The Eye Flashcards
What does JND stand for?
Just Noticeable Difference
What is the JND for weight?
2%
What is the physical stimulus for vision?
Light
How much of light is visible?
Only a small part
What is Light Amplitude?
Distance from top to bottom of wave length
What does Light Amplitude tell us?
How much energy the light contains and determines brightness.
What is wave length?
Distance between peaks in wave length.
what does wave length tell us?
Different lengths give us different colors.
What is the Cornea?
Transparent protective covering that bends the light wave (where contacts sit)
What is the Aqueous Humor?
A watery substance in the back of Cornea. Nourishes the eye, keeps it glassy and rounded.
What is the Pupil?
Adjustable opening in the center of Iris that constricts and dilates.
What is the Iris?
Translucent donut shaped muscle that controls the size of the pupil.
What is the Lens (lenses)?
Focuses the visual image on the retina.
One is concave and one is convex.
What is are Ciliary Muscles?
Changes the shape of the lens to bend light rays.
Occular Accommodation
Changes in the lens as an object gets closer/ further from you.
What is Myopia?
Nearsightedness
What is Hyperopia?
Farsightedness
What is the Vitreous Humor?
A jelly like substance that makes up most of the eye that gives shape.
What is the Retina?
A multilayered light sensitive tissue. Where transduction occurs.
What are the Photoreceptors, where are they located?
Located in the Retina, Preforms transduction.
What are the Bipolar Nuerons, where are they located?
Located in the Retina, Pass signals from photoreceptor cells to Ganglion cells.
What are the Ganglion Cells, where are they located?
Located in the surface of the Retina, Makes up the optic nerve (creates action potential)
What are Rods, where are they, and main characteristics?
Type of photoreceptor. The periphery of the eye. Highly sensitive t o light, works best in low light. Primarily black and white, not sensitive to color.
What are Cones, and main characteristics?
Type of photoreceptor. The center (fovea) of the eye. Not sensitive to light, works better in bright light. Good at distinguishing color.
What is the Fovea?
A small area in the center of the retina that is densely packed with cones only.
What is the Blindspot?
The point at which the optic nerve exists the eye (No receptor cells, you cannot see there).
What is the Optic Nerve?
Takes messages to the brain.
What is light adaptation?
Increasing ability to see in the light as time in the light increases (leaving a movie theatre).
What is Dark Adaptation?
Increasing ability to see in the dark as time in the dark increases (turning off the downstairs lights at night).
Trichromatic Theory
Cones are most sensitive to wavelengths corresponding to blue, green, and red
What is the limitation to the Trichromatic Theory?
It cannot explain the afterimage (turn of the lights and see an American flag).
What color are short wavelength cones sensitive to?
Blue.
What color are medium wavelength cones sensitive to?
Green.
What color are long wavelength cones sensitive to?
Reddish Yellow.
Opponent-Process Theory
Color-sensitive visual elements are grouped into pairs, pair members oppose each other (opposites).
Red/Green, Blue/Yellow, Black/White.
Dual-Process Theory
Combines the Trichromatic and Opponent-Process theories.
What does the Dual-Process Theory change about the Opponent-Process Theory?
It begins in the Ganglion cells, and not the cones.
Colorblindness
Inability to sense certain colors.
Trichromats
people with normal color vision.
Dichromat
people who are color-blind in one of the three systems.
Monochromat
people who are completely color-blind.
