w2 Flashcards

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1
Q

what is reception

A

Absorption of physical
energy – i.e. photons

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2
Q

what is transaction

A

Physical energy is
converted into an
electrochemical pattern
in the neurons

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3
Q

what is coding

A

One-to-one correspondence
between aspects of the physical stimulus and aspects of the resultant
nervous system activity

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4
Q

what element of vision involves rods

A

light and movement

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5
Q

what element of vision involves cones

A

colour and sharpness

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6
Q

where are the majority of cones located

A

the fovea

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7
Q

where are most rods located

A

outer regions of the retina

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8
Q

what colour range is human eye most sensitive to

A

green range

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9
Q

Hermann von Helmholtz
then proposed that…

A

there must be three types of
colour receptors in the
human eye, responding to
different wavelengths of
light

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10
Q

what did Thomas Young find

A

all colours of the
spectrum can be produced
by mixing 3 primary colours

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11
Q

what colour is short wavelength

A

blue

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12
Q

what colour is medium wavelength

A

yellow/green

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13
Q

what colour is long wavelength

A

red

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14
Q

what level does opponent-process theory work at

A

neurons

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15
Q

what is colour constancy

A

The tendency for a surface to appear to have the same colour despite a
change in the wavelengths contained in the illuminant

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16
Q

what are the 2 pathways after the retina

A

Parvocellular (P) Pathway
Magnocellular (M) Pathway

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17
Q

what is the P pathway sensitive to

A

Sensitive to colour and fine detail

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18
Q

which pathway has most input from cones

A

P pathway

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19
Q

what is the M pathway sensitive to

A

Most sensitive to motion

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20
Q

which pathway has the most inout from rods

A

M pathway

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21
Q

what are the steps in the pathway from the eye to the brain (5)

A
  1. Retina 2. Optic nerve 3. Optic chiasm
  2. Lateral Geniculate Nucleus (LGN) 5. cortical area V1
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22
Q

what is a receptive field

A

The region of the sensory space (i.e. retina) within which light will cause the neuron to fire

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23
Q

what is retinotopy

A

Things that are near to each
other in space are processed
in cells that are physically
near to one another

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24
Q

what is lateral inhibition

A

A reduction of activity
(inhibition) in one neuron
that is caused by a
neighbouring neuron

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25
Q

why is lateral inhibition useful

A

Useful for enhancing
contrast at edges of
objects

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26
Q

what does LGN stand for

A

Lateral Geniculate
Nucleus

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27
Q

what is LGN part of

A

the thalamus

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28
Q

what is the thalamus

A

a subcortical relay for most of the
brain’s sensory input and motor outpu

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29
Q

what do cells in the LGN have

A

a centre-surround receptive field

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30
Q

what does the centre-surround receptive field in LGN cells do

A

Responds to differences in light across their receptive field

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31
Q

what are the roles of the LGN

A
  • Responds to differences in light across their receptive field
  • maintains a retinotopic map
  • correlates signals from the retina in space and time
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32
Q

what are the roles of V1 (the primary visual cortex)

A
  • Extracts basic information from the visual scene
  • send this information for stages of processing
  • maintains retinotopy
33
Q

what did single-cell recordings by Hubel and Wiesel (1979) indicate

A

in V1, some cells respond to simple features, and others combine those features into more complex ones

34
Q

what does damage to V1 lead to

A

cortical blindness

35
Q

what is cortical blindness

A

the patient cannot consciously report
objects presented in this region of
space

36
Q

what can a patient with cortical blindness still do

A

the patient is still able to
make some visual discriminations in
the “blind” area

37
Q

with cortical blindness, why is the patient is still able to
make some visual discriminations in
the “blind” area

A

there are other
routes from the eye to the brain

38
Q

what is blindsight

A

Filling-in of ‘blind’ regions similar to filling-in of normal blind spot

39
Q

what does the functional specialisation theory suggest

A

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

40
Q

V1 and V2 role

A

Early stage of visual perception (e.g.
shapes)

41
Q

V3 and V3a role

A

Responsive to form (especially of moving objects)

42
Q

V4 role

A

Responsive to colour

43
Q

V5/MT role

A

Responsive to visual motion

44
Q

who created functional specialisation theory

A

Zeki

45
Q

what is the central assumption of functional specialisation theory

A

that colour, form, and motion are
processed in anatomically separate parts of the visual cortex

