Abstract
International Standard ISO 2631 gives the reaction to horizontal vibration for the occupant of a building, a public transport system, the oscillations of the ocean and so on. These effects have not yet been evaluated by physiological methods as the criterion curves in the Standard are based on psychological evaluations of comfort and discomfort, rather than physiological investigations. Physiological and psychological effects of low frequency horizontal vibration on the whole-body were as follows: Changes in the autonomic nervous system were observed, in which the system tended to change from the state of predominance of the parasympathetic nervous system to that of the sympathetic nervous system, when the frequency exceeded the range 0.2 to 0.4Hz, typically around 0.3Hz.