Dr. Grandin emphasized that sheep, having a strong flocking instinct, are humanely handled by knowing how they move in the wild. They move as a flock in response to sudden threatening stimuli or cues from a leader. They move uphill more easily, and tend to move toward light. Their field of vision is wide because their eyes are widely-set in their head, but their depth perception is not acute unless their head is directed toward the ground. Heavily-wooled sheep may have limited vision because their facial wool limits their ability to see. Selection pressure in the flock breeding program should be directed so as to favor open-faced individuals, thus removing this trait from the flock. Sheep are easily distracted by movement, reflected light and novel higher-pitched sounds coming from the direction in which they are being moved. They will respond well if people and herder dogs work on the edge of the flight zone. Deep encroachment of the flight zone in an enclosed area may cause panic and pileups. Sheep should be moved at not more than a moderate to fast walk. They are not athletic animals, but they can be trailed successfully and humanely by keeping them moving steadily.