspired by CATIA CAD software, while the PHYS version implemented a realistic approach to parts handling (including gravity, continuous presence, and spatial organization of physical parts on a real table). Support Engineers carried out an experiment, performing a disassembly/assembly task using both versions of the solution. Results showed that the overall workload was significantly reduced, along with task completion time, using the PHYS solution. The PHYS version was also judged to be more usable than the CAD version. Adding 'pseudo-natural' manipulation of virtual objects to a maintenance task simulation better suits the needs of Support Engineers.
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A great deal of research today is concerned with the study of the cognitive processes involved in the realization of spatial displacements. In this article, we will analyze how the introduction of interfaces affects the conditions in... more
A great deal of research today is concerned with the study of the cognitive processes involved in the realization of spatial displacements. In this article, we will analyze how the introduction of interfaces affects the conditions in which a displacement is produced and controlled. We will attempt to show that as the situation becomes less and less natural, the already important role played by visual information increases and the ways in which visual information is presented on the interfaces change as the modalities increase in number. Our discussion will not only be supported by fundamental and applied research on the mental representation of space and the visual control of displacement, but also by the few available studies on tele-operated situations.
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Research Interests: Computer Science, Computer Graphics, Computational Modeling, Information Visualization, Automata, and 15 moreCellular Automata, Theoretical Computer Science, Information Visualisation, Boolean Algebra, Proceedings, Data Visualisation, Gpu programming, Real Time, Computer Graphic, Encoding, Emergent Behavior, Higher Dimensions, Multi Dimensional, Multidimensional Systems, and Cellular automaton
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Research Interests: Computer Science, Parallel Computing, Visualization, Rendering (Computer Graphics), Computational Science, and 15 moreCellular Automata, Digital imaging, Real-time rendering, OPERATING SYSTEM, Information Flow, Computation, Graphics, Real Time, Grid, Emergent Behavior, Large Data Sets, Cellular automaton, Graphics processing unit, Springer Ebooks, and Graphics processor unit
We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback,... more
We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback, VR feedback and VR feedback with the presence of a virtual coach, acting as a pacer. In VR feedback conditions, we observed a decreased level of perceived exertion and an increased level of enjoyment of physical activity, when compared to a regular exercise situation (no VR feedback). We also observed a shift in the subjects' attentional focus, from association (in the absence of VR feedback) to dissociation (in VR feedback conditions). Moreover, the presence of a virtual coach in the VR environment triggered a systematic regulation of the (virtual) displacement speed, whose relationship with perceived enjoyment and exertion require further work.
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The present work highlights current developments and an ongoing experimental evaluation of how a tablet PC can effectively act as an interaction device for 3D manipulation tasks. More specifically, we focused on a 3D docking task. This... more
The present work highlights current developments and an ongoing experimental evaluation of how a tablet PC can effectively act as an interaction device for 3D manipulation tasks. More specifically, we focused on a 3D docking task. This collaborative project was conducted within the Visionair European project. The goal was to design a versatile interface that was independent of the targeted VR system (from 2D screens to CAVE-like systems). We investigated the usability of tactile (i.e. finger-controlled) tablets that are omnipresent in our daily life, assumed to have intuitive control characteristics and easily connected to a VR system (via WIFI connections). Participants' performance was evaluated when using a tablet, as compared to a classical mouse interface. Results indicated comparable learning effects (with task repetition) for both devices, but a clear advantage of the tablet's interface, as concerns the simultaneous use of multiple degrees of freedom of motion of the manipulated object.
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ABSTRACT The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring... more
ABSTRACT The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring "presence" to use it as a measure for ecological validity in driving simulators. The underlying assumption is that a person experiencing a strong sense of presence in the virtual environment will react in this environment as if it would be a real one. We propose to measure "presence" by measuring "attention" toward the driving task". Our objective is to demonstrate that the higher the subject's attention required by the primary driving task will be, the more the spatial presence will be felt. In the experiment we tried to vary "attention" by adding a dual task and by adding traffic and measure driving performance and subjective "presence" (MEC-SPQ; Measurement, Effects, Conditions-Spatial Presence Questionnaire). The main result is a lack of congruence between subjective and behavioral measures.
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Research Interests: Computer Science, Artificial Intelligence, Computer Vision, Eye tracking, Attention, and 15 moreMotion perception, Medicine, Optical Flow, Humans, Depth Perception, Optic Flow, Eye Movements, Optical Illusions, Adult, Eye Movement, Parallax, Motion Parallax, Binocular Disparity, Optokinetic Nystagmus, and Medical and Health Sciences
Research Interests: Computer Science, Perception, Cave, Virtual Reality, Geometry, and 4 moreOptic Flow, Scale, Tunnel, and Odometry
Virtual Reality (VR) leads to realistic experimental situations, while enabling researchers to have deterministic control on these situations, and to precisely measure participants' behavior. However, because more realistic and... more
Virtual Reality (VR) leads to realistic experimental situations, while enabling researchers to have deterministic control on these situations, and to precisely measure participants' behavior. However, because more realistic and complex situations can be implemented, important questions arise, concerning the validity and representativeness of the observed behavior, with reference to a real situation. One example is the investigation of a critical (virtually dangerous) situation, in which the participant knows that no actual threat is present in the simulated situation, and might thus exhibit a behavioral response that is far from reality. This poses serious problems, for instance in training situations, in terms of transfer of learning to a real situation. Facing this difficult question, it seems necessary to study the relationships between three factors: immersion (physical realism), presence (psychological realism) and behavior. We propose a conceptual framework, in which presence is a necessary condition for the emergence of a behavior that is representative of what is observed in real conditions. Presence itself depends not only on physical immersive characteristics of the Virtual Reality setup, but also on contextual and psychological factors.
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In everyday life, humans and most animals need to navigate in their environment, which produces multiple sources of perceptual information, such as locomotor cues (i.e. proprioceptive, efference copy and vestibular cues) and optic flow.... more
In everyday life, humans and most animals need to navigate in their environment, which produces multiple sources of perceptual information, such as locomotor cues (i.e. proprioceptive, efference copy and vestibular cues) and optic flow. However, few studies focused on the role of the visual consequences of walking (bob, sway, and lunge head motion) on self-motion perception. In a previous study, in which static observers were confronted to a visual simulation of forward motion, we have shown that adding rhythmical components to an optic flow pattern improved the accuracy of subjects' travelled distance estimations, in comparison with a purely translational flow. These results were attributable to the fact that oscillations may increase the global retinal motion and thus improve vection. Another hypothesis was that, walking step frequency being a significant cue in speed perception, visual consequences of step frequency might be at the origin of better estimations.To test this, we used the same experimental procedure in which observers, immersed inside a 4-sided CAVE, had to indicate when they thought they had reached a previously seen target. We tested whether different oscillation frequencies would affect the perception of distance travelled. Observers were confronted with 4 conditions of optic flows simulating forward self-motion. The first condition was generated by purely translational optic flow, at constant speed. The three other conditions of flows were vertical triangular oscillations with three kinds of frequencies added to linear forward motion, at the same forward speed. Results show that two groups can be distinguished. Regarding the first group, as in the previous study, adding rhythmic components improves the perception of distance travelled. For the second group, the higher the frequency, the earlier the answers, suggesting that these subjects related the oscillation frequency to their step frequency and perceived themselves as moving faster.
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Visual motion perception plays a fundamental role in vehicle guidance. For example, the control of one's trajectory is mainly performed on the basis of visual information about the characteristics of the trajectory and about the... more
Visual motion perception plays a fundamental role in vehicle guidance. For example, the control of one's trajectory is mainly performed on the basis of visual information about the characteristics of the trajectory and about the spatial layout. In particular, the pattern of optical flow resulting from the observer's self-motion through a stable environment is used by the subject to obtain information about his direction or speed of self-motion. However, little is known about the twofold task of a driver approaching an intersection, where he/she must control both his/her trajectory and detect the motion of other vehicles. In the present experiment, the perceptual ability of observers in relation to their level of driving expertise was evaluated. For the covering abstract, see IRRD 892069.
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... Title: PERCEPTION OF A MOVING VEHICLE WHEN APPROACHING AN INTERSECTION. ... 773D: AMSTERDAM; NEW YORK: NORTH-HOLLAND; NEW YORK, NY, USA: SOLE DISTRIBUTORS FOR THE USA AND CANADA, ELSEVIER SCIENCE PUB. CO., 1991. ...
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During self-motion, the driver's visual anticipation of the trajectory of another moving vehicle relies both on the global optical flow motion resulting from his/her self-motion and on local visual cues, such as the vehicle's... more
During self-motion, the driver's visual anticipation of the trajectory of another moving vehicle relies both on the global optical flow motion resulting from his/her self-motion and on local visual cues, such as the vehicle's optical trajectory and the relative optical motion between the vehicle and fixed elements in the environment. Here, we hypothesised that the complexity of the environment and the drivers' perceptual style influenced the use of such predictive visual information. Graphics displays simulated a driver's curvilinear movement towards an intersection where another vehicle was arriving. Subjects had to decide whether this vehicle would reach the intersection before or after them. Response times and differential thresholds were analysed. Overall, subjects' judgements were more accurate with realistic environments and with a road-sign near the intersection. Moreover, field-independent subjects were better than field-dependent subjects with realistic scenes, suggesting that they are better at picking up dynamic relevant information in a complex environment. For the covering abstract see IRRD E102207.
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AN EXPERIMENT IS REPORTED IN WHICH COMPUTERIZED CAR DRIVING SIMULATIONS WERE USED TO MANIPULATE ENVIRONMENT CHARACTERISTICS AND VEHICLES' TRAJECTORIES. VISUAL DISPLAYS SIMULATED THE CURVILINEAR APPROACH OF AN OBSERVER TO AN... more
AN EXPERIMENT IS REPORTED IN WHICH COMPUTERIZED CAR DRIVING SIMULATIONS WERE USED TO MANIPULATE ENVIRONMENT CHARACTERISTICS AND VEHICLES' TRAJECTORIES. VISUAL DISPLAYS SIMULATED THE CURVILINEAR APPROACH OF AN OBSERVER TO AN INTERSECTION. AN APPROACHING VEHICLE, COMING FROM THE RIGHT OF THE CURVED ROAD, WAS PROGRAMMED TO REACH THIS INTERSECTION EITHER 1 SECOND BEFORE OR AFTER THE OBSERVER. VISUAL DISPLAYS PROJECTED ON A TV MONITOR OR ON A LARGE SCREEN WERE STOPPED 2 SECONDS BEFORE THE OBSERVER REACHED THE INTERSECTION. SUBJECTS HAD TO DECIDE WHETHER THEY WOULD HAVE REACHED THE INTERSECTION BEFORE, AFTER OR AT THE SAME TIME AS THE APPROACHING VEHICLE. OVERALL, RESPONSES WERE CORRECT IN 62% OF CASES. A SPATIAL REFERENCE POINT (ROAD SIGN) NEAR THE INTERSECTION IMPROVED PERFORMANCE. HOWEVER, JUDGMENTS BECAME INCREASINGLY DIFFICULT FOR SMALL CURVATURE RADII WHERE RELATIVE VISUAL MOTION BECOMES AMBIGUOUS. MOREOVER, SUBJECTS APPEARED TO RELY MORE ON LOCAL VISUAL CUES WHEN VISUAL INFORMATION WAS PRESENTED ON A TV MONITOR, AND ON GLOBAL VISUAL CUES WHEN A LARGE-SCREEN DISPLAY WAS USED. (A) FOR THE COVERING ABSTRACT OF THE CONFERENCE SEE IRRD 858984.
