4- Intro to Cones and Color Vision

What is the minimum number of photopigment types required for color vision?

two

What does it mean if a patient cannot adjust every single primary light to match a test light by using one knob?

they are NOT a monochromatic

A dichromat acts as what in an anomaloscope?

monochromat

The anomaloscope tests in what region?

Rayleigh region

A dichromat requires how many knobs to make a match on the anomaloscope?

1 knob

If a patient cannot adjust every mix of primary lights to make a match by only adjusting brightness what are they?

they must be a trichromat

What is the Rayleigh region?

part of the spectrum where S cones are very insensitive and don't really respond (>550nm)

In the Rayleigh region a trichromat behaves as a?

dichromat

What type of patients will reject the normal match on an anomalscope?

rod monochromat

S-cone monochromat

deuteranomolous

protanomalous

A rod monochromat or S-cone monochromat will match the red with what?

darkest yellow

A rod monochromat or S-cone monochromat will match the Green with what?

they WONT match, cannot get yellow bright enough

What is a deuteranope missing?

M cones

What will the deuteranope match the green and red with?

all the same brightness yellow

What is a protanope missing?

L cones

What does a protanope match the red light to?

dim yellow

What does a protanope match a green light to?

a bright yellow

How would a tritanope test in the anomaloscope?

as normal patient

What is deuteranomalous?`

patient has normal L cones and abnormal M cones

What is protanomalous?

patient has normal M cones and abnormal L cones

A deuteranomalous patient will match with?

too much green

A protanomalous patient will match with?

too much red (+darker yellow)

What are metamers?

two different wavelengths of light that appear the same to the observer

What is the best humans can discriminate wavelengths?

<2nm difference

humans are able to best discriminate wavelength at which colors?

1. blue + yellow

2. green

humans are worse at discriminating what colors?

reds

violets

What is the spectrum locus on a CIE diagram?

range of monochromatic light

What is the line of purples?

lights made from mixing reed + violet

What is unique of the line of purples?

colors on the line are non-spectral, meaning no monochromatic light can generate them

What is a confusion line?

lines on a CIE where all the lights that fall on the line are metameric for the color deficient

What is the copunctal point?

the point where all the confusion lines converge