Effects of a visual frame and of low radial accelerations on the visually perceived eye level.
The purpose of this study was to determine how the combined effects of a reference frame and of very low gravito-inertial forces produced by centrifugation affect the visually perceived eye level (VPEL). Twenty subjects were instructed to set a luminous target to the VPEL under various experimental conditions involving two main factors: (1) visual context (frameless, frame centered, frame moved down 50 mm, and frame moved up 50 mm) and (2) gravito-inertial context (motionless, Gi1 = 9.81001 m/sec2 and Gi2 = 9.95 m/sec2). The visual context significantly reduced the lowering of VPEL in darkness as caused by radial acceleration; this confirms the prevailing role of vision versus propriosomesthesis. However, under condition Gi2, there was a significant effect on the VPEL in spite of the presence of the luminous frame; this demonstrates that VPEL processing involves both visual and propriosomesthesic information. Furthermore, the VPEL varied linearly with the vertical shift of the luminous frame for any of the gravito-inertial conditions used in this study, but, under condition Gi2, the VPEL was shifted downward.
Raphel
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Centre de Recherches du Service de Santé des Armées, La Tronche, France.
Barraud
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PA
Koessler
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Cian
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C
D000054:Acceleration; D000328:Adult; D001288:Attention; D003623:Dark Adaptation; D005260:Female; D005364:Field Dependence-Independence; D006112:Gravitation; D006801:Humans; D007699:Kinesthesis; D008297:Male; D008875:Middle Aged; D009949:Orientation; D011434:Proprioception; D011601:Psychophysics; D012399:Rotation; D014796:Visual Perception