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Research Interests: Information Systems, Engineering, Psychology, Cognitive Science, Computer Science, and 15 moreCyberpsychology, Psychotherapy, Depression, Video Games, Quality of life, Medicine, Virtual Reality, Humans, Female, Male, Follow-up studies, Computer User Interface Design, Questionnaires, Adult, and Phobic disorders
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Magnetic Confinement Fusion machines called tokamak (e.g. ITER and WEST projects), as well as many industrial projects, require a high integration level in a confined volume. The feasibility of installation and maintenance by an operator... more
Magnetic Confinement Fusion machines called tokamak (e.g. ITER and WEST projects), as well as many industrial projects, require a high integration level in a confined volume. The feasibility of installation and maintenance by an operator has to be considered in the early stages of the design. Virtual reality technologies have opened new perspectives and solutions to take into account assembly and maintenance constraints, using virtual mock-ups. In our applications, the human factor takes an important role. Since the operator interacts in a very tight and confined environment, he has to pay attention to his whole body relative to the virtual environment, in the absence of haptic feedback. In this context, enriched sensorial information, called "collision awareness feedback", must be defined, to favour an appropriate operator's spatial behavior with respect to the environment. In this paper, we present a preliminary study, testing the effect of vibrotactile feedback in a simple tracking task, compared to a pure visual feedback.
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The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring “presence” to... more
The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring “presence” to use it as a measure for ecological validity in driving simulators. In this way, the purpose of this study is especially to investigate the relationship between subjective ratings of presence and physiological responses in virtual driving environments. Six driving scenarios were, thus, created, resulting from crossing two independent variables, i.e., the visual realism of the virtual environment (three virtual environments were created ranging from very realistic to not realistic) and the degree of visibility on the road for each virtual environment (two conditions were proposed : very good visibility and very bad visibility). Whatever the scenario, the driving task was always to follow a red car without losing sight of its location. To measure subjective presence, attention and emotional involvement, Presence, and Mood questionnaires were used. As measures of physiological response, heart rate and skin conductance level were acquired and more specifically the heart rate variability (HRV) was calculated from the acquired ECG data. Driving performance (standard deviations of speed and lateral position) was also analyzed. Fourteen participants (25.4±4.5 years of age) were placed in a fixed base driving simulator and performed consecutively the six driving scenarios in a different order. The results show correlations between Presence Questionnaire scores and both HRV parameters (time and frequency domains) and skin conductance level. In the study, HRV parameters and skin conductance level appeared to indicate the participant's degree of presence.
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Nuclear maintenance operations require several types of cognitive and motor skills that can be trained in immersive environments. However, there is a lack of normalized methodological approaches to classify tasks and guide them for a... more
Nuclear maintenance operations require several types of cognitive and motor skills that can be trained in immersive environments. However, there is a lack of normalized methodological approaches to classify tasks and guide them for a potential transposition to immersive training. This paper proposes a methodological approach to classify nuclear maintenance tasks based on their complexity and the potential transfer of training obtainable from each type of immersion techniques and their related interactions.This proposed methodology provides a novel approach to compare various immersive technologies and interactions in a normalized way for a same industrial task.This paper aims at serving as a base for a methodological guide dedicated to the transposition of nuclear maintenance skills learned in immersive environments to real environment setups and proposes two future use cases based on this methodological approach.
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More than 1.3 million people lose their lives every year in traffic accidents. Improving road safety requires designing better vehicles and investigating drivers’ abilities more closely. Driving simulators are constantly being used for... more
More than 1.3 million people lose their lives every year in traffic accidents. Improving road safety requires designing better vehicles and investigating drivers’ abilities more closely. Driving simulators are constantly being used for this purpose, but the question which often arises as to their validity tends to be a barrier to developments in this field. Here we studied the validity of a simulator, defined as how closely users’ behavior under simulated conditions resembles their behavior on the road, based on the concept of drivers’ feeling of presence. For this purpose, the driving behavior, physiological state and declarative data of 41 drivers were tested in the Sherpa2 simulator and in a real vehicle on a track while driving at a constant speed. During each trial, drivers had to cope with an unexpected hazardous event (a one-meter diameter gym ball crossing the road right in front of the vehicle), which occurred twice. During the speed-maintenance task, the simulator showed a...
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L’approche bionique, consistant a donner des proprietes des etres vivants a un robot, est un moyen de diminuer efficacement l’ecart existant entre le fonctionnement d’un operateur humain et d’une machine. Dans cette etude, le comportement... more
L’approche bionique, consistant a donner des proprietes des etres vivants a un robot, est un moyen de diminuer efficacement l’ecart existant entre le fonctionnement d’un operateur humain et d’une machine. Dans cette etude, le comportement d’anticipation visuo-motrice observe chez l’homme lors du controle des deplacements a ete implemente sur une base mobile teleoperee. Cette implementation a ete effectuee suivant deux modes de couplage : orientation de camera asservie a la direction du deplacement (modele “ plate-forme ”) ou bien, direction du deplacement asservie a l’orientation de la camera (modele “ camera ”). Les resultats montrent 1 / qu’un teleoperateur est plus performant lorsqu’il pilote un vehicule pourvu d’anticipation et 2 / que cet avantage est d’autant plus marque suivant le modele “ camera ”. Cela confirme que la cooperation homme-machine beneficie de l’implantation sur l’engin teleopere de modes de couplages visuo-moteurs proches de ceux de l’operateur.
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SUMMARY IMPLEMENTATION OF VISUO-MOTOR ANTICIPATORY SCHEMES IN TEILOPERATION A major issue in teleoperation is to try to reduce the gap that exists between the functioning of the human operator and that of the machine. The bionic approach,... more
SUMMARY IMPLEMENTATION OF VISUO-MOTOR ANTICIPATORY SCHEMES IN TEILOPERATION A major issue in teleoperation is to try to reduce the gap that exists between the functioning of the human operator and that of the machine. The bionic approach, which consists of giving human properties to robots, is effectively a means of reducing the natural differences between the modes of functioning of these two entities, biological and mechanical. In the experimental study presented here, we implemented the visuo-motor anticipatory behaviour observed in locomoting humans using a teleoperated mobile robot. The ecological validity of such an implementation was empirically tested using a slalom route task, with independent experimental groups : the first one piloting a robot equipped with a camera that visually anticipated movement and the other one piloting a robot with a fixed camera. This « human-like » behaviour was also implemented using two different coupling modes. In the first mode, the orientation of the camera (on board the robot) was dependant on the direction of displacement of the robot, the operator controlling the latter (base mode). In the second mode, the direction of displacement was defined by the orientation of the camera, which was manipulated by the operator (camera mode). Experimental results show : 1 I that the operator is more efficient and seems much more at ease when a visuo-motor anticipatory scheme is implemented on the teleoperated device and 2 I that this effect is more pronounced in the camera mode. These results suggest that there is a case for introducing sensori-motor anticipatory « human-like » behaviour into artificial partially-automated teleoperated systems.
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Research Interests: Physics, Optics, Nonlinear dynamics, Motion perception, Medicine, and 15 moreTemporal dynamics, Humans, Reaction Time, Eye Movements, Time Factors, Eye Movement, Grating, Amplitude, Aperture Problem, Motion Integration, Psychomotor Performance, Neuropsychological Tests, photic stimulation, Psychology and Cognitive Sciences, and Medical and Health Sciences
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Magnetic Confinement Fusion machines called tokamak (e.g. ITER and WEST projects), as well as many industrial projects, require a high integration level in a confined volume. The feasibility of installation and maintenance by an operator... more
Magnetic Confinement Fusion machines called tokamak (e.g. ITER and WEST projects), as well as many industrial projects, require a high integration level in a confined volume. The feasibility of installation and maintenance by an operator has to be considered in the early stages of the design. Virtual reality technologies have opened new perspectives and solutions to take into account assembly and maintenance constraints, using virtual mock-ups. In our applications, the human factor takes an important role. Since the operator interacts in a very tight and confined environment, he has to pay attention to his whole body relative to the virtual environment, in the absence of haptic feedback. In this context, enriched sensorial information, called "collision awareness feedback", must be defined, to favour an appropriate operator's spatial behavior with respect to the environment. In this paper, we present a preliminary study, testing the effect of vibrotactile feedback in a simple tracking task, compared to a pure visual feedback.
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Les collisions en intersection representent de 40 a 50 pour cent des accidents de la route. Le comportement perceptif du conducteur est l'element cle de la comprehension de ces accidents. Il semble que l'anticipation de collisions... more
Les collisions en intersection representent de 40 a 50 pour cent des accidents de la route. Le comportement perceptif du conducteur est l'element cle de la comprehension de ces accidents. Il semble que l'anticipation de collisions fait egalement appel a des capacites perceptives definies par exemple par un style perceptif, la dependance-independance a l'egard du champ. Les resultats montrent que les independants ont des estimations plus precises en environnement routier plus complexe et semblent mieux integrer la reference spatiale (panneau) dans leur analyse perceptive que ceux dependants a l'egard du champ. Dans une perspective ergonomique, une telle demonstration devrait trouver des applications en termes d'amenagement de l'environnement routier.(A)
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Processing of motion parallax relies on the ability of the visual system to segregate locally different motion signals and integrate them over space and time in order to reconstruct a 3-D structure. In a series of experiments, we... more
Processing of motion parallax relies on the ability of the visual system to segregate locally different motion signals and integrate them over space and time in order to reconstruct a 3-D structure. In a series of experiments, we evaluated the thresholds for differential motion detection and their dependences upon the spatial structure of the optic-flow field. Visual stimuli were large moving random-dot displays (80 deg × 60 deg). Each dot was randomly attributed one of two velocities whose difference ranged between 0% and 80% of their average velocity, which ranged between 2 and 64 deg s−1. Stimulus duration was from 130 to 1040 ms. Subjects were instructed to stare at a central fixation mark and had to decide whether the display specified one or two surfaces. At a duration of 130 ms, subjects needed more than 40% difference between the two velocities to reach a 75%-correct detection criterion. Thresholds reached a minimum value of about 20% at a duration of 500 ms. Thresholds alwa...
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An experimentation was carried out to test the role of global and local visual information on the visual anticipation of a collision. We simulated a driver's approach to an intersection where another vehicle was arriving This vehicle... more
An experimentation was carried out to test the role of global and local visual information on the visual anticipation of a collision. We simulated a driver's approach to an intersection where another vehicle was arriving This vehicle could reach the intersection 1000 msec, 500 msec or 200 msec before or after the driver. The road surface (uniform or textured) and environmental cues (delineation lines) were manipulated. Subjects had to anticipate, by pressing as quickly as possible one of the two buttons placed on the vehicle's wheel, whether the other vehicle would arrive before of after them at the intersection. Results show that the visual anticipation of a collision depends on various visual cues included in the road environment, such as the road texture or delineation lines. They are consistent with previous findings that showed that the sensation of self-motion is increased by the presence of a structured environment.
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The aim of this experiment was to determine the kind of visual information used in anticipating rear-end collisions according to the visual information available in the road environment and the perceptual style of the driver. Nine field... more
The aim of this experiment was to determine the kind of visual information used in anticipating rear-end collisions according to the visual information available in the road environment and the perceptual style of the driver. Nine field independent and seven field dependent subjects had to judge time-to-collision under various visual and spatio-temporal conditions. Results showed that only under poor visual conditions (presence of the obstacle alone) were temporal estimates affected by approach speed, obstacle distance and actual time-to-collision. Under these conditions the estimates appeared to be mainly based on static depth cues (angular size). The enrichment of the visual scene (texture) allowed the processing of motion-based information (optical flow) and made the estimates independent of spatio-temporal conditions; variability, overshoots and subjective difficulty were reduced. Whereas both field-dependent and independent observers took global visual changes into account, only field-independent subjects were able to use local motion as well. The findings suggest that multiple sources of information play a part in time-to-collision judgements. For the covering abstract see IRRD E102207.
