Week 4

Question 1

Trichromatic Theory of color vision

Answer 1

Suggested that three different receptor mechanisms are responsible for color vision

Question 2

metamers

Answer 2

two different stimuli that give observer the same experience of color

Question 3

Experiemnt suggesting observer needs 3 wavelengths of light to match the color

Answer 3

Color-matching exp by Maxwell

Question 4

Observer with color deficiencies need how many?

Answer 4

2

Question 5

Problem with Trich Theory

Answer 5

Blindness occurs in pairs of green/red and blue/yellow.
Individuals then have trouble visualizing combos of red/green or blue/yellow.
Color afterimages show exhaustion of one color (green) produces another color (red)

Question 6

Opponent-process theory

Answer 6

(Ewald Herring)
Suggests three mechanisms process colors in pairs r/g b/y and black/white.
They respond opposing fashion: + to red and - to green.
(lose one, lose color vision for both colors)

Question 7

Single-cell recordings

Answer 7

In 1950s found opponent cells which are located in the retina, LGN (parvocellular and koniocellular layers), and in the cortex.

Question 8

Opponent cells

Answer 8

Responded in an excitatory manner to one
range of wavelength and inhibitory to another.

This supported opponent-process theory except the black-off white-on was not apparent in color vision.

Question 9

Recall selective adaptation where neurons selective for specific stimuli get fatigued when exposed for a long time. For opponent cells, if we are exposed to blue for a long time then blue-on and yellow-off will be fatigued. If we were then shown a white screen we should get a release from inhibition (where the cell inhibited starts to fire more), what color should we see?
a. Red
b. Yellow
c. Blue
d. Green
e. Rainbow 🌈🦄

Answer 9

bruh they didn’t give the answer but yellow?

Question 10

How are he physiological mechanisms underlying the trichromatic and opponent process theories of color are compatible?

Answer 10

• Trichromatic theory explains the responses of the cones in the retina.
• Opponent-process theory explains neural response for cells with those cones in their receptive fields. These signals affect activity in retina, LGN and cortex.

Question 11

There is __ single module for color perception

Answer 11

no

Question 12

Inferior temporal lobe

Answer 12

involved with object recognition (patients with visual agnosia)

Question 13

Parietal lobe

Answer 13

involved with spatial relationships (difficulty with remembering landmark)

Question 14

Dorsal pathway

Answer 14

Where/How

Question 15

Ventral pathway

Answer 15

What

Question 16

Dorsal and ventral pathway

Answer 16

• Originated in retina and continue through ganglion cells in the LGN
• Have some interconnections
• Receive feedback from higher brain areas

Question 17

Short wavelengths

Answer 17

419-nm, S-cone

Question 18

Medium wavelengths

Answer 18

531-nm, M-cone

Question 19

Long wavelengths

Answer 19

558-nm, L cone

Question 20

Ablation studies

Answer 20

what areas of the brain are associated with specific behaviors:
- First, an animal was trained on perceptual capacities and then measure their behavior.
- Second, a specific part of the brain was removed or destroyed (ablated).
- Finally, test the animal again to see if their behavioral results change.

Question 21

Object discrimination problem

Answer 21

• Removal of inferior temporal lobe tissue, resulted in problems with the object
  discrimination task
• “What pathway” in brain because it is critical for target identification

Question 22

Landmark discrimination problem

Answer 22

• Removal of parietal lobe tissue, resulted in problems with the landmark discrimination task.
• “Where pathway” in brain because it is critical for spatial relationship

Question 23

Sensory Codes:

Answer 23

Specificity
Distributed: Sparse, Population

Question 24

Specificity code

Answer 24

have a single neuron represent each object

Question 25

Distributed coding

Answer 25

have many groups of neurons represent each object

Question 26

Sparse coding

Answer 26

fewer groups are needed for representation (but always more than a single)

Question 27

Population coding

Answer 27

more groups of neurons in representation

Question 28

Domain Specificity models

Answer 28

• Certain brain regions are dedicated to specific categories of objects [e.g. faces]
• More modularity(particular), less plasticity (can be retrained)
• Generally expect to find sparse codes

Question 29

Property-based models

Answer 29

• Object knowledge is linked to sensory and motor attributes
• Constructivist/ embodied cognition view - less modularity, more plasticity
• Generally expect to find population codes

Question 30

double dissociation

Answer 30

two functions involve different brain mechanisms and operate independently

Question 31

damage to FFA can cause

Answer 31

prosopagnosia