You want the ball in the centre of your vision throughout the swing. If your head moves to the right, you might lose sight of the ball with your right eye. This drill helps you recognise if the ball is shifting from your central vision. Set up normally, close your left eye, and hit some balls (make sure you neck is down enough at address). Seeing the ball with only your right eye, you’ll quickly stop moving your head to the right or upward. This is a powerful drill, because losing sight of the ball is one of the most unsettling feelings a golfer can experience!