title: Spatial disorientation in gondola centrifuges predicted by the form of motion as a whole in 3-D.
abstract: BACKGROUND
  During a coordinated turn, subjects can misperceive tilts. Subjects accelerating in tilting-gondola centrifuges without external visual reference underestimate the roll angle, and underestimate more when backward-facing than when forward-facing. In addition, during centrifuge deceleration, the perception of pitch can include tumble while paradoxically maintaining a fixed perceived pitch angle. The goal of the present research was to test two competing hypotheses: 1) that components of motion are perceived relatively independently and then combined to form a three-dimensional (3-D) perception; and 2) that perception is governed by familiarity of motions as a whole in three dimensions, with components depending more strongly on the overall shape of the motion.
  
  
  METHODS
  Published experimental data from existing tilting-gondola centrifuge studies were used. The two hypotheses were implemented formally in computer models, and centrifuge acceleration and deceleration were simulated.
  
  
  RESULTS
  The second, whole-motion oriented hypothesis better predicted subjects' perceptions, including the forward-backward asymmetry and the paradoxical tumble upon deceleration. The predominant stimulus at the beginning of the motion and the familiarity of centripetal acceleration were important factors.
  
  
  CONCLUSIONS
  Three-dimensional perception is better predicted by taking into account familiarity with the form of 3-D motion.
authors.affiliation: Department of Mathematics, Colby College, 5845 Mayflower Hill, Waterville, ME 04901, USA. jeholly@colby.edu
authors.forename: Jan E
authors.initials: JE
authors.lastname: Holly
authors.forename: Katharine J
authors.initials: KJ
authors.lastname: Harmon
mesh_terms: D000054:Acceleration; D001359:Aviation; D002498:Centrifugation; D003198:Computer Simulation; D003221:Confusion / Q000503:physiopathology; D003654:Deceleration; D006801:Humans; D008962:Models, Theoretical; D009038:Motion; D013028:Space Perception / Q000502:physiology; D014722:Vestibule, Labyrinth / Q000503:physiopathology*