Differentiation is the ability to move one body part without the unintentional movement of other parts. The ability to move one’s eyes independently from the head is required for reading text or facial expressions. Differentiation of fingers, one from another, is needed for fluid writing. Differentiation also allows us to mentally prioritize and focus on the task at hand.

Clues that may indicate a weakness in differentiation include:

• when concentrating, knocks things over at the table
• startle reactions
• unintentional body movement often interpreted by others as misbehaviours when standing in line, sitting at circle time, etc.
• unintentional movements of the head or jaw when the eyes are tracking
• unintentional movements of the opposite hand when one hand is engaged
• unintentional movement of the legs when one hand is engaged
• tics that involve more than just the eyes
• difficulty sorting out fingers for fine motor coordination
• movement of the tongue and/or mouth when concentrating on a task