1. An impaired subject detection system comprising: a camera for capturing images of an eye or eyes of a subject viewing a visual pattern; a visual pattern generation module for generating the visual pattern, wherein the visual pattern includes a scrolling window that reveals a message essentially one letter at a time, with other letters of the message obscured, the visual pattern being designed to cause a movement of an eye or eyes of the subject viewing the visual pattern via a display; an eye motion pattern computation module connected to the camera; and an assessment module connected to the eye motion pattern computation module.