1. An attention detection system for determining whether a computer application should execute an action, comprising: an image captured by a camera that contains the user's head and face; a display device for providing visual information to the user; a yaw center line defined as a line in an x-z yaw plane that bisects the user's head into two approximately equal parts; and a facial pose estimation system that processes the image and uses the yaw center line to determine whether a user is gazing at the display device and instructs the computer application whether to execute an action based on the determination.