空間識と身体の平衡

起立時の高さと身体の動揺に関する検討

抄録

Spatial orientation is influenced by many factors such as vision, hearing, vestibular input, and so on. However, the details of when and which factor exert influence on this process remain mostly unknown. We investigated the influence of height on spatial orientation under various conditions.
Body movement was recorded by stabilometry for 30 seconds under each of three visual conditions (eyes open without gaze fixation, eyes closed, and eyes open with gaze fixation) at 0 m, 1 m, 2 m, and 10 m22 cm high in 30 normal volunteers (14 males and 16 females) who had no history of vertigo or dizziness. Eight of subjects claimed to be acrophobic.
The total length of the gravity center movements reflected the body sway best. The sway was minimal with eyes open and gaze fixated, and maximal with eyes closed. The sway increased at 10 m22 cm high, but was almost the same at 1 m and 2 m high. The acrophobic group was clearly worse than the non-acrophobic group at 10 m22 cm high. Their total shifting length increased because they became tense and shivered fractionally.
Visual information which served as the base was useful for spatial orientation, and the mental factor of fear caused tension and the sway increased especially in the acrophobic group at 10 m22 cm high.