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A fundamental aspect in driving is predicting critical events in the near future. A driver on a collision course, for example, has to accurately evaluate how close s/he is to the impending collision in order to brake or swerve at the... more
A fundamental aspect in driving is predicting critical events in the near future. A driver on a collision course, for example, has to accurately evaluate how close s/he is to the impending collision in order to brake or swerve at the right time. In other words, s/he has to judge time-to-collision (TTC), which refers to the time that remains before reaching an obstacle, and thus to the time available for taking action. TTC is considered to be a crucial parameter in controlling avoidance behaviour. TTC is also likely to be involved in more complex judgement tasks such as overtaking or left-turn manoeuvres, where the driver has to determine whether there is enough time for the planned action. The underlying concept of temporal action control is being used increasingly often in the study of driving behaviour, which addresses the anticipatory aspects of actions such as braking, trajectory control, car following, traffic merging decisions, curve taking, stop-or-go decisions at intersectio...
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The paper presents an initial framework for studyin g issues in the design and evaluation of Collaborative Virtual Envi ronments based on immersive projection technology systems. T he framework consists of a software platform, develope d... more
The paper presents an initial framework for studyin g issues in the design and evaluation of Collaborative Virtual Envi ronments based on immersive projection technology systems. T he framework consists of a software platform, develope d using Virtools® software suite, which supports collaborat ive work among collaborators in different immersive systems (CAVE®like environment, Workbench, etc.), and usability i nspection of each iteration of the platform. The objective of th is setting for the framework was to gain insights on both technologica l aspects regarding the development of such a platform and hu man factors issues on collaborative work within Virtual Environ ments; and more importantly on the interrelation between techn ological and human factors aspects for building usable Collabora tive Virtual Environments. A live demonstration of the platform connecting two CAVE®-like environments situated in geographica lly distant places was organized to collect feedback from parti ci...
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Une simulation interactive du controle visuel du deplacement a permis d'etudier les parametres de la scene visuelle qui sont traites par le sujet humain en mouvement dans un grand espace. A partir des aspects statiques de la... more
Une simulation interactive du controle visuel du deplacement a permis d'etudier les parametres de la scene visuelle qui sont traites par le sujet humain en mouvement dans un grand espace. A partir des aspects statiques de la stimulation visuelle, on a mis en evidence le role positif joue par la representation de caracteristiques dynamiques des mouvements de rotation et de translation de l'observateur. Les resultats des travaux presentes suggerent que le controle des proprietes spatiales du deplacement, telles que la stabilite et la position d'une trajectoire, peut etre realise par la perception des transformations de la scene visuelle. Le traitement de l'information visuelle semble cependant etre conditionne par l'existence de presupposes cognitifs, tels que la rigidite de l'environnement et la presence d'un plan porteur. Les implications de cette recherche pour l'elaboration d'aides visuelles au deplacement sont discutees.
L'anticipation visuelle du mouvement d'un autre vehicule par le conducteur qui approche une intersection est liee a la fois au flux optique global provoque par le deplacement du conducteur mais aussi a des indications locales,... more
L'anticipation visuelle du mouvement d'un autre vehicule par le conducteur qui approche une intersection est liee a la fois au flux optique global provoque par le deplacement du conducteur mais aussi a des indications locales, telles que le mouvement visuel de l'autre vehicule ou/et les mouvements visuels relatifs entre l'autre vehicule et les elements fixes de l'environnement. Ici, deux experimentations analysent les capacites des conducteurs a faire de telles anticipations en fonction de leur experience en conduite et de leur niveau de dependance/independance a l'egard du champ visuel. Les resultats suggerent que l'experience de la conduite met en jeu des aspects temporels des processus de traitement de l'information visuelle alors que la dependance/independance a l'egard du champ est liee a une habilete a saisir l'information visuelle pertinente dans un environnement complexe.(A)
Abstract The development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are... more
Abstract The development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed in parallel and we must consider integration, assembly and maintenance issues, which might have a huge impact on the overall design. That also implies to consider the operator’s feedback to assess the feasibility of accessibility or maintenance processes. Virtual reality (VR) provides tools to optimize such integration. In 2010, the CEA IRFM decided to upgrade its design tools, by using VR during the life cycle (from design to operations) of a fusion component. The VR platform is intensively used in the design and assembly studies of WEST components. In particular, feasibility of the assembly scenario is assessed by the operators involving in the real assembly work. To study this aspect, the use of static manikins is quite frequent in the industry. However, more complex studies, like the feasibility of assembly and maintenance tasks in complex and very confined environments, require enhanced features such as dynamic and biomechanically realistic virtual humans. We also study the contribution of tactile feedback to improve physical presence and interaction in the virtual environment (VE), which is very important for the validation of a given task’s feasibility and the ergonomic evaluation of the posture and gesture of the operator. In particular, we show that adapted behavior in respect to physical elements of the VE can be obtained using a dynamic co-localized representation of the subject’s body and a pseudo-haptic tactile feedback. In this paper, we present integration studies involving operators and recent advances in the assessment of maintenance feasibility.
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We previously demonstrated that behavioral adjustments to environmental properties constituted an objective indicator of presence in Virtual Reality VR. The subject's task was to walk through virtual apertures of variable width.... more
We previously demonstrated that behavioral adjustments to environmental properties constituted an objective indicator of presence in Virtual Reality VR. The subject's task was to walk through virtual apertures of variable width. Subjects exhibited a behavioral transition, from frontal walking to body rotation, while walking from broad to narrow apertures. Here, we tested the same basic protocol, using a Head-Mounted Display HMD. Overall, results show the same basic behavior shoulder rotation through a narrow door. However, optimal adaptive behavior avoiding collision with the door's borders required both the presence of a dynamic representation of the subject's body in the visual display and of a vibrotactile feedback, signaling approach of the subject's shoulder towards the doorpost.
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When static observers are exposed to a visual simulation of forward self-motion, they generally overestimate travelled distance relative to a previously seen distant target (Redlick, Harris, & Jenkin, 2001). Using the same... more
When static observers are exposed to a visual simulation of forward self-motion, they generally overestimate travelled distance relative to a previously seen distant target (Redlick, Harris, & Jenkin, 2001). Using the same experimental paradigm, we reproduced this result, which can be accounted for by a "leaky path integration" model (Lappe, Jenkin, & Harris, 2007). However, we also showed that a translational optical flow with "biological" additional oscillatory components, simulating head motion during natural walking, allows for better perception of travelled distance, as compared to a purely translational flow. This result can be discussed as an improvement of path integration, using an "ecological" optic flow pattern (close to "natural walking" feedback). In a subsequent experiment, we tested if it is the biological or the rhythmical nature of the simulation which provides better estimates of travelled distance. Participants were standing and passively confronted to three conditions of virtual simulation of self-motion in a 4-sided CAVE: (1) a translational optical flow (2) a translational flow, with an added rhythmic component, via "triangular" oscillations in the vertical axis and (3) a "biological" flow, reproducing natural motion of the head during walking, as previously measured and modelled using a motion capture system. The results confirm that the addition of rhythmical components in the optic flow pattern improve the accuracy of travelled distance. However, they failed to reveal a significant difference between "biological" and "rhythmic" oscillations. Further experiments on the effect of spatio-temporal oscillatory components in the optical flow are required. However, these results can be related to recent studies comparing the effect of smooth and "jittering" optic flows on vection onset and strength (Palmisano et al., 2014). One suggestion is that oscillatory components produce a non-monotonous pattern of retinal motion, maintaining optimal sensitivity to optic flow, and consequently improving the perception of travelled distance. Meeting abstract presented at VSS 2016
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The paper aims at presenting the Acorformed corpus composed of human-human and human-machine interactions in French in the specific context of training doctors to break bad news to patients. In the context of human-human interaction, an... more
The paper aims at presenting the Acorformed corpus composed of human-human and human-machine interactions in French in the specific context of training doctors to break bad news to patients. In the context of human-human interaction, an audiovisual corpus of interactions between doctors and actors playing the role of patients during real training sessions in French medical institutions have been collected and annotated. This corpus has been exploited to develop a platform to train doctors to break bad news with a virtual patient. The platform has been exploited to collect a corpus of human-virtual patient interactions annotated semi-automatically and collected in different virtual reality environments with different degree of immersion (PC, virtual reality headset and virtual reality room).
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Il est a present bien admis que le flux optique, decrivant les transformations de la scene visuelle d'un observateur en deplacement, est utile au controle de la trajectoire d'un vehicule. Il reste neanmoins a mieux decrire... more
Il est a present bien admis que le flux optique, decrivant les transformations de la scene visuelle d'un observateur en deplacement, est utile au controle de la trajectoire d'un vehicule. Il reste neanmoins a mieux decrire l'information visuelle qui est reellement utilisee par le conducteur. Je propose ici une approche experimentale de ce probleme, qui permet notamment d'etudier la qualite de la perception de son propre deplacement, en fonction de la direction du regard de l'observateur. Applique a des cas concrets de projets d'amenagement routier, ce type de methodologie peut contribuer a l'optimisation de la securite routiere, du point de vue de l'implication des facteurs perceptifs humains.
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Nous presentons dans cet article la synthese d'un projet cooperatif qui a regroupe une equipe de cliniciens hospitaliers et trois equipes de chercheurs du CNRS et de l'Universite, et destine a tester une nouvelle hypothese... more
Nous presentons dans cet article la synthese d'un projet cooperatif qui a regroupe une equipe de cliniciens hospitaliers et trois equipes de chercheurs du CNRS et de l'Universite, et destine a tester une nouvelle hypothese unificatrice dans l'autisme. La question etait de savoir si les troubles communicatifs et relationnels typiques de l'autisme sont correles a des troubles du traitement temporel des evenements sensoriels et moteurs. Des enfants et adolescents autistes ont ete testes dans trois types de tâches experimentales visant a tester i) la vision du mouvement, ii) la perception categorielle de phonemes et iii) l'anticipation motrice. Les resultats montrent que dans chacun de ces trois domaines, les performances des sujets autistes sont limitees par rapport a celles des sujets temoins, et temoignent d'une difficulte a traiter les evenements sensoriels et produire des evenements moteurs en temps reel. Cette difficulte pourrait rendre compte des anomalies...
Keywords: Anxiety ; Emotion ; Affect ; Locomotion ; Virtual reality Reference EPFL-CONF-164430 Record created on 2011-03-23, modified on 2016-08-09
It is a well known fact that visual information is a powerful basis for the control of self-motion. Any movement of the observer in three dimensional space generates an optical inflow, consisting of the apparent movement of elements in... more
It is a well known fact that visual information is a powerful basis for the control of self-motion. Any movement of the observer in three dimensional space generates an optical inflow, consisting of the apparent movement of elements in the observer’s visual field. In most cases, this optical flow depends on the observer’s movements (of the body, head and eyes) and on the structure of the space involved. In this paper, the authors have shown how the combination of the rotational and transitional movements of the observer, made when driving a car, can generate complex optic flow. The usefulness of such optic flow in the control of self-motion could then depend on proprioceptive (extra-visual) information which would be necessary for the disassociation of the transitional and rotational components of the optic flow.
