Visual Perception: Eye Anatomy, Color Theory, and Processing

Wavelength

The distance from the peak of one light

wave to the peak of the next.

• Electromagnetic wavelengths vary from

the short gamma rays to the long pulses of radio transmission

Intensity

The amount of energy in a light or sound wave,

which influences what we perceive as

brightness or loudness.

Determined by the wave's amplitude (height) higher wave length more intense the light is

Cornea

the eye's clear, protective outer layer,Covering the pupil and Iris

Pupil

the adjustable opening in the center of the eye through which light enters

Iris

a ring of muscle tissue that forms the colored portion

of the eye around the pupil and controls the size of the pupil opening

Lens

the transparent structure behind the pupil that

changes shape to help focus images on the retina

Retina

the light-sensitive back inner surface of the eye,

containing the receptor rods and cones plus layers of

neurons that begin the processing of visual information

Accommodation

The process by which

the eye's lens changes

shape to focus images

of near or far objects on the retina

Cones

Retinal receptor cells

that are concentrated

near the center of the

retina and that

function in daylight or

in well-lit conditions.

The cones detect fine

detail and give rise to

color sensation.

Rods

Retinal receptors

that detect black,

white, and gray and

are sensitive to

movement.

Necessary for

peripheral and

twilight vision,

when cones don't

respond.

Fovea

the central focal point in the retina, around which

the eye's cones cluster

optic nerve

the nerve that carries neural impulses from

the eye to the brain

Blind spot

the point at which the optic nerve leaves the

eye, creating a "blind" spot because no receptor cells are Located there

Young-Helmholtz trichromatic theory(color)

The theory that the retina contains 3 different types of color

receptors -- one most sensitive to red, one to green, and one

to blue -- which, when stimulated in combination, can

produce the perception of any color

opponent-process theory

The theory that opposing retinal

processes (red-green, yellow-blue,White-black) enable color vision

feature detectors

Nerve cells in the visual cortex that respond to specific

features of the stimulus, such as edges, angles, or movement

Parallel processing

Processing multiple aspects of a stimulus or problem

simultaneously.

The brain's natural mode of information processing for many functions,

including vision.

Contrasts with the step-by-step (serial) processing of most computers

and conscious problem solving