Sight – perhaps the most miraculous of the senses, which we sadly tend to take for granted -is a process which 7 – of light entering the eye is controlled by the pupil, which P( <&., *’‘‘-mi has the ability to dilate and contract. The cornea and lens, the shape of which is adjusted by the culinary body, focus ‘ ~ the light on to the retina, where receptors convert it into eye, therefore, is to translate the electromagnetic vibrations of light into packets of nerve impulses which are transmitted to the brain for interpretation.
The retina consists of approx.- mutely 130 million light-sensitive cells, which are either cone shaped or rod shaped. The cone-shaped cells respond to color, and it is believed that the cones are distributed evenly to react to one of the red, green, or blue light primaries. As a sensation experienced by humans and some animals, perception of the color of the light wavelengths so received is a complex neurophysiological process.
Among mammals, only humans, primates, and a few other species can recognize colors. Perceptual psychologists believe that, once the nerve impulses have been received and an object has been perceived as an identifiable entity, it tends to be seen as a stable object having permanent characteristics, despite variations in its illumination, the position from which it is viewed, or the distance at which it appears.
Thus, an individual viewing a new scene interprets it by synthesizing past experience with sensory cues present in the new scene – using depth cues such as linear perspective, partial concealment of a far object by a near one or the presence of aerial perspective ’haze’. Fortunately for the graphic designer, however, the brain can be deceived! Indeed, this deception is the very basis of much graphic design.
For example, it is because the brain is conditioned to associate the converging lines and shaded faces of a building with its three-dimensional depth, that, by drawing the building using converging lines and shaded surfaces on a two-dimensional surface, we trick the brain into seeing the drawing as having three dimensions.