In this paper, we propose a new approach of the behavioral validity’s assessment of driving simulators. Our ambition is to find a way of measuring “presence” to use it as a measure for ecological validity in driving simulators. The... more
In this paper, we propose a new approach of the behavioral validity’s assessment of driving simulators. Our ambition is to find a way of measuring “presence” to use it as a measure for ecological validity in driving simulators. The underlying assumption is that a person experiencing a strong sense of presence in the virtual environment will react in this environment as if it would be a real one. We propose to measure "presence" by measuring “attention” toward the driving task". Our objective is to demonstrate that the higher the subject's attention required by the primary driving task will be, the more the spatial presence will be felt. In the experiment, we tried to vary "attention" by adding a dual task and by adding traffic and measure driving performance and subjective "presence" (MEC-SPQ: Measurement, Effects, Conditions-Spatial Presence Questionnaire). The main result is a lack of congruence between subjective and behavioral measures. Key...
The development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed... more
The development of fusion plants is more and more challenging. Compared to previous fusion experimental devices, integration constraints, maintenance and safety requirements are key parameters in the ITER project. Components are designed in parallel and we must consider integration, assembly and maintenance issues, which might have a huge impact on the overall design. That also implies to consider the operator's feedback to assess the feasibility of accessibility or maintenance processes. Virtual reality (VR) provides tools to optimize such integration. In 2010, the CEA IRFM decided to upgrade its design tools, by using VR during the life cycle (from design to operation) of a fusion component. The VR platform is intensively used in the design and assembly studies of WEST components. In particular, feasibility of the assembly scenario is assessed by the operators involving in the real assembly work. To study this aspect, the use of static manikins is quite frequent in the industr...
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When exploring their environment, humans and other animals have the ability to use many sources of information to estimate the distance they travel. Several studies have shown that optic flow is a significant cue to perceive distance... more
When exploring their environment, humans and other animals have the ability to use many sources of information to estimate the distance they travel. Several studies have shown that optic flow is a significant cue to perceive distance travelled. Furthermore, it was found that adding various viewpoint oscillations to a purely translational optic flow, simulating forward self-motion, modulated this perception. In a series of experiments, we tested whether the perception of distance travelled was also affected by viewpoint oscillation, similar to head motion during natural walking. A first series of experiments, participants were exposed to an immersive optic flow simulating forward self-motion and they were asked to indicate when they thought they had reached the remembered position of a previously seen target. The main conclusion from these experiments is that viewpoint oscillations improve the perception of distance travelled. Moreover, this effect appears to be linked to an increase in global retinal motion. However, the "ecological" contribution cannot be ruled out. Manipulating different viewpoint oscillation frequencies showed that the optimal performance was observed for a range of frequencies close to that observed for the head motion during natural walking. Two further experiments aimed to test whether the idiosyncrasy of viewpoint oscillations affects the perception of distance travelled in stationary observers and whether the absence of their own viewpoint oscillation played an important role in subjects' estimates, while they were walking on a treadmill. And finally, in a last experiment we tried to develop a dynamic measure of distance travelled to a previously seen target, with a continuous pointing task method. Overall, our results show that viewpoint oscillations play an important role in visual self-motion perception and that several parameters (including visual information, proprioceptive information and ecological aspects of natural walking) seem to be involved in this process.
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Driving experiments in real conditions are considered as a ‘gold standard’ to evaluate the effects of drugs on driving performance. Several constraints are difficult to manage in these conditions, so driving simulation appears as the best... more
Driving experiments in real conditions are considered as a ‘gold standard’ to evaluate the effects of drugs on driving performance. Several constraints are difficult to manage in these conditions, so driving simulation appears as the best alternative. A preliminary comparison is crucial before being able to use driving simulation as a valid evaluation method. The aim of this study was to design a driving simulation method for assessing drug effects on driving. We used cannabis (THC) as a positive control and assessed whether THC affects driving performance in simulation conditions and whether these effects are consistent with performance in real driving conditions. A double‐blind, placebo‐controlled, two successive two‐way crossover design was performed using cigarettes containing 20 mg of THC. Healthy occasional users of THC, aged 25–35 years, who had a consistent driving experience were included. The first two sessions were realized in simulation conditions, and the last two sessions were in real driving conditions. Driving performance was estimated through inappropriate line crossings (ILC) and the standard deviation of the vehicle's lateral position. Participants felt significantly drowsier and more tired after THC, whatever the driving condition. Driving stability was significantly impaired after THC, both in simulated and real driving conditions. We also found that ILC were significantly more numerous in driving simulation conditions, as compared to real driving. In conclusion, the driving simulator was proven to be more sensitive for demonstrating THC‐induced effects on driving performances. Driving simulation appears to be a good qualitative predictor of driving safety after drug intake.
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The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring “presence” to... more
The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring “presence” to use it as a measure for ecological validity in driving simulators. In this way, the purpose of this study is especially to investigate the relationship between subjective ratings of presence and physiological responses in virtual driving environments. Six driving scenarios were, thus, created, resulting from crossing two independent variables, i.e., the visual realism of the virtual environment (three virtual environments were created ranging from very realistic to not realistic) and the degree of visibility on the road for each virtual environment (two conditions were proposed : very good visibility and very bad visibility). Whatever the scenario, the driving task was always to follow a red car without losing sight of its location. To measure subjective presence, attention and emotional involvement, Presence, and Mood questionnaires were used. As measures of physiological response, heart rate and skin conductance level were acquired and more specifically the heart rate variability (HRV) was calculated from the acquired ECG data. Driving performance (standard deviations of speed and lateral position) was also analyzed. Fourteen participants (25.4±4.5 years of age) were placed in a fixed base driving simulator and performed consecutively the six driving scenarios in a different order. The results show correlations between Presence Questionnaire scores and both HRV parameters (time and frequency domains) and skin conductance level. In the study, HRV parameters and skin conductance level appeared to indicate the participant's degree of presence.
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Research Interests: Perception, Image Processing, Vision, Age, Alcohol, and 3 moreSteering, Accident Proneness, and Night
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The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children... more
The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children were previously reported to be posturally hyporeactive to visually perceived environmental motion in comparison with normal control children (Gepner et al., 1995), we sought to determine whether children with Asperger syndrome (AS) would share the same postural hyporeactivity to visual motion. Three autistic children with mild to severe motor impairments, three AS children with soft motor signs, and nine normal control children were tested for overall postural instability and postural reactivity to environmental motion. Results indicate, first, that overall postural instability is significantly reduced in autistic children compared with both AS and normal children. Second, although postural oscillations in the fore-aft axis become more attuned to the oscillation frequency of an immersive dynamic visual display as visual speed is increased, in both control and AS subjects, this is not the case in autistic children. Despite the small number of subjects tested in this study, our data confirm the existence of a visuopostural detuning in autistic children. Third, they argue for a correlation between visuopostural tuning and severity of motor signs in children with autistic spectrum disorders. Finally, they suggest a differentiation between children with autism and children with AS with regard to postural reactivity to fast visual motion. Neurophysiological implications of these results are discussed. In particular, a visuocerebellar pathway deficit hypothesis in autism is proposed.
Research Interests: Neurology, Education, Autism, Motion perception, Humans, and 15 moreChild, Depth Perception, Orientation, Female, Male, Optical Illusions, Oscillations, Posture, Asperger Syndrome, Postural Balance, Reference Values, Psychomotor Disorders, Autistic disorder, Child preschool, and Psychology and Cognitive Sciences
We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback,... more
We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback, VR feedback and VR feedback with the presence of a virtual coach, acting as a pacer. In VR feedback conditions, we observed a decreased level of perceived exertion and an increased level of enjoyment of physical activity, when compared to a regular exercise situation (no VR feedback). We also observed a shift in the subjects' attentional focus, from association (in the absence of VR feedback) to dissociation (in VR feedback conditions). Moreover, the presence of a virtual coach in the VR environment triggered a systematic regulation of the (virtual) displacement speed, whose relationship with perceived enjoyment and exertion require further work.
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Self-orientation perception relies on the integration of multiple sensory inputs which convey spatially-related visual and postural cues. In the present study, an experimental set-up was used to tilt the body and/or the visual scene to... more
Self-orientation perception relies on the integration of multiple sensory inputs which convey spatially-related visual and postural cues. In the present study, an experimental set-up was used to tilt the body and/or the visual scene to investigate how these postural and visual cues are integrated for self-tilt perception (the subjective sensation of being tilted). Participants were required to repeatedly rate a confidence level for self-tilt perception during slow (0.05°·s(-1)) body and/or visual scene pitch tilts up to 19° relative to vertical. Concurrently, subjects also had to perform arm reaching movements toward a body-fixed target at certain specific angles of tilt. While performance of a concurrent motor task did not influence the main perceptual task, self-tilt detection did vary according to the visuo-postural stimuli. Slow forward or backward tilts of the visual scene alone did not induce a marked sensation of self-tilt contrary to actual body tilt. However, combined body and visual scene tilt influenced self-tilt perception more strongly, although this effect was dependent on the direction of visual scene tilt: only a forward visual scene tilt combined with a forward body tilt facilitated self-tilt detection. In such a case, visual scene tilt did not seem to induce vection but rather may have produced a deviation of the perceived orientation of the longitudinal body axis in the forward direction, which may have lowered the self-tilt detection threshold during actual forward body tilt.
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The general aim of the present study was to investigate the effect of an interactive aerial view of the experienced environment during the encoding and retrieving of spatial information on the feeling of presence. Our findings showed that... more
The general aim of the present study was to investigate the effect of an interactive aerial view of the experienced environment during the encoding and retrieving of spatial information on the feeling of presence. Our findings showed that this real-time interactive aerial view (both small and large) during the encoding and retrieval of spatial information seems to led to a greater sense of presence. It is argued that the use of this aerial view, which provides a real-time allocentric viewpoint-dependent spatial representation, would ease the translation of a stored allocentric representation into an egocentric one, and this process, consequently, would help individuals to feel present in space.
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In order to avoid an impending collision while driving, the driver has to make a precise evaluation of the time available for taking an appropriate avoidance action (braking, swerving, etc.). This evaluation is made on the basis of visual... more
In order to avoid an impending collision while driving, the driver has to make a precise evaluation of the time available for taking an appropriate avoidance action (braking, swerving, etc.). This evaluation is made on the basis of visual information and involves the processing of local optical flow created by the presence of another vehicle. Previous studies suggest that this processing is also affected by the global optical flow due to the apparent motion of the surrounding surfaces, resulting from the driver’s self-motion. In another hand, the properties of the global optic flow are dependent on the visual characteristics of the environment and are used by the driver for controlling his/her trajectory and speed. In the present study, two experiments were conducted, trying to specify the respective role of global and local flow in two driving simulated tasks. Similar environments were manipulated and included road markings and uniform or textured road surfaces (with three densitie...
We previously showed that global optical flow due to the driver's self-motion could interfere with the analysis of another vehicle motion when arriving at an intersection. Such analysis is also dependent of optical local flows, such... more
We previously showed that global optical flow due to the driver's self-motion could interfere with the analysis of another vehicle motion when arriving at an intersection. Such analysis is also dependent of optical local flows, such as the visual trajectory of the other vehicle and/or relative visual motion between the other vehicle and visual cues included in the road environment (for example a road sign near the intersection). Here, we tested the role of road texture and of road environment in conditions of simulation. Several experimentations were carried out. In each of them, visual sequences were projected on a large tangent screen. The driver's displacement was rectilinear (70 km/h). Another vehicle was arriving perpendicularly to the intersection (at 10km/h). This vehicle could reach the intersection 1000 msec, 500 msec or 200 msec before or after the driver. The road texture and environment were manipulated (uniform road surface or textured road surface, présence or ...
