S2W3 - Vision

Question 1

Characteristics of rods

Answer 1

Perceive dim light; scotopic; no colour perception; many grouped onto a retinal ganglion cell

Question 2

Characteristics of cones

Answer 2

Perceive bright light; photopic; colour perception; single cone connected (indirectly) to retinal ganglion cell

Question 3

Which area has only cones and no rods?

Answer 3

The fovea

Question 4

Where is the blind spot, and why can’t we see it?

Answer 4

Where the optic nerve is; No retinal receptors in that area; Our brains “fill in” that gap in our vision with previous knowledge

Question 5

3 main types of cells in the retina

Answer 5

Receptor (rod and cone); Bipolar: Retinal Ganglion

Question 6

Characteristics of amacrine cells

Answer 6

Receive information from bipolar cells and interact with bipolar and retinal ganglion cells

Question 7

Characteristics of horizontal cells

Answer 7

Receive information from receptors and adjust signals sent to bipolar cells, also regulate activity in the receptors

Question 8

Pathway from the eye to V1

Answer 8

Optic nerve; optic chiasm; optic tract; thalamus, lateral geniculate nucleus; optic radiations; V1

Question 9

Achromatopsia

Answer 9

damage to V4; inability to (consciously) perceive colour with no damage to the cones in the eye

Question 10

Akinetopsia

Answer 10

damage to V5; inability to perceive (consciously) perceive motion; motion appears as a series of static images

Question 11

What degree do you find the most rods?

Answer 11

20˚ on the nasal and temporal side

Question 12

What degree range is the blind spot?

Answer 12

~12-18˚ on the nasal side

Question 13

Purkinji effect

Answer 13

Scotopic vision peaks at 560nm ∫, photopic peaks at 500nm ∫, therefore, green/blue light appears brighter in dim light and red/yellow light appears brighter in sunlight

Question 14

Trichromatic colour theory

Answer 14

We perceive only 3 colours, and interpret others from there
S, blue, 420nm ∫
M, green, 540nm ∫
L, red, 570nm ∫

Question 15

Opponent process theory

Answer 15

Excititory and inhibitory cells interact to produce colours that are either one colour or its negative
Red/green vs blue/yellow

Question 16

Rhodopsin (active)

Answer 16

Is a pigment molecule
Activates with scotopic vision; sodium channels close; rod becomes hyperpolarised; limits release of glutamate (which is inhibitory)

Question 17

Dorsal stream (V)

Answer 17

Moves towards parietal lobe
“Where”
Control of behaviour

Question 18

Ventral stream (V)

Answer 18

Moves towards temporal lobe
“What”
Conscious perception

Question 19

Stereotopic Vision

Answer 19

Your left and right eye see two different images, but your brain combines into a single percept

Question 20

Uncrossed disparity is

Answer 20

the point further from your focus
you must uncross your eyes to put it in focus

Question 21

Crossed disparity is

Answer 21

the point nearer to you from your focus
you must cross your eyes to put it in focus

Question 22

Pulfrich illusion

Answer 22

SETUP: Eyes follow a left to right oscillating object with a filter over one eye.
ILLUSION: You perceive the object as moving along a oliptical path (rather than straight path)
REASON: your filtered eye is delayed in following the object, and this misalignment results in a disparity that your brain will try to rectify with stereotopic vision

Question 23

Motion parallax

Answer 23

As the amount you see increases by the distance squared, objects in motion that are further away appear to move slower than that which is closer
i.e. a moving object 5m from the face appears to be moving 4x faster than an object at 10m and 9x faster than an object at 15m (2^2 and 3^2, respectively)

Question 24

Monocular Depth

Answer 24

being able to interpret depth with cues beside stereovision

Question 25

Occlusion

Answer 25

one object behind another object will obstruct the view

Question 26

Retinal size

Answer 26

the physical size of the object on the retina (i.e. bigger is probably closer)

Question 27

linear perspective

Answer 27

convergence of points in an image for scale

Question 28

Texture gradient

Answer 28

More texture/ details = closer to eyes

Question 29

Light/ Rayleigh Scatter

Answer 29

Farther things appear more blue as blue light can travel father distances