title: Perceived radial translation during centrifugation.
abstract: BACKGROUND
  Linear acceleration generally gives rise to translation perception. Centripetal acceleration during centrifugation, however, has never been reported giving rise to a radial, inward translation perception.
  
  
  OBJECTIVE
  To study whether centrifugation can induce a radial translation perception in the absence of visual cues.
  
  
  METHODS
  To that end, we exposed 12 subjects to a centripetal acceleration with eyes closed. To avoid confounding with angular motion perception, subjects were fist rotated on-axis, and were shifted out fast and slow only after rotation sensation had vanished. They were asked for translation direction and velocity right after the shift-out, as well as after about 60 seconds of constant centrifugation.
  
  
  RESULTS
  Independent of fast or slow shift-out, the vast statistically significant majority of trials yielded an inward radial translation perception, which velocity was constant after 60 seconds of constant centrifugation.
  
  
  CONCLUSIONS
  We therefore conclude that during centrifugation, an inward radial translation perception does exist in humans, which perception reaches a constant, non-zero value during constant rotation, lasting for at least one minute. These results can be understood by high-pass filtering of otolith afferents to make a distinction between inertial and gravitational acceleration, followed by a mere integration over time to reach a constant velocity perception.
authors.affiliation: TNO Perceptual and Cognitive Systems, Soesterberg, The Netherlands.|Behavioural and Movement Sciences, VU University, Amsterdam, The Netherlands.
authors.forename: Jelte E
authors.initials: JE
authors.lastname: Bos
authors.affiliation: TNO Perceptual and Cognitive Systems, Soesterberg, The Netherlands.
authors.forename: Bruno J
authors.initials: BJ
authors.lastname: Correia Grácio
mesh_terms: D000054:Acceleration; D000328:Adult; D000465:Algorithms; D002498:Centrifugation; D003463:Cues; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D012399:Rotation; D012677:Sensation / Q000502:physiology*
keywords: Human centrifuge; centripetal acceleration; gravito-inertial resolution; path integration; self-motion perception; tilt-translation disambiguation