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Cognitive psyc > week 3 - from photos to phenomena > Flashcards

week 3 - from photos to phenomena Flashcards

1
Q

from eye to cortex

A

1) reception

2) transduction

3) coding

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2
Q

from eye to cortex
1) reception

A

absorption of physical energy (photons)
hits the retina and interacts with photoreceptors

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3
Q

from eye to cortex
2) transduction

A

physical energy converted into an electrochemical pattern
(done by photoreceptors)

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4
Q

from eye to cortex
3) coding

A

electrochemical pattern sent to the brain
one-to-one correspondence between aspects of the physical stimulus and aspects of the resultant nervous system activity

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5
Q

the eye and the retina
cones

A

colour, vision, sharpness of vision

6 million in retina
most in the FOVEA (the place where you are looking)

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6
Q

the eye and the retina
rods

A

vision in dim light and movement

125 million in outer regions of retina (peripherals)

no real colour processing in the periphery

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7
Q

perception is a….

A

constructive process

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8
Q

colour vision
visible light

A

electromagnetic spectrum
human eye most sensitive to the green range

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9
Q

colour vision
trichromatic theory

A

thomas young 1802
all colours by mixing the 3 primary colours

hermann von halmholtz - 3 types of colour receptor in human eye
- short (blue)
- medium (yellow-green)
- long (red)

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10
Q

colour vision
opponent-process theory

A

hering 1878
sighted people dont see eg blueish yellow

colour perception assumed to have three opponent processes
dual process theory (hurvick + jameson, 1957) linked these processes to combinations of inputs from the 3 cone types
- inputs from 3 different cones are processed in an opposition manner
- the difference between cones = different electrical signal

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11
Q

colour vision
colour consistency

A

the tendency for a surface to appear to have the same colour despite a change in the wavelengths contained in the light sauce
- evolutionarily helpful (sun)
——-> top-down influences

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12
Q

after the retina
what happens?

A

signals travel down two parallel pathways

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13
Q

after the retina
what are the two pathways?

A

parvocellular (P) pathway

magnocellular (m) pathway

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14
Q

after the retina
parvocellular (p) pathway

A

sensitive to colour and fine detail
most input from cones

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15
Q

after the retina
magnocellular (m) pathway

A

most sensitive to motion
most input from rods

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16
Q

after the retina
which direction do the pathways travel

A

info goes down optic nerve towards the back of the brain down the p and m pathways

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17
Q

the pathway from the eye to the brain
stages

A

retina —> optic nerve —> optic chiasm —> lateral geniculate nucleus (GN) —> cortical ares V1 (the primary visual cortex)

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18
Q

the pathway from the eye to the brain
direction of signal

A

the signals reaching the left visual cortex come from the left SIDE of the TWO retinas
(cross over at chiasm)
see notes for diagram

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19
Q

properties of visual neurons
retinotopy

A

things that are near each other are processed in cells physically near each other

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20
Q

properties of visual neurons
receptive fields

A

the region of the sensory space (ie retina) within which light will cause the neuron to fire

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21
Q

properties of visual neurons
lateral inhibition

A

a reduction of activity in one neuron that is caused by a neighbouring neuron
useful for enhancing contrast at the edges of objects

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22
Q

lateral geniculate nucleus

A

part of the thalamus
cells have a centre-surround receptive field
–> responds to different light
maintains a retinotopic map
correlates signals from the retina in space and time
—> rapid perception of if something is moving

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23
Q

primary visual cortex (V1)

A

back of the brain
extracts basic into from visual scene
sends info to later stages of processing
maintains retinotopy

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24
Q

primary visual cortex (V1)
single cell recordings

A

hubel and wiesel, 1979
- indicates some cells respond to simple features and others combine those features into more complex ones

25
Q

damages to V1?

A

blindsight
patient cannot consciously report objects presented in this region of space (cortical blindness)

26
Q

visual processing beyond V1

A

info sent one step to next (hierarchal)
to recognise the range of evidence for distinct visual processing modules

27
Q

visual processing beyond V1
functional specialisation theory

A

zeki, 1992, 1993
different parts of visual cortex specialised for different visual functions

28
Q

visual processing
stages
V1+V2

A

early stage of visual perception
eg, shapes

29
Q

visual processing
stages
V3 + V3a

A

responsive to form
(moving objects)

30
Q

visual processing
stages
V4

A

colour

31
Q

visual processing
stages
V5 / MT

A

visual motion

32
Q

visual processing beyond V1
functional specialisation theory
central assumption by zeki

A

colour, form and motion processed in anatomically separate parts of the visual cortex
brain imaging (PET position emission tomography) study - in humans
- V4 more active for coloured than greyscale images
- V5 more active for moving than static dots

33
Q

V4 - colour centre of the brain
cortical achromatopisa

A

cant see colours due to V4 damage (macaque monkeys)
(also V2 and V3 - despite working retina)
can perceive things they know the colour of (implicit colour processing)
link not perfect

34
Q

V5 / MT - motion centre
akinetopsia

A

damage = akintetopsia
patient LM
- bilateral damage to V5
- good at looking at stationary objects
- good colour vision
- motion perception grossly deficient

35
Q

challenge for functional specialisation

A

the binding problem
colour not separate to shape
how are different features bound together?

