Visual Scene Effects on the Somatogravic Illusion

The somatogravic illusion is a dangerous illusion that is believed to have caused a large number of mishaps in civilian and military aviation over the years. This illusion is usually experienced during forward acceleration, which creates a backward inertial force that combines with gravity to produce a resultant gravito inertial vector rotated backward from the pilot hence, the pilot perceives a pitching up of the aircraft. The false climb illusion demonstrates the limitations of the otolith organs in providing accurate information to the brain, when there is insufficient visual information to correct the misinformation hence, the objective of this research was to determine the relative importance of various visual scene cues in achieving visual dominance over nonvisual orientational inputs. The three orientational cues that were presented in both isolation and in various combinations were perspective splay, texture flow, and a horizon line. All of the visual scene cues were designed to depict level flight in the face of a pitch up somatogravic illusion SGI. It was hypothesized that some visual cues would be more effective than others in reducing the magnitude of the perceived somatogravic pitch up illusion when compared to the eyes closed SGI condition. No significant differences were observed between the perceived pitch during the eyes closed and any of the other visual conditions. The results suggest that the scenes may have been too basic, not bright enough, or not as realistic as a bright daytime scene.