46
Q

what did Zeki (1991) do

A

a brain imaging (PET) study

47
Q

what did Zeki (1991) find about human V4

A

V4 more active for coloured than greyscale images- specialised for colour

48
Q

what did Zeki (1991) find about human V5

A

V5 more active for moving dots
compared with static dots- specialised for motion

49
Q

what is cortical achromatopsia

A

patients can’t see colour due to damage to V4, V2, or V3, despite a fully functioning retina

50
Q

what do case studies of patients with cortical achromatopsia indicate

A

Case studies indicate intact implicit
colour processing in patients with
achromatopsia

51
Q

what do we conclude from case studies of patients with achomatopsia

A

V4 is involved in colour
processing but the link between
colour processing and V4 is not
perfect

52
Q

what is V5/MT involved with

A

motion processing in brain imaging studies of humans

53
Q

what does damage to V5/MT lead to

A

akinetopsia

54
Q

what could a patient with akinetopsia do/ not do

A
  • can locate stationary objects
  • can detect colour
  • motion perception deficient
55
Q

what is the binding problem

A

Sighted people don’t perceive the colour of things separately to
their shape, but in your brain those things are processed
separately… so where in the brain is the thing that is perceived?

56
Q

what is the parietal (dorsal) pathway

A

the where pathway, concerned
with movement processing

57
Q

what is the temporal (ventral) pathway

A

the what pathway, concerned with colour and form processing

58
Q

what are the steps of the model of object recognition

A
  1. Early visual processing (colour,
    motion, edges etc.)
  2. Perceptual segregation: Grouping of
    visual elements (Gestalt principles,
    figure–ground segmentation)
  3. Matching grouped visual description
    onto a representation of the object
    stored in the brain (called structural
    descriptions)
  4. Attaching meaning to the object
    (based on prior semantic knowledge)
59
Q

what is perceptual segregation

A

Separating visual input into individual
objects

60
Q

when does perceptual segregation occur

A

Thought to occur before object
recognition

61
Q

what are the 4 Gestalt Laws of Perceptual Organisation

A

a) The law of proximity
b) The law of similarity
c) The law of good
continuation
d) The law of closure

62
Q

issues with gestalt psychology

A
  • Most evidence only descriptive, not explanatory
  • Relies heavily on introspection and
    evidence from 2D drawings
  • Some segmentation clearly occurs via
    top-down prior knowledge
63
Q

what is agnosia

A

impairment in object recognition
(without primary visual
deficits)

64
Q

what is apperceptive agnosia

A

Impairment in the process which constructs a perceptual representation from vision, can see parts but not the whole

65
Q

what is apperceptive agnosia involved with

A

ateral occipital lobe damage

66
Q

what is associative agnosia

A

Impairment in the process which maps a perceptual representation onto knowledge of the objects functions and associations, seeing the whole but not its meaning

67
Q

what is associative agnosia involved with

A

occipito-temporal damage

68
Q

when shown a drawing of an object, what would a patient with associative agnosia be able to do

A

preserved ability to
copy drawings of objects, but unable to
name them or show what they are fo

69
Q

what are issues with research into object perception

A
  • most Psych research comes from white male Western researchers and participants
  • Westerners prioritise processing / categorising objects, while East Asians prioritise the relationships between objects and context
70
Q

lesions to different areas of the brain in the ventral visual stream leads to

A

agnosia for different types
of objects

71
Q

why are faces different to other objects

A

Face recognition is a within-category
discrimination (all faces look very similar), whereas other objects are between-category discrimination

72
Q

why may facial recognition be different to other object discrimination

A

Faces are so important from a
social/evolutionary perspective that they may have a mechanism all to
themselves

73
Q

what is prosopagnosia

A

Impairment of face processing that doesn’t come from damage to early visual processing

74
Q

what is the fusiform brain area

A
  • Part of the ventral (what) stream
  • Responds to faces more than
    other types of objects in
    functional imaging experiments
75
Q

what is evidence for holistic processing in face recognition

A

Sighted people are slower and less accurate at identifying inverted (upside down) faces

76
Q

why does Gauthier suggest that faces are special

A

we have become experts at within-category discriminations

77
Q

what is a criticism of the holistic processing model of facial recognition

A

not all prosopagnosic
patients are impaired on within-
category discrimination

78
Q
A