title: Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.
abstract: We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5-6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g), hypergravity (1.8 g), and normal gravity (1 g). Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.
authors.affiliation: Lyon Neuroscience Research Center, Bron, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.affiliation: Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Loureiro
authors.affiliation: International Space University, Strasbourg, France.
authors.forename: Duarte
authors.initials: D
authors.lastname: Sousa
authors.affiliation: European Space Research and Technology Center, European Space Agency, Noordwijk, The Netherlands.
authors.forename: Andre
authors.initials: A
authors.lastname: Zandvliet
mesh_terms: D000328:Adult; D004215:Distance Perception; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D008875:Middle Aged; D013026:Space Flight; D055815:Young Adult