vision chapter 3-2

How does the eye transform particles of light energy into colorful sights that the mind registers into vision?

Conversion of one form of energy into another.

Sensory transduction: the process by which our sensory systems encode stimulus energy as neural messages.

Transduce (transform) light energy into neural messages that the brain then processes into what you consciously see.

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 inner surface of the eye, contain the receptor rods and cones plus layers of neurons that begin the processing visual information.

Cones: retinal receptor cells that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Detect fine detail and color.

Scientists still debate exactly how we see color!

Cones will be sensitive to one of three colors: red, green or blue.

Rods are responsible for vision at low light levels. They do not mediate color vision.

Retinal receptors that detect black, white, and gray; necessary for peripheral and twilight vision, when cones don’t respond.

Fovea: The ventral 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 nerves leaves the eye, creating a “blind” spot because no receptor ells are located there.

Dark Adaptation: The recovery of the eye’s sensitivity to visual stimuli in darkness after exposure to bright lights. (example: night blindness)

Light Adaptation: The recovery of the eye’s sensitivity to visual stimuli in light after exposure to darkness.

http://www.tangle.com/view_video.php?viewkey=09652b3ef45514be1e9a&sp=1

“The Miracle of Eyesight”

The sharpness of vision, which can be affected by small distortions in the eye’s shape.

Nearsightedness: nearby objects are seen more clearly.

Farsightedness: faraway objects are seen more clearly than near objects.

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

The processing of several aspects of a 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 of conscious problem solving.

Requires about 30 percent of the cerebral cortex.

Brain takes in visual content through the eyes back to the visual cortex and adjacent areas.

Compares it to stored memories. Connects what is seen with memory,

enabling recognition!