Visual Perception

Question 1

what are the 2 visual receptors cells int he retina ?

Answer 1

1. cones

2. rods

Question 2

what do cones do in the retina and where are they located?

Answer 2

• colour and detail perception

- most located in the fovea

Question 3

what do rods do in the retina and where are they located?

Answer 3

• vision in dim light

- located in the periphery

Question 4

what do retinal ganglion cells receive input from a few _____ or hundreds of _____

Answer 4

cones and rods

Question 5

from the retina to the optic nerve, where do signal go to?

Answer 5

Lateral Geniculate Nucleus

Question 6

what does LGN stand for?

Answer 6

Lateral Geniculate Nucleus - comes after the optic nerve when sending visional information to the brain

Question 7

what are the 2 pathways in the retina-geniculate-striate system?

Answer 7

1. Parvocellular (P) Pathway

2. Magnocelluar (M) Pathway

Question 8

Retina-geniculate-striate system: parvocellar (P) pathway

Answer 8

sensitive to colour and fine detail

- most input from cones

Question 9

Retina-geniculate-striate system: magnocelluar (M) pathway

Answer 9

sensitive to motion

- most input from rods

Question 10

where is he right visual field processed in the brain

Answer 10

left hemisphere

Question 11

where is he left visual field processed in the brain

Answer 11

right hemisphere

Question 12

what increases contrast of edges

Answer 12

lateral inhibition

Question 13

what is V1 and V2?

Answer 13

V1 = primary visual cortex
V2 = secondary visual cortex

Question 14

form (shape) processing which V’s?

Answer 14

V1, V2, V3, V4 = all process object shape and form

Question 15

neurons in which cortex response to specific semantic categories (e.g., animals, body parts)?

Answer 15

inferotemporal cortex

Question 16

neurons in which cortex respond to 3D object shape?

Yamane et al., 2008

Answer 16

inferotemporal

Question 17

where does colour processing happen?

Answer 17

V4

Question 18

what is achromatopsia?

Answer 18

no colour perception - found that brain area close to V4 was damaged in nearly all cases

Question 19

Goddard et al (2011)

Answer 19

V4 activation with full-colour movie clips compared to black & white

Question 20

V4 TMS

Answer 20

reduce colour processing performance in V4

Question 21

what V areas is associated with motion processing

Answer 21

V5 (Medial Temporal cortex)

Question 22

the binding problem: feature integration theory (Treisman)

Answer 22

= selective attention plays a role - what we attend to we bind together and things that we don’t, don’t

Question 23

the binding problem: binding-by-synchrony

Answer 23

all the stimuli from one object fire in synchrony to allow the brain understand its all one object

Question 24

what does the dorsal pathway do?

Answer 24

identifying where a certain object is

Question 25

what does the ventral pathway do?

Answer 25

naming what an object is

Question 26

What stream is part of the M pathway and what stream is part of P pathway = both in primary sensory cortex (v!)

Answer 26

Dorsal stream = M pathway = motion processing | Ventral Stream = P pathway = form and colour processing

Question 27

what is The Muller-Lyer illusion

Answer 27

visual illusion - 2 lines the same length but arrows are different

Question 28

what is trichromatic theory

Answer 28

the human retina contains three different receptors for colour (meaning each one is most sensitive to one colour): one is most sensitive to red, one is most sensitive to green, and one is most sensitive to blue. These colour receptors combine the colours to produce the perception of virtually any colour.

Question 29

what is the opponent-process theory

Answer 29

The opponent colour process works through a process of excitatory and inhibitory responses, with the two components of each mechanism opposing each other.

Question 30

what is dual process theory

Answer 30

combination of trichromatic and opponent process theory

Question 31

what is colour constancy

Answer 31

an object appearing one colour despite multiple shades of the colour due to illumination

Question 32

what is binocular disparity in depth perception

Answer 32

the slight difference between the right and left retinal images. When both eyes focus on an object, the different position of the eyes produces a disparity of visual angle, and a slightly different image is received by each retina.

Question 33

what is size constancy

Answer 33

the tendency for objects to appear the same size whether their size in the retinal image is large or small

Question 34

size perception and memory

Answer 34

size perception of objects depends on memory of their familiar size rather than on perceptual information

Question 35

what is blindsight?

Answer 35

perception without awareness = patients state they can't see anything but they respond to visual stimuli sitmlui is sent directly to V5 (motion detection centre) but no conscious recognition of it