Damped pendular rotation was given with the initial maximum speed of 180°/s. The subject’s head was tilted forward at an angle of 30° from the upright position, or kept in the upright position, or tilted backward at 30° from the upright position. Electronystagmography was used to evaluate the maximal slow-phase eye velocity (mx SPEV) of the horizontal nystagmus. Differences existed in mx SPEVs of the horizontal nystagmus for the head-tilted positions at 30° forward or backward and that obtained in the upright position. The mx SPEV of the horizontal nystagmus in the upright position was higher than those acquired in the head-tilted posi