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 was 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.
Collège de France/LPPA, 11, place Marcelin Berthelot, 75005 Paris, France. rene.bertin@college-de-france.fr
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D000054:Acceleration; D000328:Adult; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D007088:Illusions / Q000502:physiology; D008297:Male; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation; D004856:Postural Balance / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012399:Rotation; D013028:Space Perception / Q000502:physiology; D014722:Vestibule, Labyrinth / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*