Visual Perception - Eye Habits (1982)

as we drive along a typical highway at 40 to 50 miles an hour more information floods in on us in a few minutes than is put into a computer for the launching of a space vehicle [Music] the faster we go the more information we must see identify and interpret and the more decisions we must make on what we see or think we see [Music] in big city driving we may face 200 traffic events and have to make at least 20 decisions per mile an inexperienced driver will make at least one error every two miles most of our driving information is collected by our eyes about ninety percent of our impressions of the driving scene are visual the eye is something like a camera which takes snapshots transmitting separate images to the brain in rapid succession but the eye is also different from the camera because it collects information in two special ways our central or foveal vision is a narrow three degree cone in the central part of our site central vision is important in how we learn to estimate distance and how we read details in the traffic scene the experienced driver focuses his attention down the road along his line of central vision where objects appear almost stationary establishing an intended path of travel the good drivers attention is focused on the selection of details in the traffic scene and on the distance between his car and objects ahead in addition to our central vision we also experience peripheral or side vision side vision is not as sharp as central vision but it is more sensitive to light and movement it helps us detect important information coming into the traffic scene even though we are not looking directly at such objects however the useful effect of our side vision decreases as the speed of our vehicle increases the eye is the main source of driver information and driver errors are often the result of poor eye habits oh ralph you missed the turn oh i know i know the driver we just saw became confused because he was unable to process the information he needed in time to execute a safe maneuver we know that for the most part driving is a task of information processing a driver receives information from several senses of these senses vision accounts for more than 90 percent of the information input in order for us to learn what visual cues are used in driving we must be able to describe the driver's visual search process how visual information is gathered by the eye in driving has been studied by means of an eye movement recording system developed at the driving performance laboratory at the ohio state university as this driver scans the traffic scene a spot of light reflected from her eye is superimposed over a recorded image of the driving situation this spot shows us where the driver is looking or fixating research confirms the fact that our eyes move in a series of rapid jerky movements between each movement the eye pauses for a fraction of a second and then darts to another part of the scene these pauses are known as fixations it is during these brief periods of fixation that the eye gathers visual information eye fixations are very rapid lasting only about one tenth to three tenths of a second in heavy traffic a driver can afford to spend less than a second total time in viewing traffic signs and signals high accident rates are common on curves the eye habits of the experienced driver begin to operate several seconds before the curve is reached this driver is selecting the important clues the curvature of the road the condition of the berm or shoulder and other traffic he uses the lane lines in close to his car to maintain proper lane position and he looks ahead as far as possible to maintain his intended path of travel [Music] in a merging situation experienced drivers maintain lane position by glancing to the right side of the road always coming back to the intended path of travel good drivers start sampling the mainstream 10 seconds before reaching the merging point with experience some driving tasks do not require that every fixation be directed only to essential traffic information this driver for example selects a visual target but is still able to maintain control of his vehicle with very brief glances at his intended path of travel proving the importance of side vision in driving this driver was told to fixate on the car to his right while maintaining proper distance behind the car directly ahead as the i-spot movement shows this experienced driver is able to follow the car in front without looking directly at it tired or fatigued drivers tend to fixate lower and to the right often looking directly at the road surface eye movements also show the effect of alcohol on driving this sober driver fixes his attention on the car at the left a driver under the influence of alcohol fixate straight ahead without noticing anything to the sides of his intended path of travel he has developed a fixed stare how do new drivers learn to search student drivers at the ohio state university show different search patterns than those of experienced drivers they go through a three-stage development in the first stage beginning drivers show an active search pattern with many fixations often on unimportant clues in the second stage new drivers show an in out pattern sharing their fixations for near lane position with glances ahead in the third stage we find the normal pattern of experienced drivers who fixate far ahead using their side vision for lateral position information how can we reach this third stage how can we improve our visual habits in driving first concentrate on your intended path of travel the skillful driver moves in the traffic stream with a space margin in front behind and to each side of his car he uses his central vision to get details of the scene and to estimate distances second look well ahead aim high in steering give yourself a visual lead time of at least 12 seconds to the vehicle ahead of you that's about one city block at about 30 miles an hour two city blocks if you're doing 55. third keep your eyes moving constantly scanning helps you gather more information and prevent you from developing a fixed stare or the blank stare that comes from thinking about things which take your attention away from the driving scene scanning also means checking your rear vision and side vision mirrors in quick glances once every block at least or every five seconds in heavy traffic because of the blind spots to your rear and to your right head checks are an important part of the scanning process always turn your head in the direction or lane you plan to move into whenever you change your intended path of travel never rely on the rear vision mirrors alone and always return your central vision to your intended path of travel use your side vision for information along the edges of the traffic scene remember concentrate on your intended path of travel look well ahead and keep your eyes moving constantly scanning the traffic scene getting the big picture in an increasingly complex traffic scene your life and the lives of others depends upon improving your eye habits in driving [Music] you