On the Automatic Implementation of the Eye Involuntary Reflexes Measurements Involved in the Detection of Human Liveness and Impaired Faculties

To this day and in spite aggressive publicity campaigns, impaired driving due to the consumption of legal/illegal drugs such as alcohol and cannabis remains a major cause of road casualties. In order to detect such impairments, police officers first rely on an array of movement coordination tests (Standard Field Sobriety Tests: SFST) which are most of the time applied at road side. If enough suspicions are raised from the first phase of tests, a second set of more reliable tests are conducted at a police station. A driver would then be subjected to an assessment by a Drug Recognition Expert (DRE) in order to determine the type of intoxication (category of drugs) a driver is under as well as his capacity to operate any type of motor vehicle. In the present chapter as for the law enforcement community we define drugs as substance which, when taken into the human body, can impair the ability of a person to operate a vehicle safely. Drugs are mainly classified into seven categories, the Central Nervous System (CNS) depressants category includes some of the most abused drugs. Alcohol is considered the most familiar CNS depressants drug abused. The development of the Standardized Field Sobriety Tests (SFST), which was largely done through extensive research efforts performed at the Southern California Research Institute (SCRI) (Burns, 1995); (Burns & Gould, 1997) was a critical step toward the development of the DRE procedures (Page, 2000). The DRE testing process involves twelve distinct components in which the examination of the eyes and dark room examination are parts. The examination of the eyes allows the detection of certain drugs since these drugs can produce very easily observable effects on the eyes. One of the most noticeable of these effects is the horizontal gaze nystagmus. A person under the influence of certain drugs such as alcohol usually will exhibit Horizontal Gaze Nystagmus (HGN) which is an involuntary jerking of the eyes that occurs as the eyes turn toward the side while gazing at an object. The dark room examinations can also allow the detection of certain drugs since it affects how the pupils will appear and how they respond to light stimuli. Some drugs will cause the pupils to dilate and other to constrict. By systematically changing the amount of light entering a person’s eyes, one can also observe the pupil’s appearance and reaction.