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Much is known about how different spatial reference frames continually interact to support spatial navigation, but less explored is whether it is more crucial to process object-to-object information or egocentric heading information for... more
Much is known about how different spatial reference frames continually interact to support spatial navigation, but less explored is whether it is more crucial to process object-to-object information or egocentric heading information for effective orientation in a cluttered environment. To address this question, we evaluated the possible influence on spatial performance of an interactive aerial view of different scale (small vs. large) comprising an arrow indicating participants' egocentric heading. Results revealed that the presence of a small interactive aerial view including a visualized larger arrow facilitated the retrieval of stored spatial layout. These data are consistent with recent studies revealing the role of retrosplenial cortex in translating between different spatial reference frames, and may contribute to elucidate the continuous synchronization between the inter-object direction information in the environment with respect to egocentric current heading.
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In order to evaluate the role of edge lines in curve driving we examined steering behaviour in the face of unexpected gradual changes in road geometry. Experienced drivers (N=13) operating a fixed-base driving simulator steered a car... more
In order to evaluate the role of edge lines in curve driving we examined steering behaviour in the face of unexpected gradual changes in road geometry. Experienced drivers (N=13) operating a fixed-base driving simulator steered a car along a single-lane (3.80m or 7.60m wide) winding road. The experimental track consisted of eight 90° curves with radii of curvature varying between
Research Interests: Psychology and Steering
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Research Interests: Computer Graphics, Visualization, Computational Modeling, Information Visualization, Automata, and 11 moreCellular Automata, Boolean Algebra, Data Visualisation, Gpu programming, Real Time, Computer Graphic, Encoding, Emergent Behavior, Higher Dimensions, Multi Dimensional, and Multidimensional Systems
ABSTRACT The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring... more
ABSTRACT The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring "presence" to use it as a measure for ecological validity in driving simulators. The underlying assumption is that a person experiencing a strong sense of presence in the virtual environment will react in this environment as if it would be a real one. We propose to measure "presence" by measuring "attention" toward the driving task". Our objective is to demonstrate that the higher the subject's attention required by the primary driving task will be, the more the spatial presence will be felt. In the experiment we tried to vary "attention" by adding a dual task and by adding traffic and measure driving performance and subjective "presence" (MEC-SPQ; Measurement, Effects, Conditions-Spatial Presence Questionnaire). The main result is a lack of congruence between subjective and behavioral measures.
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ABSTRACT Modern training through virtual environments are widely used in transport in order to provide a high level of precision and more and more complex situations. These virtual environments provide training scenarii with automatic and... more
ABSTRACT Modern training through virtual environments are widely used in transport in order to provide a high level of precision and more and more complex situations. These virtual environments provide training scenarii with automatic and repetitive feedback to the trainees. Experienced learners receive too many aids and novice learners too few. In this research work, inspired by trial and error pedagogy, we have designed and evaluated a fluvial-navigation virtual training system which includes our GULLIVER module to determine the most appropriate level of feedback to display for learner guiding. GULLIVER is based on a decision-making module integrating uncertain data coming from observation of the learner by the system. An evidential network with conditional belief functions is used by the system for making decision. Several sensors and a predictive model are used to collect data in real time. Metaphors of visualization are displayed to the user in an immersive virtual reality platform as well as audio feedback. GULLIVER was evaluated on sixty novice participants. The experiment was based on a navigation case repetition. Two major results i) the learners get experience and error awareness from the virtual navigation with our system and ii) they show their capacity to navigate after the training, show the better performance of the GULLIVER system.
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We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback,... more
We herein report an experimental study examining the potential positive effects of Virtual Reality (VR) feedback during an indoor bicycling exercise. Using a regular bike coupled to a VR system, we compared conditions of no VR feedback, VR feedback and VR feedback with the presence of a virtual coach, acting as a pacer. In VR feedback conditions, we observed a decreased level of perceived exertion and an increased level of enjoyment of physical activity, when compared to a regular exercise situation (no VR feedback). We also observed a shift in the subjects' attentional focus, from association (in the absence of VR feedback) to dissociation (in VR feedback conditions). Moreover, the presence of a virtual coach in the VR environment triggered a systematic regulation of the (virtual) displacement speed, whose relationship with perceived enjoyment and exertion require further work.
Research Interests:
The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children... more
The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children were previously reported to be posturally hyporeactive to visually perceived environmental motion in comparison with normal control children (Gepner et al., 1995), we sought to determine whether children with Asperger syndrome (AS) would share the same postural hyporeactivity to visual motion. Three autistic children with mild to severe motor impairments, three AS children with soft motor signs, and nine normal control children were tested for overall postural instability and postural reactivity to environmental motion. Results indicate, first, that overall postural instability is significantly reduced in autistic children compared with both AS and normal children. Second, although postural oscillations in the fore-aft axis become more attuned to the...
Research Interests: Neurology, Education, Autism, Motion perception, Humans, and 15 moreChild, Depth Perception, Orientation, Female, Male, Optical Illusions, Oscillations, Posture, Asperger Syndrome, Postural Balance, Reference Values, Psychomotor Disorders, Autistic disorder, Child preschool, and Psychology and Cognitive Sciences
Visual motion perception plays a fundamental role in vehicle control. Recent studies have shown that the pattern of optical flow resulting from the observer's self-motion through a stable environment is used by the observer to... more
Visual motion perception plays a fundamental role in vehicle control. Recent studies have shown that the pattern of optical flow resulting from the observer's self-motion through a stable environment is used by the observer to accurately control his or her movements. However, little is known about the perception of another vehicle during self-motion--for instance, when a car driver approaches an intersection with traffic. In a series of experiments using visual simulations of car driving, we show that observers are able to detect the presence of a moving object during self-motion. However, the perception of the other car's trajectory appears to be strongly dependent on environmental factors, such as the presence of a road sign near the intersection or the shape of the road. These results suggest that local and global visual factors determine the perception of a car's trajectory during self-motion.
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A 37-year-old man experienced cortical blindness following a bilateral stroke in the territory of the posterior cerebral arteries. Four years later, the measurement of visual field defects (Goldmann perimeter) showed persistence of... more
A 37-year-old man experienced cortical blindness following a bilateral stroke in the territory of the posterior cerebral arteries. Four years later, the measurement of visual field defects (Goldmann perimeter) showed persistence of bilateral blindness with a 2-degree preservation of macular vision and a perifoveal sparing between 10 to 30 degrees of eccentricity in the left inferior quadrant. Despite this visual impairment, the subject was able to perform visually-guided locomotion. Moreover he consciously perceived visual motion in the blind parts of his visual field. CT and MRI showed a lesion involving most of the striated cortex. The visual cortex located in the internal occipito-parital regions was relatively spared. The contribution of this structure to extra-striated vision of motion is discussed.
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Self-orientation perception relies on the integration of multiple sensory inputs which convey spatially-related visual and postural cues. In the present study, an experimental set-up was used to tilt the body and/or the visual scene to... more
Self-orientation perception relies on the integration of multiple sensory inputs which convey spatially-related visual and postural cues. In the present study, an experimental set-up was used to tilt the body and/or the visual scene to investigate how these postural and visual cues are integrated for self-tilt perception (the subjective sensation of being tilted). Participants were required to repeatedly rate a confidence level for self-tilt perception during slow (0.05°·s(-1)) body and/or visual scene pitch tilts up to 19° relative to vertical. Concurrently, subjects also had to perform arm reaching movements toward a body-fixed target at certain specific angles of tilt. While performance of a concurrent motor task did not influence the main perceptual task, self-tilt detection did vary according to the visuo-postural stimuli. Slow forward or backward tilts of the visual scene alone did not induce a marked sensation of self-tilt contrary to actual body tilt. However, combined body and visual scene tilt influenced self-tilt perception more strongly, although this effect was dependent on the direction of visual scene tilt: only a forward visual scene tilt combined with a forward body tilt facilitated self-tilt detection. In such a case, visual scene tilt did not seem to induce vection but rather may have produced a deviation of the perceived orientation of the longitudinal body axis in the forward direction, which may have lowered the self-tilt detection threshold during actual forward body tilt.
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Interindividual differences influence the multisensory integration process involved in spatial perception. Here, we assessed the effect of visual field dependence on self-tilt detection relative to upright, as a function of static vs.... more
Interindividual differences influence the multisensory integration process involved in spatial perception. Here, we assessed the effect of visual field dependence on self-tilt detection relative to upright, as a function of static vs. slow changing visual or postural cues. To that aim, we manipulated slow rotations (i.e., 0.05° s(-1)) of the body and/or the visual scene in pitch. Participants had to indicate whether they felt being tilted forward at successive angles. Results show that thresholds for self-tilt detection substantially differed between visual field dependent/independent subjects, when only the visual scene was rotated. This difference was no longer present when the body was actually rotated, whatever the visual scene condition (i.e., absent, static or rotated relative to the observer). These results suggest that the cancellation of visual field dependence by dynamic postural cues may rely on a multisensory reweighting process, where slow changing vestibular/somatosensory inputs may prevail over visual inputs.
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ABSTRACT Virtual Reality prototyping can be used early in a design process, in order to question observers about the aesthetics of future vehicles, without the need for physical mock-ups. However, it is suspected that numerical display... more
ABSTRACT Virtual Reality prototyping can be used early in a design process, in order to question observers about the aesthetics of future vehicles, without the need for physical mock-ups. However, it is suspected that numerical display formats and solutions are not all equivalent, concerning the physical dimensions an observer is able to appreciate. This question is particularly acute, if one considers the transferability of conclusions reached using virtual prototyping to the real outcome of the design process.
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Robotics can provide technological solutions for improving the quality of life of disabled o r elderly people. The main objective of this project is to give these people some independence. The use of a mobile base mounted arm allows for... more
Robotics can provide technological solutions for improving the quality of life of disabled o r elderly people. The main objective of this project is to give these people some independence. The use of a mobile base mounted arm allows for the restoration of some of the manipulatory functions lost by the person. Due to the cost of t he final
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ABSTRACT We have designed and developed a virtual environment to train rugby ball passing skills. Seeking to validate the system's ability to correctly aid training, an initial experiment was performed to examine the effect of... more
ABSTRACT We have designed and developed a virtual environment to train rugby ball passing skills. Seeking to validate the system's ability to correctly aid training, an initial experiment was performed to examine the effect of stereoscopic technology and the physical screen's setup on the user's ability to perceive virtual distances correctly. Four participants with at least 10 years' experience of playing local-level rugby took part in the experiment to compare the combinations of different user positions compared to the physical screen, the use of stereoscopic presentation and the use of a floor screen to extend the field of view of the virtual scene. Conversely to what was expected, the participants did not respond well to perceived distance and these variables had little effect on the distance thrown.
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Previous research [e.g., Lobjois & Cavallo, 2007; 2009] has shown that seniors make many unsafe street-crossing decisions when vehicles approach at high speed, but miss many crossing opportunities when vehicle speed is low. It is... more
Previous research [e.g., Lobjois & Cavallo, 2007; 2009] has shown that seniors make many unsafe street-crossing decisions when vehicles approach at high speed, but miss many crossing opportunities when vehicle speed is low. It is generally assumed that elderly people have trouble in analyzing vehicle motion and thus mainly base their crossing decision on vehicle distance. The purpose of our
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The present study investigates the effect of three types of sensory feedback (visual, auditory and passive haptic) in a context of twohanded interaction with graphical menus in virtual environments. Subjects controlled the position and... more
The present study investigates the effect of three types of sensory feedback (visual, auditory and passive haptic) in a context of twohanded interaction with graphical menus in virtual environments. Subjects controlled the position and orientation of a graphical menu using their non-dominant hand and interacted with menu items using their dominant index fingertip. An ISO 9241-9-based multi-tapping task and a sliding task were respectively used to evaluate subjects’ performance in different feedback conditions. Adding passive haptic to visual feedback increased movement time and error rate, decreased throughput in the multi-tapping task, but outperformed visual only and visual-auditory feedback in the sliding task (in terms of movement time and number of times the contact between the finger and the pointer was lost). The results also showed that visual-auditory feedback, even if judged as useful by some subjects, decreased users' performance in the sliding task, as compared to visual-only feedback.
