All tasks done by individuals on a Scrum Team must be chosen voluntarily. If one Team Member, in any way, tells another Team Member what task to work on, this breaks the principle of self-organization that is essential to creating a high-performance Scrum team. Team leads, project managers, functional managers and other people in roles of authority to assign tasks must give up that authority completely when it comes to the people on a Scrum team. This self-organizing behavior allows individual team members to consider their own talents, capacity, interest, motivation etc., when choosing a task. All of those inner conditions are not as well known by other people and so assigning tasks tends to be sub-optimal. When a Team Member considers those inner conditions about him or her self, and also takes into consideration the needs of the team, an optimal task choice can be made. If someone in a position of authority does assign tasks, it creates a habit of deferring to authority which quickly destroys any possibility of a high-performance team developing.