The up-down spatial reference has simplified tasks that are dependent upon spatial orientation throughout everyone’s life (Figure 7-01). When a space traveler enters weightlessness, this reference immediately disappears. Without this ever-present up-down perception vector, even conducting a visual search for an object within an orbiting spacecraft is quite difficult. As an astronaut floats about in weightlessness, her body orientation changes such that an object last seen above her head and to the right could soon after appear below her feet and to the left. The senses that usually maintain subconscious awareness of whole-body position relative to the immediate spatial environment no longer perform the task. The visual system is not capable of detecting the direction of gravity on Earth.
KeywordsHead Movement Spatial Orientation Mental Rotation Semicircular Canal Space Flight
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