Psychology - Structure of the Eye

Sensations can be defined as passive process of bringing information into the body and to the brain from the outside world. Perception can be defined as the active process of selecting, organizing, and interpreting the information brought to the brain by the senses. The visual system works on sensing and perceiving light waves. Light waves vary in their length and amplitude.

Structure of the Eye

Retina- inner membrane of the eye that receives information about light using rods and cone.

Lens- the transparent structure that focuses light into retina

Cornea- the round, transparent area that allows light into retina

4. Pupils- opening at the center of the iris which controls light entering eye

The eye is in many ways similar to a camera, but is much more complex. Light enters the pupil of the eye and is focused by the lens.

Perception

Perception is the interpretation of what is sensed

A very small portion of people do not see color at all, but view the world in shades of gray. Certain patterns confuse your eyes and brain, causing you to misjudge the size of a circle, or the length of a line. Color blindness is not a single problem but a variety of problems that affect color vision. Dark adaptation and the Purkinje Shift both

result from the shift from cone- to rod-vision. Color blindness affects mainly males, but it is a relatively slight vision problem compared to blindness. When we look at a object we are not only seeing that object but we see that background that it sits on. In vision, sensation occurs as rays of light are collected by the two eyes and focus on the retina. The stimulus for vision is light, which has three physical characteristics: wavelength, intensity, and pureness.

The receptor for vision is the eye, which contains rods for black-white vision and cones for color vision. Vision is poorest at the blind spot and best at the fovea. The psychological attributes are hue, brightness, and saturation. Complementary colors, as well as other colors, may be mixed in an additive or subtractive process. The differences between sensation and perception are more a matter of convenience than importance. Perception is composed of sensations to which the brain reacts in fact, some deny such distinctions can be made. . But there is no clean separation of sensations and perceptions.

In the eye there are cells which fire only if a stimulus is moving in a particular direction -- for instance, left to right. The same cell does not fire if an identical stimulus is moving right to left. In the very act of firing, this cell has already initiated the perception that the object is moving left to right.

In conclusion