Lec 10 Color

Question 1

Coding at two levels

Answer 1

Ganglion cells- opponent colors

Cones- trichromacy

Question 2

Division of labor in vision

Answer 2

Color- color blindness
Contrast/brightness
Movement- motion blindness

Question 3

Types of color blindness

Answer 3

Lose r or g cones (1/20 males, 1/400 females)
Lose b cones (very rare)
Lose two cones (cone monochromat, rare)
Lose all cones (rod monochromat, rare, albinism)
Brain injury, cortical color blindness, very rare

Question 4

Cortical blindness

Answer 4

Damage to area V8
Lose subjective experience of color
World is like a black and white movie
Color lost but not shape or motion based on color

Question 5

Color vision across species

Answer 5

Humans: 3 cones
Some women: 4 cones (superwomen)
Bees: 3 cones (more UV, less red)
Birds: 4 cones (can see colors we can’t imagine) Some fish/turtles: 4 cones
Most mammals: 3 cones
Some butterflies: 5 cones

Question 6

Mantis shrimp

Answer 6

9+ cone dimensions!!!
IR--UV range 
Polarized light
UV alone supposedly as good as our color vision 
Trinocular vision
Detects transparent objects 
Fluoresces to attract mates

Question 7

Color component combinations in retina

Answer 7

R- G+ -> green yellow
R+ G- -> red
B+ Y- -> yellow

Question 8

Resolution limits for different senses

Answer 8

Position - vision best, audition & touch worse Where is it located? Lose vision, lose spatial resolution

Time - audition best, vision second, touch worst When did it happen?

Intensity - vision, audition, touch all relatively good How loud, bright, painful was it?
Braille is dots bc of resolution

Question 9

Cue integration

Answer 9

Brain weighs the more sensitive system and more reliable cues more heavily when interpreting scenes.
Vision is reliable for detecting positions. So visually perceived position of speaker captures sound.
Vision dominates.

Question 10

Why would the brain want vision to capture audio

Answer 10

Audio is processed faster
Chances that the two cues won’t be processed simultaneously. So the brain just selects one.

Audio trumps vision when faced with ambiguous information bc audio is more sensitive.

Question 11

Context guides perception

Answer 11

Comparison of sizes,
Motion of changing dots,
color
Is based on context

also in audio:
Interpreting sounds, speech, phrases (ie parsing words)

Visual context affects sound perception: Mcgurk, sometimes combined by object knowledge

Question 12

Vision loss- re

Answer 12

If sight is restored after age 15 and was lost before age 3, little is gained even after many years… Could be debilitating.

Suicide?
Mike’s sight- colors, outlines, but not illusory contours, no 3D cube, no depth from shading. Severe neural loss- slow recovery