From Photons to Phenomena

Question 1

what are inferences and visual perceptions made from?

Answer 1

photons

Question 2

stages of processing

Answer 2

1. reception
2. transduction
3. coding

Question 3

reception

Answer 3

physical photon energy hits the retina and interacts with photo receptors

Question 4

transduction

Answer 4

converts physical photon energy into electrochemical pattern sent down the brain

Question 5

coding

Answer 5

one-to-one correspondence between the physical stimulus and firing pattern of brain neurones

Question 6

what are rods?

Answer 6

photoreceptors that provide vision in dim light and movement

Question 7

where are rods?

Answer 7

peripheral regions of the retina

Question 8

what are cones?

Answer 8

photoreceptors that provide colour and sharpness of vision

Question 9

where are cones?

Answer 9

found particularly on the fovea

Question 10

trichromatic theory

Answer 10

argues there must be three types of colour receptors in the human eye, as primary colours can produce all colours of the spectrum

Question 11

opponent-process theory

Answer 11

inputs from cones are processed in an opposition manner, along scales at the level of neurones

Question 12

what is colour constancy?

Answer 12

the tendency for a surface to appear the same colour, regardless of a change in wave lengths

Question 13

where do signals from the retina travel down?

Answer 13

the optic nerve via two parallel pathways
- parvocellular pathway
- magnocellular pathway

Question 14

parvocellular pathway

Answer 14

most input comes from rods

Question 15

magnocellular pathway

Answer 15

most input comes from cones

Question 16

pathways between the eye and the brain

Answer 16

1. retina
2. optic nerve
3. optic chiasm
4. lateral geniculate nucleus
5. cortical area V1

Question 17

what is receptive field?

Answer 17

region of sensory space within which light will cause the neurone to fire

Question 18

what is retinotopy?

Answer 18

things near to each other in space are processed in cells close together

Question 19

what is lateral inhibition?

Answer 19

reduced activity in one neurone caused by a neighbouring neurone, to enhance object contrast

Question 20

what is the lateral geniculate nucleus part of?

Answer 20

the thalamus, involved in sensory input and motor output

Question 21

what does the LGN contain?

Answer 21

• centre-surround receptive field
• retinotopic map

Question 22

what does the LGN combine?

Answer 22

signals across space and time to determine whether objects are moving

Question 23

what does the V1 extract?

Answer 23

low-level information from the visual scene for later stages of processing

Question 24

what does damage to V1 result in?

Answer 24

cortical blindness, but patients can make blindsight judgements in the “blind” area

Question 25

functional specialisation theory

Answer 25

different parts of the visual cortex are specialised for different visual functions

Question 26

V1 and V2 function

Answer 26

involved in early visual perception

Question 27

V3 and V3a function

Answer 27

responsive to form and moving objects

Question 28

V4 function

Answer 28

responsive to colour

Question 29

V5/MT function

Answer 29

responds to visual motion

Question 30

what might challenge the idea of distinct visual processing modules?

Answer 30

sighted people do not perceive colour differently

however, synchronised temporal coding may explain the conscious experience of object processing

Question 31

where pathway

Answer 31

(dorsal/parietal stream)

concerned with movement processing

Question 32

what pathway

Answer 32

(ventral/temporal stream)

concerned with colour and form processing

Question 33

damage to dorsal stream

Answer 33

result in optic ataxia

Question 34

damage to ventral stream

Answer 34

results in visual form agnosia

Question 35

stages of object recognition

Answer 35

1. early visual processing
2. perceptual segregation
3. structural depictions
4. attaching meaning to the object based on prior semantic knowledge

Question 36

where is object information processed?

Answer 36

in the ventral visual ‘what’ stream

Question 37

agnosia

Answer 37

deficits in object recognition without primary visual damage

Question 38

apperceptive agnosia

Answer 38

impairment in constructing perceptual representations from vision

Question 39

what is apperceptive agnosia associated with?

Answer 39

lateral occipital lobe damage

Question 40

associative agnosia

Answer 40

impairment in mapping perceptual representations onto knowledge of object functions

Question 41

what is associative agnosia associated with?

Answer 41

occipital-temporal lobe damage

Question 42

prosopagnosia

Answer 42

impairment in face processing caused by damage further along the ventral stream

Question 43

what may fusiform face area be specialised for?

Answer 43

complex visual processing, as humans are experts at within-category discrimination

Question 44

holistic processing

Answer 44

features of the face are processed less than other types of objects

Question 45

evidence of holistic processing

Answer 45

disruptions in spatial-relational inversion