In a car factory, there are 25 workers on the assembly line. The person at the end of the line signals when the parking lot is full of cars to the front of the line, and production stops. The front of the line then signals when production should begin again. Therefore, the front of the line is the ultimate controller of output. The controller has the ability to respond in two ways. In positive feedback, the front could continue to make cars until all the parts are gone. In negative feedback, production would stop until the lot was empty again. What is the role of the person at the front of the line in controlling the production output?