Relationship between the head's and the body's center of gravity during normal standing.

An apparatus for the recording of head movements has been developed and a basic study was performed to determine the normal values of head movement and to estimate the significance of the head movement as a righting reflex. The locus traced by the head closely resembled that of the center of gravity, though shorter in overall length. The head also moves more slowly than the center of gravity. The phase delay of its movement was observed during standing with eyes closed. These results suggest that the head's movement is controlled by the body's center of gravity and that the latter moves in order to keep the head steady, maintaining the eyes in normal position.