Abstract
In order to study vestibular-visual interaction during active (voluntary) head movements, we devised a new test in which examinees turn their heads sinusoidally by 40° in time to a metronome. We set four different visual stimulus conditions as follows.
1. Mental arithmetic in the dark. 2. Continuous visual fixation on a lamp placed on the wall. 3. Continuous visual fixation on a lamp moving with the head. [2 and 3:a) in light b) in dark (imagine a lamp)] 4. Continuous visual pursuit of the lamp on the wall through a mirror installed diagonally in front of the eyes.
In a vestibular-visual coordinated situation (testing condition 2), all subjects could fix the eyes on the lamp on the wall whether it was switched on or off. However, as vestibular nystagmus becomes dominant in dyscoordinated conditions (vestibular-visual conflict, testing condition 3 and 4) even in light, especially during turns of high frequencies, visual fixation or pursuit is remarkably disturbed and inter-individual differences in these abilities become marked.
