Vision

Question 1

What is the visible light wavelength spectrum?

Answer 1

390nm - 750nm

Question 2

Rods detect intensity, not wavelength. T/F?

Answer 2

True.

Question 3

Humans are trivariants. T/F?

Answer 3

True.

Question 4

S-cones peak at which wavelength?

Answer 4

440nm

Question 5

M-cones peak at which wavelength?

Answer 5

545nm

Question 6

L-cones peak at which wavelength?

Answer 6

565nm

Question 7

Which two colours are easily confused?

Answer 7

Red and green as they overlap a lot on the spectrum. Blue cones are more isolated so easier to distinguish.

Question 8

What is the Munsell Colour System?

Answer 8

Hue: wavelength
Value: reflectance and luminosity
Chroma: saturation of signal

Question 9

What is the opponent colour theory?

Answer 9

3 channel theory. They are:
red-green
blue-yellow
black-white

Question 10

What is the stage theory?

Answer 10

The modern model of normal colour vision which incorporates both the trichromatic theory and opponent colour theory into two stages.

1. Receptor stage: 3 pigments
2. Neural processing: colour opponency. Post-receptoral.

Question 11

What is a trichromat?

Answer 11

Person with normal colour vision

Question 12

What is a dichromat?

Answer 12

colour blindness. sex linked:
Protanopia: less sensitive to red.
Deuteranopia: less sensitive to green.

Question 13

What is the Ishihara test?

Answer 13

Test with number embedded in dots. Can you see it????

Question 14

What properties allow colour to be perceived?

Answer 14

Intensity and wavelength.

Question 15

In the CIE diagram, what is in the centre of the graph?

Answer 15

White Achromatic Point.

Question 16

Do rods have high light threshold?

Answer 16

No.

Question 17

Of red, green and blue, which to cone types overlap a lot?

Answer 17

red and green.

Question 18

What 3 properties are need to fully specify a colour?

Answer 18

Hue (wavelength), value (lightness and reflectance) and chroma (saturation).

Question 19

What is the trichromatic theory?

Answer 19

A theory based on colour mixing, suggesting a combo of 3 channels explain colour discrimination functions.

Question 20

What is the opponent colour theory?

Answer 20

Suggests there are 3 channels: red-green, blue-yellow and black-white (responding in an antagonist way).

Question 21

What is the colour vision pathway at the level of the RETINA for red-green?

Answer 21

L and M cones -> midget ganglion cells -> parvocellular neurons (LGN).

NB: L or M will be stimulated more than the other.

Question 22

What is the colour vision pathway at the level of the RETINA for blue-yellow?

Answer 22

Blue: S cones -> small bistratified ganglion cells -> koniocellular neurons (LGN).

Yellow: L and M cones together inhibit S cones being stimulated -> small bistratified ganglion cells -> koniocellular neurons (LGN).