A method of operating an electronic gaming machine includes displaying a moving object to a viewer on a display screen of the electronic gaming machine, detecting and tracking eye movement of the viewer in relation to the moving object over a predetermined time period, comparing the eye movement of the viewer in relation to the object over the predetermined time period to a displayed position of the object over the predetermined time period, and determining based on the comparison that the eye of the viewer in relation to the moving object is tracking the object. Related systems and devices are disclosed.