wk7: ND - Anomolous Trichromacy

Question 1

What percentage of males have protanomoly?

Answer 1

1%

Question 2

What percentage of males have Deutranomaly?

Answer 2

5%

Question 3

How does the luminosity of red light compare between normal trichromats, protanomals, and deuteranomals?

Answer 3

Normal: is normal, value of 1
Deuteranomals: slightly lower
Protanomals: much lower

Question 4

How does the luminosity of green light in deuteranomals compare to normal?

Answer 4

Slightly lower (is around 0.8 or so compared to 1 for normals)

Question 5

How does the luminosity of green light in protanomals compare to normal?

Answer 5

Slightly higher

Question 6

Is there much variation in the wavelength discrimination for protanomals and deuteranomals?

Answer 6

Yes. They both have much variation between subjects

Question 7

Where is the neutral point for saturation discrimination in protanomals and deuteranamols?

Answer 7

They don’t have a neutral point for saturation discrimination. It’s a trick question haha!

Question 8

Do protanomals and deuteranomals experience more or less saturation of spectral colours compared to normals?

Answer 8

Less, so spectral colours look more desaturated

Question 9

Summarise the colour perception of anomalous trichromats compared to normals in 4 points

Answer 9

Anomalous trichromats see:

1. Metamers differently
2. Fewer colours (poorer wavelength discrimination, and deltaP)
3. Saturated colours appear desaturated (poorer deltaP)
4. PA have reduced luminosity to red (also DA very slightly)

Question 10

What is the function of the Nagel Anomaloscope?

Answer 10

Provides definitive diagnosis of the congenital protan-deutan colour vision defects

Question 11

How does the Nagel anomaloscope work?

Answer 11

It’s a colour matching instrument. One of the knobs controls intensity of the yellow (589nm) sodium field, and the other knob controls the ratio of lithium red (670nm) and mercury green (546nm). Task is to match hemifields

Question 12

How do deuteranomals make matches with yellow?

Answer 12

by adding more green

Question 13

How do protanomals make matches with yellow?

Answer 13

by adding more red

Question 14

How can opsin genes be abnormal/compromised? (4)

Answer 14

Completely missing from gene array
Point mutations
Major sequence/deletions
Unequel crossing over (between M and L cones)

Question 15

What do point mutations in opsin gene lead to?

Answer 15

dysfunctional photopigment. It’s very rare that you’d have a functional photopigment after a point mutation

Question 16

What percentage homologous is the S pigment with M and L pigment?

Answer 16

43% homologous

Question 17

How similar are M and L pigments?

Answer 17

96% mutually identical

Question 18

When adding red/green to match with yellow, will deuteranopes have to change intensity of the yellow?

Answer 18

No. Protanopes will though because the red is less luminous for them and makes the overall mixture dimmer

Question 19

What are Hybrid genes?

Answer 19

Genes created from a mismatch of parent genes from meiosis due to (in this example) multiple copies of the M gene, which make a misalignment more likely

Question 20

How are anomalous trichromats similar but different from normal trichromats?

Answer 20

While they need 3 primaries to match another colour in a colour matching experiment, the matches they make are different from normals. They often reject colour matches made by normals