Vision

Question 1

Theories of Color Vision

Answer 1

1. Trichromatic Theory (Young-Helmholtz): three types of colore receptors (cones) that each receptive to a different primary color (rbg), and all other colores are variations in the activity of these three receptors
2. Opponent-Process Theory (Hering): three types of bipolar cepectors (r-g, y-b,w-bk) some cells are excited by red and inhibited by green and so on. supported by negative afterimage, which involves seeing an image of an object in its complementary color after taken away.
   
   1. both theories used: trichromatic mechanism explain coding of color by the cones AND opponent-process is presumed to operate in the thalamus.

Question 2

Color Blindness

Answer 2

Color blindness/deficiency = result of genetic defect that affects on or more of the three types of cones OR disease or injury that affects the retina, optic nerve or other visual components.

1. Inherited form of color blindness: gene on the X chromosome, so males are more prone to color blindness. ** Females** would need to inherit the trait from both parents, but males vulnerable when his mother is either color blind or just a carrier of the trait.

Question 3

Depth Perception

Retinal Disparity

Answer 3

Depth Perception: depends on a combination of binocular and monocular cues.

1. Binocular cues: convergence and retinal (binocular) disparity and are responsible for depth perception of objects at relatively close distances.
2. Convergence: turning inward of the eys as an object gets closer and vice versa.
3. Retinal disparity: refers to the fact that our 2 eyes see objects in the world from 2 different views. Closer the object means the greater the disparity of the two images.
4. Monocular Cues: contribute to depth perception for objects at greater distances. Includes: relative size of objects, interposition overlap of objects, linear and atmospheric perspective and motion parallax (moon follows me).