Abstract
We examined the separate and combined effects of scene rotation and body rotation on the ability of subjects to set a visual rod to horizontal. Subjects sat in a cockpit in a sphere, 2.6 m in diameter, lined with dots. They set a rod to horizontal before, during, and after roll motion of the sphere, the self, or both scene and self. Subjects fell into three groups. Those in one group, whom we call “visual subjects”, experienced full self rotation (vection) when sitting upright in the rotating sphere. However, these subjects set the test-rod to horizontal with reasonable accuracy when they themselves were rotated in the stationary sphere. They therefore used both visual and non-visual inputs. Those in the second group, whom we call “non-visual, disoriented subjects”, maintained the test-rod reasonably horizontal when stationary in the rotating sphere but became severely disoriented when they were rotated in the stationary sphere. They therefore did not use either visual or non-visual inputs effectively. Those in the third group, whom we call “non-visual, oriented” subjects, were non-visual because we they did not experience full vection when sitting in the rotating sphere but they did not become disoriented when rotated in the stationary sphere. Thus, they did not rely heavily on vision but had reliable inputs from the non-visual sense organs. The tests we have developed could be used to probe the extent to which people use visual and non-visual information for orientation during roll.
Supported by DRDC Toronto Contract W7711-017739/A