Psychophenomenon of paradoxical rotation provoked by acoustic and tactile stimuli

Two groups of healthy persons were examined during rotation at a constant speed. In the first group (10 subjects), a narrow band noise (500 Hz, 70 dB SPL) from a fixed loudspeaker was applied during the 120 degrees/s rotation. In the second group (20 subjects), a mild tactile stimulus was applied to the subject's head. All individuals from both groups were convinced that it was not the chair they were sitting in, but the sound source and the tactile stimuli which were rotating.