Visuo-vestibular interaction in the reconstruction of travelled trajectories

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the others. Part of the illusionary reconstructed trajectories could be explained by assuming that subjects base their reconstruction on the ego-motion percept built during the stimulus' initial moments . In the current paper, we test this hypothesis using a novel paradigm: if the final reconstruction is governed by the initial percept, providing additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. The extra-retinal stimulus was tuned to supplement the information that was under-represented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used. Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement: perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but to a less veridical reconstruction in other conditions

Reconstructing passively travelled manoeuvres: Visuo-vestibular interactions.

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the other conditions. Part of the illusionary reconstructed trajectories could be explained if we assume that the subjects based their reconstruction on the ego-motion percept obtained during the stimulus' initial moments. In the current paper, we test this hypothesis using a novel paradigm. If indeed the final reconstruction is governed by the initial percept, then additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. We supplied extra-retinal stimuli tuned to supplement the information that was underrepresented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used. Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement; perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but it could also lead to less veridical reconstructions in other conditions

Visuo-vestibular interaction in the reconstruction of travelled trajectories

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the others. Part of the illusionary reconstructed trajectories could be explained by assuming that subjects base their reconstruction on the ego-motion percept built during the stimulus' initial moments . In the current paper, we test this hypothesis using a novel paradigm: if the final reconstruction is governed by the initial percept, providing additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. The extra-retinal stimulus was tuned to supplement the information that was under-represented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used. Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement: perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but to a less veridical reconstruction in other conditions

Integration of navigation and action selection functionalities in a computational model of cortico-basal ganglia-thalamo-cortical loops

This article describes a biomimetic control architecture affording an animat both action selection and navigation functionalities. It satisfies the survival constraint of an artificial metabolism and supports several complementary navigation strategies. It builds upon an action selection model based on the basal ganglia of the vertebrate brain, using two interconnected cortico-basal ganglia-thalamo-cortical loops: a ventral one concerned with appetitive actions and a dorsal one dedicated to consummatory actions. The performances of the resulting model are evaluated in simulation. The experiments assess the prolonged survival permitted by the use of high level navigation strategies and the complementarity of navigation strategies in dynamic environments. The correctness of the behavioral choices in situations of antagonistic or synergetic internal states are also tested. Finally, the modelling choices are discussed with regard to their biomimetic plausibility, while the experimental results are estimated in terms of animat adaptivity

Motor processes in mental rotation

Much indirect evidence supports the hypothesis that transformations of mental images are at least in part guided by motor processes, even in the case of images of abstract objects rather than of body parts. For example, rotation may be guided by processes that also prime one to see results of a specific motor action. We directly test the hypothesis by means of a dual-task paradigm in which subjects perform the Cooper-Shepard mental rotation task while executing an unseen motor rotation in a given direction and at a previously learned speed. Four results support the inference that mental rotation relies on motor processes. First, motor rotation that is compatible with mental rotation results in faster times and fewer errors in the imagery task than when the two rotations are incompatible. Second, the angle through which subjects rotate their mental images, and the angle through which they rotate a joystick handle are correlated, but only if the directions of the two rotations are compatible. Third, motor rotation modifies the classical inverted V-shaped mental rotation response time function, favoring the direction of the motor rotation; indeed, in some cases motor rotation even shifts the location of the minimum of this curve in the direction of the motor rotation. Fourth, the preceding effect is sensitive not only to the direction of the motor rotation, but also to the motor speed. A change in the speed of motor rotation can correspondingly slow down or speed up the mental rotation

How the Learning Path and the Very Structure of a Multifloored Environment Influence Human Spatial Memory

International audienceFew studies have explored how humans memorize landmarks in complex multifloored buildings. They have observed that participants memorize an environment either by floors or by vertical columns, influenced by the learning path. However, the influence of the building's actual structure is not yet known. In order to investigate this influence, we conducted an experiment using an object-in-place protocol in a cylindrical building to contrast with previous experiments which used rectilinear environments. Two groups of 15 participants were taken on a tour with a first person perspective through a virtual cylindrical three-floored building. They followed either a route discovering floors one at a time, or a route discovering columns (by simulated lifts across floors). They then underwent a series of trials, in which they viewed a camera movement reproducing either a segment of the learning path (familiar trials), or performing a shortcut relative to the learning trajectory (novel trials). We observed that regardless of the learning path, participants better memorized the building by floors, and only participants who had discovered the building by columns also memorized it by columns. This expands on previous results obtained in a rectilinear building, where the learning path favoured the memory of its horizontal and vertical layout. Taken together, these results suggest that both learning mode and an environment's structure influence the spatial memory of complex multifloored buildings

Driver trust and reliance on a navigation system: Effect of graphical display

International audienceThe present study investigates the influence of in-car navigation system graphic’s appearance on driver trust and reliance on the system. Two navigation systems were used: one with a realistic interface and one with a symbolic interface. During driving sessions on a simulator, the systems committed some guidance incoherencies regarding road signs present in the virtual environment. Subject’s trust and reliance on navigation systems were measured and compared between both systems. Result showed a higher level of trust for the realistic appearance system than for the symbolic one during the whole experiment. The presence of incoherencies decreased trust level for both systems but without any significant difference. No difference in system’s reliance was found but two groups of subjects were identified. One group is highly relying on both navigation systems’ indication when incoherence occurs whereas the other group was not. This study highlights the interaction of subjective items, as system graphical appearance, on user trust. Further experiments using a modified experimental setup may be needed to analyze precisely the influence on user relianceCette étude analyse l’influence de l’apparence graphique d’un système d’aide à la navigation sur le niveau de confiance et d’utilisation du système par le conducteur. Deux systèmes d’aide sont utilisés : un avec une interface graphique réaliste, et un avec une interface graphique simpliste. Durant des sessions de conduite réalisées sur simulateur, des incohérences dans le guidage du système vis-à-vis des panneaux présent dans l’environnement routier seront commises. Le niveau de confiance des sujets envers le système et son utilisation sont enregistrés et comparés entre les deux systèmes d’aide à la navigation. Les résultats montrent un niveau de confiance plus élevé tout au long de l’expérience pour le système avec une interface graphique réaliste. La présence d’incohérences de guidage engendre bien une diminution du niveau de confiance mais sans différence notable entre les deux systèmes. Aucune différence du niveau d’utilisation n’est enregistrée mais deux groupes de sujets sont identifiés. Un groupe de sujets se fie largement aux directions indiquées par les deux systèmes lors des incohérences, alors que l’autre groupe non. Cette étude souligne les interactions d’éléments subjectifs, comme l’apparence graphique d’un système, sur le niveau de confiance de l’utilisateur. Une autre phase expérimentale utilisant un protocole modifié serait nécessaire pour analyser en détail l’influence sur le niveau d’utilisation du système