Space Illusions In weightlessness, down" cues from the inner ear otolith organs are absent. Astronauts are thought to rely more heavily on vision Many astronauts perceive a" subjective vertical. When it changes direction it can cause disorientation and motion sickness Inversion illusions Visual reorientation EVA acrophobia -sudden fear Common immediately illusions(VRIs)-surface of falling towards the Earth after reaching orbit below feet seems like floor 16. 423 SBE(Neurovestibular Countermeasures)16.423 SBE (Neurovestibular Countermeasures) Space Illusions • In weightlessness, “down” cues from the inner ear otolith organs are absent. Astronauts are thought to rely more heavily on vision. • Many astronauts perceive a “subjective vertical”. When it changes direction, it can cause disorientation and motion sickness. Inversion Illusions - Common immediately after reaching orbit Visual Reorientation Illusions (VRIs) - surface below feet seems like floor EVA acrophobia - sudden fear of falling towards the Earth