1. Sensation and Perception--VISION
The Biological Basis of Behavior: Unit III

2. 4.2 Vision (How does the eye enable vision?)
Light
The eye
Color vision
Color blindness

3. Light Light is electromagnetic energy.
Not all light is visible to humans.
We only see a small spectrum of waves.
Wavelengths vary from fractions of an inch to miles. (Distance between 2 wave crests.)
ROY G BIV

5. The Eye Similar to a camera with film. Outer clear membrane-Cornea
Amount of light that enters the eye is determined by the size of the opening in the colored muscular tissue (Iris).
Pupil-the opening of the eye.
Adjusts automatically
Sensitive to emotions

6. The Eye (contd.)
Lens-the transparent structure of the eye that focuses light on the retina.
Adjusts to the distance of objects by changing its thickness.
Squinting

7. The Eye (contd.) Retina Photoreceptors
the light-sensitive inner surface of the eye that contains the rods, cones, and neurons that process visual stimuli.
Photoreceptors
the neurons that are sensitive to light (rods & cones).

9. The Eye (contd.) The Blind Spot Rods and Cones
Where the optic nerve exits the eye.
Lacks photoreceptors
Rods and Cones
Rods-sensitive to brightness (b&w) million
Cones-sensitive to color. 7 million

10. The Eye (contd.) Dark and Light Adaptation
Your adaptation to see in low light continues to improve for up to 45 minutes.
Adaptation to bright light happens much more quickly. Why?

12. The Eye (contd.) Visual Acuity The sharpness of vision
Eye exams
Snellen Chart
Near sighted
Far sighted
Your lens harden during middle age.

14. LASIK eye surgery
(2:35)

16. The Eye (contd.) Color vision Wavelength of light determines the color
People with normal color vision see any color in the spectrum of visible light.
Dogs and cats see fewer colors
Insects, birds, fish, and reptiles experience a wide variety of colors

21. The Eye (contd.) The Color Circle
Colors of the spectrum bent into a wheel
Opposite colors are complimentary

22. The Eye (contd.) Cones and Color Vision
Trichromatic Theory-cones are sensitive to either blue, green, or red.
Images you see on TV consist of thousands of small pixels.
Various combinations create the spectrum

24. The Eye (contd.) Afterimages
The afterimage of a color is its complimentary color.
You perceive an afterimage when you have viewed a color for a while and then the color is removed. (Rod/Cone fatigue)
Opponent Process Theory
Red vs Green
Blue vs Yellow

27. The Eye (contd.) Color Blindness
People without normal vision are said to be “color blind.”
Absence or malfunction of the cones
Particularly common is red-green color blindness

30. http://news. nationalgeographic

31. Color Constancy