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The perceived direction of a grating moving behind an elongated aperture is biased towards the aperture's long axis. This “barber pole” illusion is a consequence of integrating one-dimensional (1D) or grating and two-dimensional (2D)... more
The perceived direction of a grating moving behind an elongated aperture is biased towards the aperture's long axis. This “barber pole” illusion is a consequence of integrating one-dimensional (1D) or grating and two-dimensional (2D) or terminator motion signals. In humans, we recorded the ocular following responses to this stimulus. Tracking was always initiated at ultra-short latencies (≈ 85 ms) in the direction of grating motion. With elongated apertures, a later component was initiated 15–20 ms later in the direction of the terminator motion signals along the aperture's long axis. Amplitude of the later component was dependent upon the aperture's aspect ratio. Mean tracking direction at the end of the trial (135–175 ms after stimulus onset) was between the directions of the vector sum computed by integrating either terminator motion signals only or both grating and terminator motion signals. Introducing an elongated mask at the center of the “barber pole” did not aff...
Research Interests: Visual perception, Nonlinear dynamics, Visual Neuroscience, Motion perception, Temporal dynamics, and 13 moreVisual Cortex, Humans, Reaction Time, Eye Movements, Time Factors, Eye Movement, Aperture Problem, Motion Integration, Psychomotor Performance, Neuropsychological Tests, photic stimulation, Psychology and Cognitive Sciences, and Medical and Health Sciences
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Research Interests: Motion perception, Linear models, Visual Cortex, Transparency, Vision, and 13 moreHumans, Cues, Motion processing, Visual System, Receptive Field, Spatial Scale, Primary visual cortex, Motion Segmentation, Area Mt, Stochastic Model, Retinal imaging, Psychology and Cognitive Sciences, and Medical and Health Sciences
Research Interests: Psychophysics, Perception, Eye tracking, Attention, Motion perception, and 15 moreOptical Flow, Humans, Depth Perception, Optic Flow, Reaction Time, Eye Movements, Optical Illusions, Adult, Eye Movement, Reflex, Motion Parallax, Binocular Disparity, Optokinetic Nystagmus, Psychology and Cognitive Sciences, and Medical and Health Sciences
We investigated the effects of stationary and moving textured backgrounds on ocular and manual pursuit of a discrete target that suddenly starts to move at constant speed (ramp motion). When a stationary textured background was... more
We investigated the effects of stationary and moving textured backgrounds on ocular and manual pursuit of a discrete target that suddenly starts to move at constant speed (ramp motion). When a stationary textured background was superimposed to the target displacement, the gain of the steady-state eye smooth pursuit velocity was significantly reduced, while the latency of pursuit initiation did not vary significantly, as compared to a dark background condition. The initial velocity of the eye smooth pursuit was also lowered. Both the initial acceleration and the steady-state manual tracking angular velocity were slightly, but not significantly, lowered when compared to a dark background condition. Detrimental effects of the stationary textured background were of comparable amplitude (approximately 10%) for ocular and manual pursuit. In a second condition, we compared ocular and manual pursuit when the textured background was either stationary or drifting. Initial and steady-state eye velocities increased when the textured background moved in the same direction as the target. Conversely, when the background moved in the opposite direction, both velocities were decreased. Eye displacement gain remained however close to unity due to an increase in the occurrence of catch-up corrective saccades. The effects of the moving backgrounds on the initial and steady-state forearm velocities were inverse to that reported for smooth pursuit eye movements. Neither manual nor ocular smooth pursuit latencies were affected.
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Research Interests: Motion perception, Space perception, Optical Flow, Vision, Humans, and 15 moreMovement, Optic Flow, Female, Gaze Direction, Male, Eye Movements, High Speed, Adult, Optokinetic Nystagmus, Virtual Simulation, Automobile driving, Psychomotor Performance, photic stimulation, Psychology and Cognitive Sciences, and Medical and Health Sciences
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The present study aimed at testing the general assumption that virtual reality can enhance the experience of exercising. More specifically, we tested the effects of sensory input (music and video feedback) during physical training on... more
The present study aimed at testing the general assumption that virtual reality can enhance the experience of exercising. More specifically, we tested the effects of sensory input (music and video feedback) during physical training on performance, enjoyment, and attentional focus by means of a computerized ergometer coupled with VR software. Twelve university students participated in the study. The experimental procedure consisted in a 2 × 3 × 4 mixed design, with two types of feedback (video feedback vs. video feedback and music), three course phases (e.g., flat, uphill, and downhill) and four sessions (task repetition). The virtual feedback was a video film of the course that participants had to complete. Video display speed was proportional to the participant's pedaling speed. Force feedback, applied to the real bicycle wheel, was proportional to the instantaneous course slope. The results showed a positive effect of task repetition on participants' performance only when v...
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We present the first assessment of motion vision in childhood autism. Postural reactivity to visually perceived motion was measured in five autistic children and 12 normal controls of the same chronological age. Anteroposterior as well as... more
We present the first assessment of motion vision in childhood autism. Postural reactivity to visually perceived motion was measured in five autistic children and 12 normal controls of the same chronological age. Anteroposterior as well as total body sway occurring on a force platform in response to movements in the visual environment were compared. Autistic children were posturally more unstable than normal children and quite insensitive to visually perceived environmental motion. Some implications of this impairment for sensorimotor and social communication development in infantile autism are discussed.
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We measured spatiotemporal contrast sensitivity and gait variables in a 60-year-old man who had spontaneous episodes of freezing gait without any sign of rigidity or tremor. One major factor triggering freezing was the characteristics of... more
We measured spatiotemporal contrast sensitivity and gait variables in a 60-year-old man who had spontaneous episodes of freezing gait without any sign of rigidity or tremor. One major factor triggering freezing was the characteristics of visual space, as freezing episodes occurred during spontaneous walking and passing through apertures and never during walking with eyes closed. Initiation and maintenance of locomotion were greatly facilitated when transverse stripes with optimal intervals were placed on the ground in front of the patient. On the other hand, contrast sensitivity to low-to-intermediate spatiotemporal frequencies was increased in this patient when compared with that of elderly controls. These data suggest that hypersensitivity to visual stimulation and to modifications of the visual environment, associated with abnormal ocular motor behavior, can be one factor leading to the freezing gait phenomenon, which could be called "hypersensitivity braking" and be considered as a sensorimotor disorder.
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We measured contrast sensitivity for static and laterally drifting vertical gratings in 12 young adults, 7 normal elderly adults, and 8 patients with Parkinson's disease (PD). We compared static and motion contrast sensitivity for... more
We measured contrast sensitivity for static and laterally drifting vertical gratings in 12 young adults, 7 normal elderly adults, and 8 patients with Parkinson's disease (PD). We compared static and motion contrast sensitivity for spatial frequencies of 0.25, 1, and 4 cycles per degree (cpd), and temporal frequencies of 1, 3, and 9 Hz. Results show that normal aging leads to a reduction of motion sensitivity for the spatial frequency of 0.25 cpd. Compared with elderly controls, PD patients do not present specific abnormalities in this domain. However, for spatial frequencies of 1 and 4 cpd and temporal frequencies of 1 and 3 Hz, motion sensitivity is worse than static sensitivity in PD patients and not in elderly controls. These findings suggest a specific deficit of motion perception in PD, and possible dopaminergic involvement in the control of visuospatial behavior.
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ABSTRACT Many studies have shown that during curve driving, the drivers have gaze fixation patterns in the vicinity of the tangent point (TP), this latter being the intersection between the inside edge of the road and its tangent passing... more
ABSTRACT Many studies have shown that during curve driving, the drivers have gaze fixation patterns in the vicinity of the tangent point (TP), this latter being the intersection between the inside edge of the road and its tangent passing through the driver position. The interest for the TP is mainly due to the fact that on one hand, its angular position is linked to the road curvature and therefore can be a control variable for the driver; and, on the other hand, it may correspond to a minimal speed in the optical flow. However, the TP is only motionless when the trajectory precisely follows the curve's geometry. In the present study, we measured gaze behavior during curve driving, with the general hypothesis that gaze cannot be stable when exposed to a global optical flow due to self-motion. We used a driving simulator coupled to a gaze recording system. Ten participants drove on a track composed of eight curves of various radii. Results show that gaze position is, as previously described, located near the TP. In addition, we observe the presence of a systematic optokinetic nystagmus (OKN) around the TP position. The OKN slow-phase direction does not match the foveal optic flow direction, while slow-phase speed is about half the local speed. When averaging the flow on larger areas, gaze and flow directions match better, and gaze and flow speeds are optimally matched for an optic flow integration over two degrees. We thus confirm that the TP is a privileged feature in the dynamic visual scene during curve driving. However, studying only gaze fixation is not fully relevant, because the TP is surrounded by optic flow, whose global characteristics induce retinal drifts and lead to OKN behavior. We consider that this must be taken into account for future models of vehicle control.
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A double-blind, placebo controlled, cross-over trial of sulfamethoxazole and trimethoprim was performed in a 62-year-old male patient who suffered from Machado-Joseph disease for 25 years. The patient, with cerebellar ataxia,... more
A double-blind, placebo controlled, cross-over trial of sulfamethoxazole and trimethoprim was performed in a 62-year-old male patient who suffered from Machado-Joseph disease for 25 years. The patient, with cerebellar ataxia, akinetic-rigid syndrome and motor weakness but without any pyramidal features, had been chair-bound for 3 years before the trial. Bactrim therapy markedly improved performance on a physical examination which tested standing and gait, as compared to placebo session. Walker-assisted gait was possible again. For the first time, evaluation of spatio-temporal contrast sensitivity was performed and also revealed an improvement after Bactrim therapy as compared to placebo. These results suggest that Bactrim may be effective in degenerative neurological diseases and that Bactrim may have an overall effect on neurotransmission rather than solely possessing antispastic properties.
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Observers viewed random-dot optical flow displays that simulated self-motion on a circular path and judged whether they would pass to the right or left of a target at 16 m. Two dots in two frames are theoretically sufficient to specify... more
Observers viewed random-dot optical flow displays that simulated self-motion on a circular path and judged whether they would pass to the right or left of a target at 16 m. Two dots in two frames are theoretically sufficient to specify circular heading if the orientation of the rotation axis is known. Heading accuracies were better than 1.5 degrees with a ground surface, wall surface, and 3D cloud of dots, and were constant over densities down to 2 dots, consistent with the theory. However, there was an inverse relation between the radius of the observer's path and constant heading error, such that at small radii observers reported heading 3 degrees to the outside of the actual path with the ground and to the inside with the wall and cloud. This may be an artifact of a small display screen.
