The DidRen Laser test was used to standardize the visually elicited rotational motion of the participant’s head-neck complex. A description of the system is summarized in the figure below. It is composed of three photosensitive sensors including photocells, a fine laser beam, and a computer equipped with a customized software that calculates the time between two consecutive “hits” of the sensors and that allows to display the results. A chair without armrests was placed at 90 cm from a vertical panel equipped with the 3 sensors arranged horizontally and located 52 cm apart. The distance between the participant and the wall was chosen so that the participant performed a 30° rotation both to the left and right sides of the bodyline. ![. (a). DidRen Laser installation device including the 3 photosensitive sensors and the placement of markers on the head (Head= H, Left Head= L.H, Right Head=R.H) and the shoulders (Left Acromion= L.A, Right Acromion=R.A, 7th Cervical vertebrae=C7). (b) Head rotation is executed around a vertical axis (X) in a horizontal plane (Y-Z). ][1] . (a). DidRen Laser installation device including the 3 photosensitive sensors and the placement of markers on the head (Head= H, Left Head= L.H, Right Head=R.H) and the shoulders (Left Acromion= L.A, Right Acromion=R.A, 7th Cervical vertebrae=C7). (b) Head rotation is executed around a vertical axis (X) in a horizontal plane (Y-Z). [1]: https://files.osf.io/v1/resources/rsuh2/providers/osfstorage/5cdeb1f023fec4001ae01970?mode=render