From Photons to Phenomena Flashcards

1
Q

what are inferences and visual perceptions made from?

A

photons

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2
Q

stages of processing

A
  1. reception
  2. transduction
  3. coding
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3
Q

reception

A

physical photon energy hits the retina and interacts with photo receptors

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4
Q

transduction

A

converts physical photon energy into electrochemical pattern sent down the brain

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5
Q

coding

A

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

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6
Q

what are rods?

A

photoreceptors that provide vision in dim light and movement

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7
Q

where are rods?

A

peripheral regions of the retina

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8
Q

what are cones?

A

photoreceptors that provide colour and sharpness of vision

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9
Q

where are cones?

A

found particularly on the fovea

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10
Q

trichromatic theory

A

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

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11
Q

opponent-process theory

A

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

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12
Q

what is colour constancy?

A

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

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13
Q

where do signals from the retina travel down?

A

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

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14
Q

parvocellular pathway

A

most input comes from rods

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15
Q

magnocellular pathway

A

most input comes from cones

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16
Q

pathways between the eye and the brain

A
  1. retina
  2. optic nerve
  3. optic chiasm
  4. lateral geniculate nucleus
  5. cortical area V1
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17
Q

what is receptive field?

A

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

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18
Q

what is retinotopy?

A

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

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19
Q

what is lateral inhibition?

A

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

20
Q

what is the lateral geniculate nucleus part of?

A

the thalamus, involved in sensory input and motor output

21
Q

what does the LGN contain?

A
  • centre-surround receptive field
  • retinotopic map
22
Q

what does the LGN combine?

A

signals across space and time to determine whether objects are moving

23
Q

what does the V1 extract?

A

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

24
Q

what does damage to V1 result in?

A

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

25
functional specialisation theory
different parts of the visual cortex are specialised for different visual functions
26
V1 and V2 function
involved in early visual perception
27
V3 and V3a function
responsive to form and moving objects
28
V4 function
responsive to colour
29
V5/MT function
responds to visual motion
30
what might challenge the idea of distinct visual processing modules?
sighted people do not perceive colour differently however, synchronised temporal coding may explain the conscious experience of object processing
31
where pathway
(dorsal/parietal stream) concerned with movement processing
32
what pathway
(ventral/temporal stream) concerned with colour and form processing
33
damage to dorsal stream
result in optic ataxia
34
damage to ventral stream
results in visual form agnosia
35
stages of object recognition
1. early visual processing 2. perceptual segregation 3. structural depictions 4. attaching meaning to the object based on prior semantic knowledge
36
where is object information processed?
in the ventral visual 'what' stream
37
agnosia
deficits in object recognition without primary visual damage
38
apperceptive agnosia
impairment in constructing perceptual representations from vision
39
what is apperceptive agnosia associated with?
lateral occipital lobe damage
40
associative agnosia
impairment in mapping perceptual representations onto knowledge of object functions
41
what is associative agnosia associated with?
occipital-temporal lobe damage
42
prosopagnosia
impairment in face processing caused by damage further along the ventral stream
43
what may fusiform face area be specialised for?
complex visual processing, as humans are experts at within-category discrimination
44
holistic processing
features of the face are processed less than other types of objects
45
evidence of holistic processing
disruptions in spatial-relational inversion