1. The Structure of the Visual System

2. Cornea The clear, curved bulge on the front of the eyeball
Protects the eye

3. Iris Ring of muscle tissue that forms the colored portion of the eye;
Regulates the size of the pupil by changing its size--allowing more or less light to enter the eye

4. Pupil Controls the amount of light entering the eye
In bright conditions the iris expands, making the pupil smaller
In dark conditions the iris contracts, making the pupil larger

5. Lens
A transparent structure behind the pupil in the eye that changes shape to focus images on the retina

6. The Lens Nearsightedness Aka Myopia
Nearby objects are seen more clearly than distant objects (eye is elongated)
Farsightedness
Aka Hyperopia
Can see things far away but not close up (eye is shortened)

7. Parts of the Eye - Retina

8. Retina Light-sensitive surface at the back of the eyeball
Contains cells that convert light energy to nerve impulses
Made up of three layers of cells
Receptor cells
Bipolar cells
Ganglion cells

9. Fovea The central focal point of the retina
The spot where vision is best (most detailed)
(FOCUS)

10. Optic Nerve
The nerve that carries visual information from the eye to the occipital lobes of the brain

11. Blind Spot
The point at which the optic nerve travels through the retina to exit the eye
There are no rods and cones at this point, so there is a small blind spot in vision

13. The Eye

14. Visual Processing in the Retina

15. Receptor Cells Rods Cones Respond to less light than do cones
Night vision
Can detect sharp details and color
Need more light than the rods

16. Bipolar Cells
Gather information from the rods and cones and pass it on to the ganglion cells
Cells that form the middle layer in the retina
Cones each have their own; multiple rods share one

17. Ganglion Cells
Pass the information from the bipolar cells through their axons
Together these cells form the optic nerve.
The top layer of the cells in the retina

19. The Nature of Light

20. Hue
The color of light as determined by the wavelength of the light energy
Includes: red, orange, yellow, green, blue, indigo and violet (ROY G BIV)

21. Wavelength

22. Amplitude The brightness of light as determined by height of the wave
The taller the wave, the brighter the color

23. Color Vision

24. Trichromatic Theory Aka Young-Helmholtz
Theory of color vision that says cones are sensitive to red, green and blue light
All the colors we see are a combination of these three colors

25. Color Deficient Vision
People who lack one of the three types of cones
Usually the red or green receptors are missing
Usually referred to as color blindness
Is inherited and found more in males

27. Ishihara Color Test

30. Nike’s Color Rush Uniforms Bills v. Jets

32. The Problem: Trichromatic Theory leaves some parts of the color vision mystery unsolved

33. Opponent-Process Theory
Proposed by Ewald Hering
We process 4 primary colors combined in pairs
Demonstrated by afterimages