title: Rotation direction change hastens motion sickness onset in an optokinetic drum.
abstract: BACKGROUND
  Many stationary subjects who view the patterned interior of a rotating cylinder (optokinetic drum) experience motion sickness (MS) symptoms. An experiment was conducted to investigate the effects of rotation direction change on MS onset and severity. It was predicted that intermittently changing rotation direction would hasten MS onset due to an increased degree of visual/vestibular sensory conflict.
  
  
  METHODS
  There were 12 individuals who participated in the experiment (4 men, 8 women, mean age = 24.4 yr). Subjects viewed the interior of an optokinetic drum that rotated at 5 rpm (30 degrees x s(-1)). Drum rotation was either consistently in the same direction or rotation direction changed every 30 s. Eight MS symptoms were assessed at 2-min intervals using a subjective scale (0 = none, 1 = slight, 2 = moderate, 3 = severe).
  
  
  RESULTS
  Overall, MS onset was fastest when drum rotation direction changed. Specific MS symptoms significantly affected were dizziness, stomach awareness, and nausea.
  
  
  CONCLUSIONS
  These results suggest that a lack of correlation between the sensed and expected effects of motion alone can lead to MS. These results cannot be accounted for by a lack of correlation between sensed and expected gravitational vertical given that these were held constant across conditions.
authors.affiliation: Human Perception and Performance Laboratory, Department of Psychology, Saint Peter's College, Jersey City, NJ, USA. Fbonato@spc.edu
authors.forename: Frederick
authors.initials: F
authors.lastname: Bonato
authors.forename: Andrea
authors.initials: A
authors.lastname: Bubka
authors.forename: Meredith
authors.initials: M
authors.lastname: Story
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009041:Motion Sickness / Q000503:physiopathology*; D009068:Movement; D017120:Nystagmus, Optokinetic; D013997:Time Factors; D014796:Visual Perception