Rolling-Over of the Body and the Righting Reflexes Acting on the Head

Their Development in Normal Infants

Abstract

The rolling-over movement of the body of an infant from the supine to abdominal position in infants involves a number of righting reflexes, especially those of the head. Therefore, the development of the righting reflexes acting on the head was studied in relation with that of rolling-over of the body in 33 normal infants.The infants were seen once every month from 1 month through 12 months of age, the developmental history including that of rolling-over was taken, and the righting reflexes acting on the head were examined. The infant to be examined was held at bilateral axillae with the hands of the examiner while either 1) at the vertically suspended position or 2) at the sitting position. The body of the infant was inclined 30° to either side.
The righting reflex acting on the head was judged positive when the head was brought to the upright position while the body was inclined. The righting reflex acting on the head on suspension became positive at 3 to 8 months of age, coinciding with rolling-over of the body. The righting reflex acting on the head at the sitting position became positive a few months earlier.
Five infants who developed one-sided righting reflex acting on the head on suspension rolled over to the opposite side. When they acquired righting reflex acting on the head on both sides a few months later, they also could roll over on both sides.
These findings indicate that rolling-over of the body is closely related to the righting reflex acting on the head on suspension, and that one-sided rolling-over results from asymmetrical development of the labyrinthine or optical righting reflex.