36
Q

the binding problem
possible solution

A

coherent perception depends on synchronised neural activity between brain areas (attention needed)

37
Q

beyond visual cortex
parietal (dorsal) pathway

A

where pathway
movement processing

along top of brain

38
Q

beyond visual cortex
temporal (ventral)

A

what pathway
colour and form processing

along bottom of brain

39
Q

vision for perception / vision for action

A

patient DF
lesion to lateral occipital cortex (what pathway)
trouble locating and identifying objects
however pereption fine (has where)
letter box task
- cant match
- can put through

40
Q

object recognition
a model

A

1) early visual processsing (V1, V2, V3, V4, V5/MT)
2) perceptual segregation - grouping of visual elements
3) structural descriptions - matchiing grouped visual description onto a representation of the object stored in the brain
4) attaching meaning to an object - based on prior knowledge

41
Q

object recognition
2) perceptual segregation

A

seperatiing visual input into individual objects
thought to occur before object recognition

42
Q

Gestalt psychology
fundamental priciple

A

law of Pragnaz
perceieve whats in front of you as the simplest possible solution

assumes a set of rule sthat operate early in visual processing

43
Q

Gestalt law of perecptual organismation

A

1) law of prosmimity
2) law of similarity
3) law od good continuation
4) law of closure

44
Q

figure - ground segregation

A

faces
goblet illusion
- on in front of the other
assume figure > ground

45
Q

Gestalt problems

A

segmentations processes not always bottom up
- x in letters or shape
- faster to fidn x if in letter because we know letterrs
- so top-down influences
most evidence descriptive
relies heavily on introspection and evidence from 2D drawings

46
Q

object recognition and the brain
where?

A

happens in temporal (what) pathway

47
Q

object recognition and the brain
object recognition deficits
AGNOSIA

A

impairment in object recognition
different kinds of impairments depending on where in pathways

48
Q

object recognition and the brain
object recognition deficits
APPERCEPTIVE AGNOSIA

A

impairment in process which constructs a perceptual representation
seeingn parts on whole
lateral occipital lobe damage (the side)
paient HSA (1987) –> bilateral ventral medial occipital damage
- can recognise from touch
seeing paintbrush seperately
cannot group objects

49
Q

object recognition and the brain
object recognition deficits
ASSOCIATIVE AGNOSIA

A

impairment in teh process which maps a visual representation onto knowledge of the objects function
seeing the whole thing but not knowing its meaning
occipio-temporal damage (where occipital and temporal lobe meet)
Patient LH: can copy drawings but cannot name them

conisitant with a hierarchal multistage process

50
Q

object recognition and the brain
object recognition deficits
APPEREPTIVE OR ASSOCIATIVE AGNOISA further along temporal pathway?

A

associative agnoia is further along

51
Q

cultural differenes and biases in psychological research data

A

most from white western researchers and participants
cukture plays a significant role
- westerners prioritise processing / categorising objects
- east asians proitise relationships between objects
sso cant assume psychological “truths” apply to all humanity

52
Q

the problem with faces

A

is a within category discrimination (look similar)
other objects recognition is between categories
different type of processing altogether?

53
Q

are faces special?
neuropsychological evidence

A

propsopagnosia
impairment of face processing (late stage –> for V1 ect)
de renzi (1986) patient cant recognise families faces but can by clothes and voice
impairment at the stage of matching to stored info

54
Q

are faces special?
neuroscience evidence

A

fusiform face area -> underside of temporal love
part of ventral stream
responds to faces more than other objects (in functional imaging)

55
Q

why are faces special

A

just more difficult?
holistic / contijural processing ?
visual expertise ?
domain specificty

56
Q

why are faces special
holistic processing

A

relationship between features
features of faces are processed less than other types of objects (eg homes)
upsidedown objects
- face recognition distruped by inversion
sighted people tend to recognise upsidedown faces slower
typrically interpreted as evidecne for holistic processing

57
Q

why are faces special
visual expertise

A

have become experts because within category discriminations
- greeble discrimination (1999+2000)
- can learn a good level of Greeble distinction
- make use of fusiform face area
so perhaps fusiform face area for complex visual processing (not just faces)

58
Q

why are faces special
visual expertise
critisms

A

not all prosopagnosic patients are impaired at within category discrimination
WJ: flock of sheep
RM: miniture cars
so not just fusiform face area needed for this

Cognitive psyc (23 decks)

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