Abnormal neck-righting response, which is said to be a physiological response when a child is placed flat on his or her back and the head is turned 90 degrees to the right or the left. With a normal neck-righting response, there follows a reflected torsion of the vertebral column in the same direction as the induced rotation of the neck. That is, the whole body follows the direction in which the head was turned. The response is present from birth to the age of five years. [from HPO]