Chapter 6: PERCEPTION OF COLOUR

Question 1

What do we call trichromatic coding?

Answer 1

the fact that the eye detects diff colours because it contains 3 types of photoreceptors, each sensitive to a single hue

Question 2

What can genetic defect in colour vision result from?

Answer 2

-Anomalies in one or more of the three types of cones

Question 3

What do people with protanopia see?

Answer 3

they confuse red and green, they see the world in shades of yellow and blue.

Question 4

What do people with deuteranopia see?

Answer 4

also confuse red and green, their vision is dichromatic (two color).

Question 5

What do people with tritanopia see?

Answer 5

difficulty with hues of short wavelength, see the world in greens and reds.

Question 6

How does opponent-colour system work?

Answer 6

• neurons respond to opposing pairs of primary colours
• retina contains two kinds of colour sensitive ganglion cells: red-green, yellow-blue.
• other ganglion cells are black and white detectors.

Question 7

what is a negative afterimage?

Answer 7

The image seen after a portion of the retina is exposed to an intense visual stimulus, consists of colours complementary to those of the physical stimulus.

Question 8

What does the parvocellular system receives information from ?

Answer 8

only from red and green cones

Question 9

What is the role of the extrastriate cortex in the perception of color?

Answer 9

-conveys info about colour from the parvocellular and koniocellular systems along the ventral stream to the inferior temporal lobe.

Question 10

What resolution do cells in the parvocellular system show?

Answer 10

high spatial resolution and low temporal resolution

Question 11

Does the koniocellular system provide information about fine details?

Answer 11

No

Question 12

What can we say about neurons in the magnocellular system?

Answer 12

They are colour-blind.

Question 13

What can lesions of a restricted region of the extrastriate cortex cause?

Answer 13

loss of colour vision without disruption of visual acuity

Question 14

What colour info does the dorsal stream of the extrastriate cortex receive?

Answer 14

mostly magnocellular input (light/dark contrast and movement)

Question 15

What colour info does the ventral stream of the extrastriate cortex receive?

Answer 15

equal input from the magnocellular, parvocellular (red and green cones) and koniocellular systems (blue cones).