They can be simple motor tics, such as blinking of the eyes or shrugging of the shoulders, or they can be complex motor
tics, resembling a purposeful movement.
Tics can also be vocal, such as grunting or verbalizing. Tics can occur in isolation or they may occur as part of Tourette's syndrome. In order for Tourette's to be diagnosed, there must be both motor and vocal tics that occur for over 1 year and start before the age of 18, and are not attributable to other causes.