The sense is so well adapted to its purpose that we normally assume that what we perceive are the actual objects (Calvert, 2000)
Eyes are the gateway through which electromagnetic radiation from our surroundings enters the visual system, exciting a flood of information from the distorted, two-dimensional image cast upon the sensitive cells of the retina. Most of vision takes place in the brain, and this begins in the retina, where the signals from neighboring receivers are compared and a coded message dispatched on the optic nerves to the occipital cortex, behind the ears, where the information is formatted and made available to the processing activities of the brain. The eye is essentially a motion detector, its original purpose when eyes began to evolve from light-sensitive pits in the pre-Cambrian (Calvert, 2000).
The act of seeing starts when visual stimuli pass sequentially through the eyes' optics, which are responsible for forming the retinal image; the photoreceptors, which sample and transduce the image into neural signals; and two to four retinal neurons, which transform and transmit those signals to the optic nerve and eventually to the central visual pathways. Considerable information is lost in these early stages of the process as evidenced by the close correspondence between the filtering properties of the optics and receptors, and some measures of visual sensitivity (Granrud, 1993)
Visual perception & Traffic accidents
On the roads of the USA 41,821 individuals were killed and 3.2 million injured during the year 2000. Given the high prevalence of automobile collisions, plenty of research has been conducted to understand the probable causes of such high rate of accidents. Such reports link errors in perception and decision-making as the premier probable cause of the majority of these accidents (Gray, 2004).
Sensing the movements of the world and the objects within it is the fundamental job for the visual system. Tasks such as driving a fast car down the freeway require a good sense of the movements of the driver and other objects on the road ahead (Snowden & Freeman, 2004). To sense such movements require what is known as "motion adaptation," which is a change in the motion-detecting cells in the brain that is produced by staring too long at moving objects (Gugliotta & Stein, 2001).
Research shows that motion adaptation, even though a very common situation, can put a driver at high risk for rear-end collisions. When a driver stares at an empty straight road for too long, it causes a change in his motion detecting brain-cells, leading to motion adaptation (Gugliotta & Stein, 2001). Keeping one's eyes on the highway ahead may actually present a danger because the brain plays tricks on drivers. These tricks of the brain mean that drivers on the open road often get too close to other cars before passing (Belchak, 2001).
Motion adaptation can have detrimental effects while the driver tries to overtake another vehicle, all the while focusing intently on the road ahead. Studies show that drivers started passing cars a fraction of a second later after driving five minutes on a straight empty highway than when they drove on a winding country road. This suggests that drivers over-estimate the time they need to pass safely whilst driving faster (Gugliotta & Stein, 2001).
Psychologists say that focusing in the road in front of the car for too long can be hazardous due to motion adaptat