Fig. 1.
The Visual and Vestibular Investigation System (VVIS) chair. During off-axis centrifugation, the net linear acceleration stimulating the otoliths is the vector sum of the centripetal force (Ac) and gravity (Ag), i.e., the GIA. The vector sum is shown. The gravity vector is pictured pointing upward (as a balancing force) to visualize the tilt illusion sensed during centrifugation. When the GIA is interpreted as the spatial vertical, the subject experiences a sensation of tilt. In this case, the constant force of gravity together with centripetal force, each of them 1 g, gives a perceived tilt of 45°. Reprinted from Hallgren et al. (2015) with permission of Macmillan Publishers Ltd, copyright 2015.