title: Color vision with rapid-onset acceleration.
abstract: BACKGROUND
  Only sporadic information exists concerning perceived color shifts at increased G-loads. The purpose of this study was to investigate whether or not color vision is affected by rapid onset high G7-loads up to +9 Gz, and specifically whether perception of hue changes.
  
  
  METHODS
  There were 10 male subjects, 9 with normal color vision and 1 with red-green protanomaly, all accustomed to Gz-loads in a human centrifuge. Each subject was tested on a total of 60 Gz-exposures with 10 s periods at +3, +5, +7, and +9 Gz in the centrifuge on three different days. G-onset rate was 6 G x s(-1). The subjects wore an anti-G suit and performed straining maneuvers if necessary to maintain vision. Five square color stimuli of medium saturation (yellow, red, blue, green, and gray) were projected one at a time on a screen in front of the subject, who gave his hue response orally.
  
  
  RESULTS
  In 96.6% of exposures to various Gz-loads, the subjects responded by correctly naming colors. (The statistical analyses of the results were done for the subjects with normal color vision, with the protanomalous subject excluded.) Hue shifts occurred at the higher +Gz-levels, including 7.7% of the +9 Gz exposures. Yellow was the hue most frequently perceived as changed. Hue shifts were reported for yellow in 11% and 16% of the +7 and +9 Gz exposures, respectively. Hue shifts at +9 Gz occurred as frequently as blackout and G-LOC together. However, statistical analyses showed no significant effects for +Gz-load.
  
  
  CONCLUSIONS
  Absolute identification of the color stimuli of medium saturation was stable and was not significantly affected by the rapid onset +Gz-loads up to and including +9 Gz.
authors.affiliation: FOI, Swedish Defence Research Agency, formerly National Defence Research Establishment, FOA, Sweden. ulf.balldin@brooks.af.mil
authors.forename: U I
authors.initials: UI
authors.lastname: Balldin
authors.forename: G
authors.initials: G
authors.lastname: Derefeldt
authors.forename: L
authors.initials: L
authors.lastname: Eriksson
authors.forename: P M
authors.initials: PM
authors.lastname: Werchan
authors.forename: P
authors.initials: P
authors.lastname: Andersson
authors.forename: J T
authors.initials: JT
authors.lastname: Yates
mesh_terms: D000054:Acceleration; D000337:Aerospace Medicine / Q000379:methods; D002498:Centrifugation; D003118:Color Perception / Q000502:physiology*; D003627:Data Interpretation, Statistical; D006801:Humans; D018471:Hypergravity; D008297:Male