Perception 2

Question 1

Define visible light

Answer 1

Band of energy within the electromagnetic spectrum

Question 2

What are different wavelengths of light associated with?

Answer 2

Different colour perceptions

Question 3

What does light consist of?

Answer 3

Small packets of energy called photons

Question 4

What is light intensity (luminance) associated with?

Answer 4

Perception of brightness

Question 5

What is it called when photons collide with particles of matter?

Answer 5

Absorption

Question 6

What is it called when light strikes opaque surfaces?

Answer 6

Reflection

Question 7

What is it called when light passes through transparent matter?

Answer 7

Transmission

Question 8

What does the eye use to project an image onto the retina?

Answer 8

Uses convex cornea and lens

Question 9

What does directional sensitivity represent?

Answer 9

The spatial structure rather than sum total of light

Question 10

What transducer light into an electrical potential?

Answer 10

Photoreceptors

Question 11

What does the electrical potential in the eye reach when it flows through a network of neutrons?

Answer 11

Retinal ganglion cells

Question 12

After the retinal ganglion cells, where does the electric potential go?

Answer 12

Back out the eye via the optic nerve

Question 13

Where are rods located?

Answer 13

Peripheral retina

Question 14

What are rods capable of?

Answer 14

Operating in low light levels

Question 15

What is concentrated in the centre of the retina?

Answer 15

Cones

Question 16

What requires higher light levels to respond?

Answer 16

Cones

Question 17

What has 3 different photopigments, sensitive to short, medium and long wavelengths of light?

Answer 17

Cones

Question 18

What is the main pathway of visual info from the retina to the brain?

Answer 18

Retina> optic nerve> optic chiasm> Lateral Geniculate Nucleus > primary visual cortex

Question 19

What is light intensity related to?

Answer 19

Perceived brightness

Question 20

Regarding bottom-up theories, what does the retina not record?

Answer 20

Light intensities

Question 21

What does the bottom-up theory suggest?

Answer 21

Responses are shaped by processes occurring within the retina (light/ dark adaptation and lateral inhibition)

Question 22

What does the top-down theory suggest?

Answer 22

The brain uses knowledge about how light interacts with objects when determining perceived brightness

Question 23

What is perceiving a familiar object as having the same brightness under different conditions of illumination?

Answer 23

Brightness constancy

Question 24

Is the sensitivity of the retina constantly adjusted to compensate for changes in mean luminance?

Answer 24

Yes

Question 25

When is sensitivity reduced in the retina?

Answer 25

When the mean intensity of the image is high (visa versa)

Question 26

What does the retina encode?

Answer 26

Contrast

Question 27

Define lateral inhibition

Answer 27

Early form of info processing in retina- retinal ganglion cells receive both excitatory and inhibitory input from neighbouring photoreceptors

Question 28

What is arranged in a centre-surround configuration across the retinal image?

Answer 28

the retinal ganglion cells in the retina

Question 29

What does lateral inhibition do?

Answer 29

Makes the visual system sensitive to changes in luminance

Question 30

What happens in your eyes when looking at the Herman grid illusion?

Answer 30

The intersections are surrounded by more high intensity (white). This results in more inhibition from the surround in on-center, off-surround receptive fields

Question 31

Regarding top-down influences, how to we perceive the Checker-shadow illusion?

Answer 31

Our visual systems use knowledge of how light interacts with 3D objets when determining brightness

Question 32

Why does the world appear in lacking of colour under low-light conditions?

Answer 32

Only rod photoreceptors are sensitive enough to operate, of which contain a single type of photopigment (rhodopsin). Light of different wavelengths can elicit identical responses, making it impossible to accurately signal different wavelengths

Question 33

What are S-cones?

Answer 33

Cones that are preferentially sensitive to short wavelengths (blue cones)

Question 34

What are M-cones?

Answer 34

Cones that are preferentially sensitive to middle wavelengths (green cones)

Question 35

What are L-cones?

Answer 35

Cones that are preferentially sensitive to long wavelengths (red cones)

Question 36

What does the relative outputs of the 3 cone types allow?

Answer 36

Unambiguous signalling of wavelength

Question 37

What is Monochromacy?

Answer 37

When individuals have 0 or 1 functioning cones type, resulting in complete colour blindness (extremely rare)

Question 38

What is Dichromacy?

Answer 38

When one has only 2 functioning cone types

Question 39

What is Protanopia?

Answer 39

When one is missing L-cones

Question 40

What is Deuteranopia?

Answer 40

When one is missing M-cones

Question 41

What is Tritanopia?

Answer 41

When one is missing S-cones

Question 42

What is Anomalous trichomacy?

Answer 42

Defect in one of the cone types- more common form of colour perception deficiency

Question 43

What is Protanomaly?

Answer 43

L-cone deficit

Question 44

What is Deuteranomoly?

Answer 44

M-cone deficit

Question 45

What is Tritanonomaly?

Answer 45

S-cone deficit

Question 46

How is Anomalous trichromacy commonly assessed?

Answer 46

Ishihara Colour test

Question 47

What is Colour opponency?

Answer 47

When retinal ganglion cells receive excitatory and inhibitory input from different cone types- resulting in distinct Red/Green and Blue-Yellow pathways

Question 48

How can colour opponent be demonstrated?

Answer 48

By using negative afterimages

Question 49

Explain colour opponency in relation to red and green

Answer 49

Adaption to red causes a reduction in the sensitivity of long wavelength cones, creating an imbalance in the inputs to red/green opponent retinal ganglion cells

Question 50

Define colour constancy

Answer 50

The tendency for the perceived colour of objects to remain the same, even if the lighting changes

Question 51

How do we try to achieve colour constancy?

Answer 51

By accounting for the intensity and composition of light hitting different surfaces