Perception Flashcards

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1
Q

Where is the retina located?

A
  • We have the cornea and the pupil in the front
  • And in the back we have the Retina, and in the retina we have 2 types of receptors
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2
Q

What are the two receptors in the retina?

A

Rods
Cones

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3
Q

What are the properties of Rods?

A
  • Sensitive to light and movement
  • 125 million in the retina
  • Magnocellular Pathway = sensitive to motion, most input from rods
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4
Q

What are the properties of cones?

A
  • colour vision, sharpness of vision
  • 6 million in the outer regions of the retina
  • Parvocellular Pathway = sensitive to fine detail, most input comes from cones
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5
Q

What is the pathway from eye to brain step by step?

A
  1. Retina
  2. Optic nerve
  3. Optic chiasm
  4. Lateral Geniculate Nucleus
  5. Cortical area V1
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6
Q

What are the 3 properties of visual neurons?

A

Receptive fields
Retinopy
Lateral inhibition

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7
Q

What are receptive fields?

A

every neuron is responsible for a certain region of space
- And it will fire more when when something happens in that space and won’t fire when something happens in another space

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8
Q

What retinopy?

A

The neurons that are near to each other in space are processed in cells that are physically near to each other

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9
Q

What is Lateral inhibition?

A

one neuron can inhibit a neighbouring neuron (useful for enhancing contrast at edges of objects)

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10
Q

What is the first stop in the brain before going to the cortex?

A

Lateral Geniculate nucleus
- Part of the thalamus
- Cells have a centre- surround receptive field
- Maintains a retinotopic map

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11
Q

What is the stop after the lateral geniculate nucleus?

A

Primary visual cortex (V1)
- Extracts basic information from visual scene
- Sends this info for later stages of processing.
- Maintains retinotopy

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12
Q

What does functional specialisation theory propose?

A

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

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13
Q

What is the function of V1 and V2 according to functional specialisation theory?

A

Early stage of visual perception

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14
Q

What is the function of V3 and V3a according to functional specialisation theory?

A

Responsive to form

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15
Q

What is the function of V4 according to functional specialisation theory?

A

responsive to colour

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16
Q

What is the function of V5/MT according to functional specialisation theory?

A

responsive to visual motion

17
Q

What does damage to V1 cause?

A
  • leads to clinical diagnosis of cortical blindness
  • The patient cannot consciously report objects presented in this region of space
  • However they can still make some visual destinations in the “blind” area e.g. orientation of the movement of the object
18
Q

What does damage to V4 cause?

A

Patients with cortical Achromatopsia
- cant see colours due to damage to V4 but also often due to damage to V2 and V3

19
Q

What does damage to V5/MT cause?

A
  • leads to Akinetopsia
    Motion perception becomes deficient
20
Q

What are the two pathways beyond the visual cortex?

A
  • Parietal/ dorsal processing pathway
  • Temporal/ ventral processing pathway
21
Q

What is the parietal/ dorsal processing pathway?

A

the where pathway
Concerned with movement processing

22
Q

What is temporal/ ventral processing pathway?

A

the what pathway)
Concerned with colour and form processing

23
Q

What is gestalts law of organisation

A

explain how humans perceive stimuli and create shortcuts in our brains to make sense of incomplete pictures.

  • Proximity
  • Similarity
  • continuation
  • closure
24
Q

State the 4 step model of object recognition

A
  1. Early visual processing
  2. Perceptual segregation (grouping visual elements)
  3. matching between grouped visual description with a representation of a object stored in the brain
  4. Attach meaning to the object (such a chair = what you sit on)
25
Q

What is known to be the cause of an object recognition deficit

A

Agnosia = Impairment in object recognition is caused by damage to this pathway

26
Q

What are the two types of Agnosia?

A

Apperceptive agnosia

Associative agnosia

27
Q

What is apperceptive agnosia?

A
  • Impairment in the process which constructs perceptual representation from vision
  • Results in seeing parts but not the whole
28
Q

What is associative agnosia

A
  • Impairment in the process which attaches meaning to the object
  • Seeing the whole but not its meaning