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A large body of experimental evidence supports the hypothesis that dopamine is a functional neuromodulator at many levels of the visual system. Intrinsic dopaminergic neurons were characterized in most mammalian retina, including man.... more
A large body of experimental evidence supports the hypothesis that dopamine is a functional neuromodulator at many levels of the visual system. Intrinsic dopaminergic neurons were characterized in most mammalian retina, including man. These neurons give rise to a dendritic plexus covering the retina. Thus, dopamine seems to be involved in the organization of the ganglion cell and the bipolar cell receptive fields and modulates physiological activity of photoreceptors, both processes which underlie sensitivity and spatial selectivity of visual processing in the early stage of the visual system. Moreover, few data are now available concerning the functional significance of dopaminergic modulation of visual sensitivity in man. Parkinson's disease is a specific disorder of central dopaminergic systems. Abnormalities in the pattern-evoked potentials and electroretinogram have been found in parkinsonian patients. Contrast sensitivity, a useful tool for measuring visual spatio-temporal sensitivity in man, has also been shown to be modified due to this affection. Dynamic contrast sensitivity is primarily decreased in these patients, distinguishing them from the normal aging process. Because these modifications in shape of the contrast sensitivity function are reversed by L-Dopa, and that neuroleptic administration could reproduce them in schizophrenia patients, it was suggested that dopamine might tune the contrast sensitivity function in man. We have recently shown that subcutaneous apomorphine induces changes in contrast sensitivity in healthy volunteers, which preferentially affect motion sensitivity. These dopaminergic sensitive modifications in the shape of the contrast sensitivity function might reflect a change in the range of sensitivity of the visual system, both in dynamic and spatial properties. This could be explained by a modification in the spatial and dynamic properties of the ganglion cell responses in the retina. Moreover, we suggest both from our results and from the review of the literature that human psychophysical data confirm the hypothesis that dopamine may be involved in light retinal adaptation, as light-induced and dopamine-induced modifications in the shape in the contrast sensitivity function are quite similar.
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Research Interests: Mathematics, Motion perception, Postural Control, Space perception, Optical Flow, and 15 moreHumans, Cues, Orientation, Spatial Frequency, Oscillations, Posture, Spatial Orientation, Adult, Time Factors, Human Subjects, Visual Motion, Postural Stability, Postural Sway, Psychology and Cognitive Sciences, and Medical and Health Sciences
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Abstract: A fundamental aspect in driving is predicting critical events in the near future. A driver on a collision course, for example, has to accurately evaluate how close s/he is to the impending collision in order to brake or swerve... more
Abstract: A fundamental aspect in driving is predicting critical events in the near future. A driver on a collision course, for example, has to accurately evaluate how close s/he is to the impending collision in order to brake or swerve at the right time. In other words, s/he has to ...
Research Interests: Perception, Behavior, Forecasting, Forecast, TIME, and 8 moreBehaviour, Driver, COLLISION, Hazards, Time, Junction, Transport and Traffic, and Motor Skills
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Research Interests: Cognitive Science, Information Theory, Auditory Perception, Brain, Identification, and 15 moreHumans, Computer Simulation, Animals, Integration, Data Collection, Audio Visual, Bayesian Network, Biological cybernetics, Discrete random variable, Bayes Theorem, Graphical Model, Human Subjects, Causal Models, Decision Process, and Conditional Independence
In a placebo-controlled, double-blind study, we measured the effects of low dose lorazepam on attentional and motor factors involved in saccadic and smooth pursuit eye movements. We manipulated the temporal interval between the extinction... more
In a placebo-controlled, double-blind study, we measured the effects of low dose lorazepam on attentional and motor factors involved in saccadic and smooth pursuit eye movements. We manipulated the temporal interval between the extinction of the central fixation target and the appearance of a second eccentric target (gap/overlap step paradigm). The second target was either stationary (saccade trial) or moving in a direction opposite to the step (pursuit trial). Gap/overlap effects on the latency of saccadic and smooth pursuit eye movements were measured before and after oral intake of either lorazepam or placebo. Pharmacological effects on the dynamics and the accuracy of both types of eye movements were also investigated. In 14 healthy volunteers, we found that the temporal interval between fixation target offset and eccentric target onset modulates the latency of saccadic and smooth pursuit eye movements in a similar way. As compared to placebo, lorazepam significantly increased the latency of both types of eye movements, but did not modify the gap/overlap effect. Moreover, lorazepam significantly decreased the peak velocity of the first saccade towards the eccentric stationary target, as well as the gain of tracking towards the eccentric moving target. However, the overall accuracy of both behaviors was not significantly affected, indicating that systematic errors in foveating or tracking were detected and corrected by appropriate corrective or catch-up saccades, respectively. Results are discussed in terms of shared/different mechanisms for saccadic and pursuit systems in primates.
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While research indicates that benzodiazepine (BZD)-like drugs impair driving performance, it remains unclear (i) how far BZDs affect lane-keeping performance, compared with alcohol and (ii) to what extent this impact can realistically be... more
While research indicates that benzodiazepine (BZD)-like drugs impair driving performance, it remains unclear (i) how far BZDs affect lane-keeping performance, compared with alcohol and (ii) to what extent this impact can realistically be measured in a simulated environment. To clarify these issues, 16 healthy male drivers who had never previously taken BZDs underwent a randomized, crossover, double-blind, placebo-controlled driving paradigm (with the BZD lorazepam) in both real-world and simulated settings. Two lane-keeping variables, namely inappropriate line crossings (ILCs) and standard deviation of lateral position (SDLP), were recorded during the driving sessions. Analyses revealed that (i) a single lorazepam dose (2 mg given by mouth) caused higher SDLP increases than a blood alcohol concentration of above 0.05%, and that (ii) this BZD effect was amplified in the simulated driving setting, mainly for ILCs. As a consequence, we recommend that physicians be made more aware of BZD-related risks and that researchers make a clear distinction between the effects of BZD intake per se and the impact of simulated driving settings.
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We have previously shown that during self-motion in car driving situations, the perception of another car's trajectory relies both on global visual information such as the optical flow field, and on local visual information such... more
We have previously shown that during self-motion in car driving situations, the perception of another car's trajectory relies both on global visual information such as the optical flow field, and on local visual information such as the optical motion of the other car and the relative optical motion of the other car with respect to fixed elements in the environment. Here, we studied the environmental factors that contribute to perceptual judgements in relation to the observer's perceptual style (visual-field dependence vs. visual-field independence). In an experiment, observers were presented with visual scenes corresponding to the curvilinear self-motion of a driver approaching an intersection where another vehicle was arriving perpendicularly. The factors manipulated were the presence or absence of a spatial reference point (road sign near the intersection), environmental complexity ("road" or "spot" scenes), and the degree of field dependence/independence. Nine field-independent (FI) subjects and seven field-dependent (FD) subjects were asked to predict whether the other vehicle would reach the intersection before or after they would. Their responses were analyzed. Overall, subjects' judgements were more accurate with road environments and with a road sign, suggesting that the relative motion of the other vehicle with respect to fixed elements in the environment provides additional useful information. FI subjects were significantly more accurate than FD subjects, suggesting that the former are better at picking up relevant dynamic information in a complex environment.
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Patrick Pe´ ruch peruch@lnf.cnrs-mrs.fr Daniel Mestre Centre de Recherche en Neurosciences Cognitives CNRS, 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 ... Arthur, Hancock, & Chrysler, 1997; Foreman... more
Patrick Pe´ ruch peruch@lnf.cnrs-mrs.fr Daniel Mestre Centre de Recherche en Neurosciences Cognitives CNRS, 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 ... Arthur, Hancock, & Chrysler, 1997; Foreman & Wilson, 1996; Henry, 1992; Ruddle, Randall, Payne, & Jones ...
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When exposed to acoustic and visual stimuli, human observers may perceive them as originating either from a common or from distinct sources. Audiovisual perception includes both integration and segregation effects whose importance in the... more
When exposed to acoustic and visual stimuli, human observers may perceive them as originating either from a common or from distinct sources. Audiovisual perception includes both integration and segregation effects whose importance in the final percept depends on the stimuli spatio-temporal synchrony. This phenomenon has been studied through perception tasks, where a stimulus in one modality may be perturbed by another stimulus in the other modality [1, 2]. The authors have inferred some probabilistic relationships between the emitted and the reported stimulus location. We have performed a similar experiment to study and model these audiovisual integration and segregation phenomena. Subjects, seated in a dark room, were exposed to acoustic and visual stimuli presented either alone (unimodal case) or together (bimodal case). In the latter case, the stimuli co-occurred in time but not necessary in space. The subjects had to report the location of the visual or acoustic stimulus using a...
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In order to avoid an impending collision while driving, the driver has to make a precise evaluation of the time available for taking an appropriate avoidance action (braking, swerving, etc.). This evaluation is made on the basis of visual... more
In order to avoid an impending collision while driving, the driver has to make a precise evaluation of the time available for taking an appropriate avoidance action (braking, swerving, etc.). This evaluation is made on the basis of visual information and involves the processing of local optical flow created by the presence of another vehicle. Previous studies suggest that this processing is also affected by the global optical flow due to the apparent motion of the surrounding surfaces, resulting from the driver’s self-motion. In another hand, the properties of the global optic flow are dependent on the visual characteristics of the environment and are used by the driver for controlling his/her trajectory and speed. In the present study, two experiments were conducted, trying to specify the respective role of global and local flow in two driving simulated tasks. Similar environments were manipulated and included road markings and uniform or textured road surfaces (with three densitie...
We previously showed that global optical flow due to the driver's self-motion could interfere with the analysis of another vehicle motion when arriving at an intersection. Such analysis is also dependent of optical local flows, such... more
We previously showed that global optical flow due to the driver's self-motion could interfere with the analysis of another vehicle motion when arriving at an intersection. Such analysis is also dependent of optical local flows, such as the visual trajectory of the other vehicle and/or relative visual motion between the other vehicle and visual cues included in the road environment (for example a road sign near the intersection). Here, we tested the role of road texture and of road environment in conditions of simulation. Several experimentations were carried out. In each of them, visual sequences were projected on a large tangent screen. The driver's displacement was rectilinear (70 km/h). Another vehicle was arriving perpendicularly to the intersection (at 10km/h). This vehicle could reach the intersection 1000 msec, 500 msec or 200 msec before or after the driver. The road texture and environment were manipulated (uniform road surface or textured road surface, présence or ...
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Analyses of optic flow due to observer self-motion and analyses of the driver's gazing behavior during curve driving have suggested that the driver has a tendency to look at a location close to the tangent point on the inside edge of... more
Analyses of optic flow due to observer self-motion and analyses of the driver's gazing behavior during curve driving have suggested that the driver has a tendency to look at a location close to the tangent point on the inside edge of the road. Psychophysical experiments have further demonstrated that this visual strategy can be partly explained as an optimization of information pick-up. The main objective of the present study was to investigate, in an interactive simulation context, if this perceptual strategy might be used to define a visual aid for curve driving. In the framework of the French ARCOS project (Research action for secure driving; www.arcos2004.com), we used a mini-simulator developed by INRETS (MSIS-CIR group) in collaboration with FAROS company, with two main original characteristics: (1) during curve driving, the tangent point can be calculated and inserted in the visual scene in real-time and (2) a real-time eye- recording system (EYELINK, ® SMI) allows us to ...
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Much is known about how different spatial reference frames continually interact to support spatial navigation, but less explored is whether it is more crucial to process object-to-object information or egocentric heading information for... more
Much is known about how different spatial reference frames continually interact to support spatial navigation, but less explored is whether it is more crucial to process object-to-object information or egocentric heading information for effective orientation in a cluttered environment. To address this question, we evaluated the possible influence on spatial performance of an interactive aerial view of different scale (small vs. large) comprising an arrow indicating participants' egocentric heading. Results revealed that the presence of a small interactive aerial view including a visualized larger arrow facilitated the retrieval of stored spatial layout. These data are consistent with recent studies revealing the role of retrosplenial cortex in translating between different spatial reference frames, and may contribute to elucidate the continuous synchronization between the inter-object direction information in the environment with respect to egocentric current heading.
