title: Effects of background field-of-view and depth-plane on the oculogyral illusion.
abstract: This study examined the effects of background field-of-view and depth plane on the oculogyral illusion. Seven subjects viewed a stationary fixation stimulus during the postrotatory interval following a 45-sec constant-velocity chair rotation. The duration of the illusory movement of the fixation stimulus during the postrotatory interval was measured, along with the duration of the illusion of whole-body rotation (known as the somatogyral illusion) and the duration of the subject's slow-phase vestibular nystagmus. Subjects viewed the fixation stimulus by itself in a No-background condition or when surrounded by six background fields formed by the combination of two fields-of-view (35 degrees and 115 degrees) and three depth-planes (near, coplanar, and far). The different background fields inhibited the oculogyral illusion relative to the No-background condition but did not differ statistically from each other. The somatogyral durations better matched the oculogyral ones than did nystagmus decay, especially when a background field was present. These results suggest that the oculogyral illusion is more related to the experience of whole-body rotation than to oculomotor mechanisms and that the inhibitory effect of a background scene is only modestly affected by its field-of-view and depth plane.
authors.affiliation: Flight Motion Effects Branch, Biodynamics and Protection Division, Brooks Air Force Base, Texas, USA. fred.previc@brooks.af.mil
authors.forename: F H
authors.initials: FH
authors.lastname: Previc
authors.forename: N
authors.initials: N
authors.lastname: Ghani
authors.forename: K W
authors.initials: KW
authors.lastname: Stevens
authors.forename: D A
authors.initials: DA
authors.lastname: Ludwig
mesh_terms: D003867:Depth Perception / Q000502:physiology; D005364:Field Dependence-Independence; D006801:Humans; D007699:Kinesthesis / Q000502:physiology; D009039:Motion Perception; D009760:Nystagmus, Physiologic / Q000502:physiology; D009903:Optical Illusions / Q000502:physiology; D009949:Orientation / Q000502:physiology; D012399:Rotation; D012665:Semicircular Canals / Q000502:physiology; D014724:Vestibular Function Tests