Lecture 12

Question 1

After showing participants a series of photos with implied motion to one side i.e. left or right for 60 seconds and asking them to identify the direction of movement in an array of moving dots.

Before being ‘adapted’ to the pictures participants were…

Answer 1

equally likely to perceive dots with zero coherence as moving to the right or left

Question 2

After showing participants a series of photos with implied motion to one side i.e. left or right for 60 seconds and asking them to identify the direction of movement in an array of moving dots.

After being ‘adapted’ to the pictures participants were…

Answer 2

more likely to indicate an array of dots with zero coherence was moving in the direction OPPOSITE to which they had been adapted e.g. adapt to pictures with leftward motion, report seeing dots moving to right

Question 3

colour helps us __ and ___ objects

Answer 3

colour helps us classify and identify objects

Question 4

colour facilitates __ ___ of elements into objects

Answer 4

colour facilitates perceptual organization of elements into objects

Question 5

participants were found to identify foods presented in ___ colours more rapidly

Answer 5

participants were found to identify foods presented in natural colours more rapidly

Question 6

3 conclusions from Newton’s experiment with prisms

Answer 6

1) White light is a mixture of all colours

2) Other colours on the spectrum are not mixtures but rather represent ‘pure’ colours (cannot be broken down any further)

3) the fact that the degree to which beams from each part of the spectrum were ‘bent’ by the second prism differed was indicative of a difference in some physical property

Question 7

___ colours (e.g. blue, green, red) are perceived when certain wavelengths are reflected by objects more than others i.e. ___ ___

Answer 7

Chromatic colours (e.g. blue, green, red) are perceived when certain wavelengths are reflected by objects more than others i.e. selective reflection

Question 8

___ colours (gray, black, white) are perceived when light is reflected equally across the spectrum

Answer 8

Achromatic colours (gray, black, white) are perceived when light is reflected equally across the spectrum

Question 9

Reflectance curves

Answer 9

plot percentage of light transmitted at each wavelength

Question 10

Selective transmission

Answer 10

occurs when only certain wavelengths pass through objects, can be plotted with transmission curves

Question 11

Short wavelength reflected or transmitted causes ___ to be perceived

Answer 11

Short wavelength reflected or transmitted causes blue to be perceived

Question 12

Medium wavelength reflected or transmitted causes ___ to be perceived

Answer 12

Medium wavelength reflected or transmitted causes green to be perceived

Question 13

Long and medium wavelengths reflected or transmitted causes __ to be perceived

Answer 13

Long and medium wavelengths reflected or transmitted causes yellow to be perceived

Question 14

Long wavelengths reflected or transmitted causes __ to be perceived

Answer 14

Long wavelengths reflected or transmitted causes red to be perceived

Question 15

Long, medium and short wavelengths together reflected or transmitted causes __ to be perceived

Answer 15

Long, medium and short wavelengths together reflected or transmitted causes white to be perceived

Question 16

Subtractive colour mixing

Answer 16

occurs when mixing together paints that have different pigments

Question 17

Adding more pigments to a mixture results in ___ wavelengths being reflected (and ___ being absorbed)

Answer 17

Adding more pigments to a mixture results in fewer wavelengths being reflected (and more being absorbed)

Question 18

Example: why does a mixture of blue and yellow appear green?

Answer 18

Blue reflects mostly short-wavelength (and some medium), absorbs others. Yellow reflects mostly long-wavelength (and some medium), absorbs others. After being combined, both pigments in the paint picture continue to reflect the same wavelengths they did on their own. Only wavelengths that are reflected from a mixture of blue and yellow are medium wavelengths = green

Question 19

Additive color mixing

Answer 19

occurs when mixing lights of different wavelengths

Question 20

Example: pure blue light projected on a white board and pure yellow light being projected on a white board create perception of __ because the ___ wavelengths of blue, __ and ___ wavelengths being reflected from yellow combine… so short, medium and long wavelengths are all being reflected causing ___