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ABSTRACT The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring... more
ABSTRACT The main contribution of this paper to the Cognitive Ergonomics field is to propose a new approach of the behavioral validity's assessment of driving simulators. In this paper, our ambition is to find a way of measuring "presence" to use it as a measure for ecological validity in driving simulators. The underlying assumption is that a person experiencing a strong sense of presence in the virtual environment will react in this environment as if it would be a real one. We propose to measure "presence" by measuring "attention" toward the driving task". Our objective is to demonstrate that the higher the subject's attention required by the primary driving task will be, the more the spatial presence will be felt. In the experiment we tried to vary "attention" by adding a dual task and by adding traffic and measure driving performance and subjective "presence" (MEC-SPQ; Measurement, Effects, Conditions-Spatial Presence Questionnaire). The main result is a lack of congruence between subjective and behavioral measures.
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The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children... more
The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children were previously reported to be posturally hyporeactive to visually perceived environmental motion in comparison with normal control children (Gepner et al., 1995), we sought to determine whether children with Asperger syndrome (AS) would share the same postural hyporeactivity to visual motion. Three autistic children with mild to severe motor impairments, three AS children with soft motor signs, and nine normal control children were tested for overall postural instability and postural reactivity to environmental motion. Results indicate, first, that overall postural instability is significantly reduced in autistic children compared with both AS and normal children. Second, although postural oscillations in the fore-aft axis become more attuned to the...
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Visual motion perception plays a fundamental role in vehicle control. Recent studies have shown that the pattern of optical flow resulting from the observer's self-motion through a stable environment is used by the observer to... more
Visual motion perception plays a fundamental role in vehicle control. Recent studies have shown that the pattern of optical flow resulting from the observer's self-motion through a stable environment is used by the observer to accurately control his or her movements. However, little is known about the perception of another vehicle during self-motion--for instance, when a car driver approaches an intersection with traffic. In a series of experiments using visual simulations of car driving, we show that observers are able to detect the presence of a moving object during self-motion. However, the perception of the other car's trajectory appears to be strongly dependent on environmental factors, such as the presence of a road sign near the intersection or the shape of the road. These results suggest that local and global visual factors determine the perception of a car's trajectory during self-motion.
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ABSTRACT Virtual Reality prototyping can be used early in a design process, in order to question observers about the aesthetics of future vehicles, without the need for physical mock-ups. However, it is suspected that numerical display... more
ABSTRACT Virtual Reality prototyping can be used early in a design process, in order to question observers about the aesthetics of future vehicles, without the need for physical mock-ups. However, it is suspected that numerical display formats and solutions are not all equivalent, concerning the physical dimensions an observer is able to appreciate. This question is particularly acute, if one considers the transferability of conclusions reached using virtual prototyping to the real outcome of the design process.
Robotics can provide technological solutions for improving the quality of life of disabled o r elderly people. The main objective of this project is to give these people some independence. The use of a mobile base mounted arm allows for... more
Robotics can provide technological solutions for improving the quality of life of disabled o r elderly people. The main objective of this project is to give these people some independence. The use of a mobile base mounted arm allows for the restoration of some of the manipulatory functions lost by the person. Due to the cost of t he final
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ABSTRACT We have designed and developed a virtual environment to train rugby ball passing skills. Seeking to validate the system's ability to correctly aid training, an initial experiment was performed to examine the effect of... more
ABSTRACT We have designed and developed a virtual environment to train rugby ball passing skills. Seeking to validate the system's ability to correctly aid training, an initial experiment was performed to examine the effect of stereoscopic technology and the physical screen's setup on the user's ability to perceive virtual distances correctly. Four participants with at least 10 years' experience of playing local-level rugby took part in the experiment to compare the combinations of different user positions compared to the physical screen, the use of stereoscopic presentation and the use of a floor screen to extend the field of view of the virtual scene. Conversely to what was expected, the participants did not respond well to perceived distance and these variables had little effect on the distance thrown.
The present study investigates the effect of three types of sensory feedback (visual, auditory and passive haptic) in a context of twohanded interaction with graphical menus in virtual environments. Subjects controlled the position and... more
The present study investigates the effect of three types of sensory feedback (visual, auditory and passive haptic) in a context of twohanded interaction with graphical menus in virtual environments. Subjects controlled the position and orientation of a graphical menu using their non-dominant hand and interacted with menu items using their dominant index fingertip. An ISO 9241-9-based multi-tapping task and a sliding task were respectively used to evaluate subjects’ performance in different feedback conditions. Adding passive haptic to visual feedback increased movement time and error rate, decreased throughput in the multi-tapping task, but outperformed visual only and visual-auditory feedback in the sliding task (in terms of movement time and number of times the contact between the finger and the pointer was lost). The results also showed that visual-auditory feedback, even if judged as useful by some subjects, decreased users' performance in the sliding task, as compared to visual-only feedback.
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ABSTRACT Many studies have shown that during curve driving, the drivers have gaze fixation patterns in the vicinity of the tangent point (TP), this latter being the intersection between the inside edge of the road and its tangent passing... more
ABSTRACT Many studies have shown that during curve driving, the drivers have gaze fixation patterns in the vicinity of the tangent point (TP), this latter being the intersection between the inside edge of the road and its tangent passing through the driver position. The interest for the TP is mainly due to the fact that on one hand, its angular position is linked to the road curvature and therefore can be a control variable for the driver; and, on the other hand, it may correspond to a minimal speed in the optical flow. However, the TP is only motionless when the trajectory precisely follows the curve's geometry. In the present study, we measured gaze behavior during curve driving, with the general hypothesis that gaze cannot be stable when exposed to a global optical flow due to self-motion. We used a driving simulator coupled to a gaze recording system. Ten participants drove on a track composed of eight curves of various radii. Results show that gaze position is, as previously described, located near the TP. In addition, we observe the presence of a systematic optokinetic nystagmus (OKN) around the TP position. The OKN slow-phase direction does not match the foveal optic flow direction, while slow-phase speed is about half the local speed. When averaging the flow on larger areas, gaze and flow directions match better, and gaze and flow speeds are optimally matched for an optic flow integration over two degrees. We thus confirm that the TP is a privileged feature in the dynamic visual scene during curve driving. However, studying only gaze fixation is not fully relevant, because the TP is surrounded by optic flow, whose global characteristics induce retinal drifts and lead to OKN behavior. We consider that this must be taken into account for future models of vehicle control.
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Research Interests: Motion perception, Space perception, Humans, Illusions, Female, and 3 moreMale, Young Adult, and Adult
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Research Interests: Cognitive Science, Information Theory, Auditory Perception, Visual perception, Brain, and 16 moreHumans, Computer Simulation, Animals, Data Collection, Audio Visual, Mutual Information, Probabilistic reasoning, Bayesian Network, Biological cybernetics, Bayes Theorem, Graphical Model, Human Subjects, Causal Models, Task Performance and Analysis, Decision Process, and Conditional Independence
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Patrick Pe´ ruch peruch@lnf.cnrs-mrs.fr Daniel Mestre Centre de Recherche en Neurosciences Cognitives CNRS, 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 ... Arthur, Hancock, & Chrysler, 1997; Foreman... more
Patrick Pe´ ruch peruch@lnf.cnrs-mrs.fr Daniel Mestre Centre de Recherche en Neurosciences Cognitives CNRS, 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 ... Arthur, Hancock, & Chrysler, 1997; Foreman & Wilson, 1996; Henry, 1992; Ruddle, Randall, Payne, & Jones ...
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The paper presents an initial framework for studying issues in the design and evaluation of Collaborative Virtual Environments based on immersive projection technology systems. The framework consists of a software platform, developed... more
The paper presents an initial framework for studying issues in the design and evaluation of Collaborative Virtual Environments
based on immersive projection technology systems. The
framework consists of a software platform, developed using
Virtools® software suite, which supports collaborative work
among collaborators in different immersive systems (CAVE®-
like environment, Workbench, etc.), and usability inspection of
each iteration of the platform. The objective of this setting for the framework was to gain insights on both technological aspects regarding the development of such a platform and human factors issues on collaborative work within Virtual Environments; and more importantly on the interrelation between technological and human factors aspects for building usable Collaborative Virtual Environments. A live demonstration of the platform connecting two CAVE®-like environments situated in geographically distant places was organized to collect feedback from participants. The demonstration provided the users with different interaction metaphors addressing the three main characteristics of collaborative work through Virtual Environments: awareness of others, context sharing, and negotiation and communication. Details about the platform, results of an informal observational study though the live demonstration and lessons learned from conducting such a framework are presented in the paper.
based on immersive projection technology systems. The
framework consists of a software platform, developed using
Virtools® software suite, which supports collaborative work
among collaborators in different immersive systems (CAVE®-
like environment, Workbench, etc.), and usability inspection of
each iteration of the platform. The objective of this setting for the framework was to gain insights on both technological aspects regarding the development of such a platform and human factors issues on collaborative work within Virtual Environments; and more importantly on the interrelation between technological and human factors aspects for building usable Collaborative Virtual Environments. A live demonstration of the platform connecting two CAVE®-like environments situated in geographically distant places was organized to collect feedback from participants. The demonstration provided the users with different interaction metaphors addressing the three main characteristics of collaborative work through Virtual Environments: awareness of others, context sharing, and negotiation and communication. Details about the platform, results of an informal observational study though the live demonstration and lessons learned from conducting such a framework are presented in the paper.
A particular affordance was used as a potential candidate for behavioral assessment of physical presence in virtual environments. The subjects’ task was to walk through a virtual aperture of variable widths. In the case of presence, the... more
A particular affordance was used as a potential candidate for behavioral assessment of physical presence in virtual environments. The subjects’ task was to walk through a virtual aperture of variable widths. In the case of presence, the subjects’ body orientation, while walking, was hypothesized to be adapted to the width of the aperture and to their own shoulder width. Results show that most subjects adapted their behavior to both their body architecture and the virtual width constraints. These subjects exhibited a behavioral transition from frontal walking to body rotation while walking through broad to narrow apertures. The same behavioral transition has already been documented in real environments (Warren and Whang in J Exp Psychol Human Percept Perform 13(3):371–383, 1987). This behavioral adjustment is thus assumed to be an objective indication of presence. Beyond these results, the present study suggests that every afforded action could be a potential tool for sensorimotor assessment of physical presence.
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We propose a graphics processor unit (GPU)-accelerated method for real-time computing and rendering cellular automata (CA) that is applied to hexagonal grids.Based on our previous work [9] –which introduced first and second dimensional... more
We propose a graphics processor unit (GPU)-accelerated method for real-time computing and rendering cellular automata (CA) that is applied to hexagonal grids.Based on our previous work [9] –which introduced first and second dimensional cases– this paper presents a model for hexagonal grid algorithms. Proposed method is novel and it encodes and transmits large CA key-codes to the graphics card and consequently, this technique allows to visualize the CA information flow in real-time to easily identify emerging behaviors even for large data sets. To show the efficiency of our model we first present a set of characteristic hexagonal behaviors, and then describe computational statistics for central processing unit (CPU) and GPU on a set of different hardware and operating system (OS) configurations. We show that our model is flexible and very efficient as it permits to compute CA close to a thousand times faster than classical CPU methods. Additionally, free access is provided to our downloadable software for hexagonal grid CA simulations.
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Research Interests: Computer Graphics, Visualization, Computational Modeling, Information Visualization, Automata, and 11 moreCellular Automata, Boolean Algebra, Data Visualisation, Gpu programming, Real Time, Computer Graphic, Encoding, Emergent Behavior, Higher Dimensions, Multi Dimensional, and Multidimensional Systems
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Previous research [e.g., Lobjois & Cavallo, 2007; 2009] has shown... more
Previous research [e.g., Lobjois & Cavallo, 2007; 2009] has shown that seniors make many unsafe street-crossing decisions when vehicles approach at high speed, but miss many crossing opportunities when vehicle speed is low. It is generally assumed that elderly people have trouble in analyzing vehicle motion and thus mainly base their crossing decision on vehicle distance. The purpose of our