Psych 5.3

depth perception

the ability to perceive the world in three dimensions

opponent-process theory

According to this theory, color is coded in opponent pairs: black-white, yellow-blue, and green-red. The basic idea is that some cells of the visual system are excited by one of the opponent colors and inhibited by the other.

lens

After passing through the pupil, light crosses the lens, a curved, transparent structure that serves to provide additional focus

optic nerve

Axons from the retinal ganglion cells converge and exit through the back of the eye to form it

iris

Colored part of the eye The pupil's size is controlled by muscles that are connected to the

color vision

Normal-sighted individuals have three different types of cones that mediate

visual info

Once inside the brain, visual information is sent via a number of structures to the occipital lobe at the back of the brain for processing. Visual information might be processed in parallel pathways which can generally be described as the "what pathway" and the "where/how" pathway.

pupil

When light levels are low, the pupil will become dilated, or expanded, to allow more light to enter the eye. When light levels are high, the pupil will constrict, or become smaller, to reduce the amount of light that enters the eye

trichromatic theory of color vision

all colors in the spectrum can be produced by combining red, green, and blue. The three types of cones are each receptive to one of the colors.

rods and cones

are connected (via several interneurons) to retinal ganglion cells

rods

are specialized photoreceptors that work well in low light conditions, and while they lack the spatial resolution and color function of the cones, they are involved in our vision in dimly lit environments as well as in our perception of movement on the periphery of our visual field

light waves

are transmitted across the cornea and enter the eye through the pupil

afterimage effect

describes the continuation of a visual sensation after removal of the stimulus. For example, when you stare briefly at the sun and then look away from it, you may still perceive a spot of light although the stimulus (the sun) has been removed. When color is involved in the stimulus, the color pairings identified in the opponent-process theory lead to a negative afterimage.

optic chiasm

is an X-shaped structure that sits just below the cerebral cortex at the front of the brain. At the point of the optic chiasm, information from the right visual field (which comes from both eyes) is sent to the left side of the brain, and information from the left visual field is sent to the right side of the brain.

pupil

is the small opening in the eye through which light passes, and the size of the pupil can change as a function of light levels as well as emotional arousal

cornea

is the transparent covering over the eye. It serves as a barrier between the inner eye and the outside world, and it is involved in focusing light waves that enter the eye.

Photoreceptors

known as cones, are light-detecting cells. The cones are specialized types of photoreceptors that work best in bright light conditions. Cones are very sensitive to acute detail and provide tremendous spatial resolution. They also are directly involved in our ability to perceive colo

retina

the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information

bioncular disparity

the slightly different view of the world that each of our eyes receives.

lens are also

ttached to muscles that can change its shape to aid in focusing light that is reflected from near or far objects.

fovea

which is part of the retina, the light-sensitive lining of the eye. The fovea contains densely packed specialized photoreceptor cells

binocular cues

which means that they rely on the use of both eyes.