Answer 20

Example: pure blue light projected on a white board and pure yellow light being projected on a white board create perception of white because the short wavelengths of blue, long and medium wavelengths being reflected from yellow combine so short, medium and long wavelengths are all being reflected causing white

Question 21

spectral colours

Answer 21

those that appear on the spectrum

Question 22

non spectral colours

Answer 22

created by mixing spectral colours in various combinations

Question 23

hue

Answer 23

another term for chromatic colour or what we might refer to as a ‘pure’ color

Question 24

value

Answer 24

light-to-dark dimension

Question 25

saturation

Answer 25

determined by the amount of white in a hue

Question 26

desaturation

Answer 26

more white

Question 27

HSV (hue/saturation/value) colour solids

Answer 27

can be used to determine additive colour combinations

Question 28

Trichromatic Theory

Answer 28

states that all human colour vision is based on 3 principle colours (red, green, and blue)

Question 29

‘normal’ colour vision depends on __ receptor mechanisms i.e. __ types of cones

Answer 29

‘normal’ colour vision depends on 3 receptor mechanisms i.e. 3 types of cones

Question 30

Physiological evidence for the Trichromatic theory came from measuring the ___ ___ of visual pigments in receptors in 1960s

Answer 30

Physiological evidence for the Trichromatic theory came from measuring the absorption spectra of visual pigments in receptors in 1960s

Question 31

colour matching experiments show that colours that which are perceptually similar can be caused by different combinations of various physical wavelengths (referred to as ___)

Answer 31

colour matching experiments show that colours that which are perceptually similar can be caused by different combinations of various physical wavelengths (metamers)

Question 32

cone pigment types differ in the ___ of ___ they absorb from particular parts of the visible light spectrum, it is __ an __ or __ response (i.e. not the case that short ones only respond to blue)

Answer 32

cone pigment types differ in the proportion of light they absorb from particular parts of the visible light spectrum, it is not an all or nothing response (i.e. not the case that short ones only respond to blue)

Question 33

One receptor type ___ lead to colour vision because any 2 wavelengths can cause the same response in a ___ (someone with only one cone type) simply by altering the ___

Answer 33

One receptor type cannot lead to colour vision because any 2 wavelengths can cause the same response in a monochromat (someone with only one cone type) simply by altering the intensity

Question 34

principle of univariance

Answer 34

absorption of a photon causes the same effect in all receptors, no matter what the stimulating wavelength is. Once a photon of light is absorbed by a visual pigment molecule, the identity of the light’s wavelength is lost. The only information the neural system encodes/retains is the total amount of light absorbed

Question 35

Example: if 100 photons of 480nm light is absorbed vs 50 photons for 600 nm light in a monochromat person, the __nm light would look twice as brighter than the __ nm i.e. monochromat person __ ___ between these lights

Answer 35

Example: if 100 photons of 480nm light is absorbed vs 50 photons for 600 nm light in a monochromat person, the 480nm light would look twice as brighter than the 600nm i.e. monochromat person can distinguish between these lights

Question 36

herings primary colours:
top half= colours with some degree of ___
bottom half= colours with some degree of ___
right half= colours with some degree of ___
left half = colours with some degree of ___

Answer 36

herings primary colours:
top half= colours with some degree of redness
bottom half= colours with some degree of greeness
right half= colours with some degree of yellowness
left half = colours with some degree of blueness

Question 37

Opponent-processes (3 types)

Answer 37

1. White/ Black
2. red/green
3. yellow/blue

Question 38

Neural mechanisms respond to white/black, red/green, yellow/blue, in an ___ fashion e.g. by increasing excitation (+) in response to red, and increasing inhibition (-) in response to green

Answer 38

Neural mechanisms respond to white/black, red/green, yellow/blue, in an opposing fashion e.g. by increasing excitation (+) in response to red, and increasing inhibition (-) in response to green

Question 39

opponent neurons

Answer 39

respond in an excitatory manner to one end of the spectrum and an inhibitory manner to the other, located in the retina and LGN