Forming Impressions Flashcards

1
Q

Gestalt Principles

A
laws that describe how we organize visual input
-we are born with them or we acquire them rapidly
Figure-Ground
Proximity
Closure
Similarity
Continuity
Common Fate
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2
Q

Figure-Ground

A

determine what aspect of a visual scene is part of the object and which is part of the background
-made more difficult if cues aren’t clear

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3
Q

Proximity

A

Elements that are close together in space tend to belong together

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4
Q

Closure

A

if there are gaps in the contour of the shape, we tend to fill in those gaps and perceive the whole object

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5
Q

Similarity

A

the tendency for us to group together elements that are physically similar

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6
Q

Continuity

A

perceive a simple, continuous form rather than a combination of awkward forms

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7
Q

Common Fate

A

things that change in the same way should be grouped together

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8
Q

Expectations

A

what an individual expects to see influences what they do see

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9
Q

Bottom-Up Processing

A

object recognition is guided by the features that are present in the stimulus
-you recognize what you see by analyzing the individual features and comparing those features to things with similar features that you have in memory

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10
Q

Top Down Processing

A

object recognition is guided by your own beliefs and expectations
-priming examples: reading a word flashed on a screen is primed to expect a word from a certain category

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11
Q

Bi-Directional Activation

A

processing of occurs from both directions (Bottom-Up and Top-Down)

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12
Q

Biederman’s Geon Theory

A

we have 36 geons that are stored in memory

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13
Q

Critique of Geon Theory

A

there are certain stimuli for which it is difficult to determine which geons would be used, yet we have no difficulty
-people with brain damage can recognize some category forms but not others

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14
Q

Template Theory

A

we store templates in memory, so when we come across an object we compare it to all our templates

  • match found: familiar object
  • no match found: new template stored
  • difficult because that requires a lot of templates to be stored
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15
Q

Prototype Theory

A

we store the most typical or ideal example of an object in memory (no exact match necessary)
-can easily recognize object we’ve never seen before

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16
Q

Parallel Processing

A

neural processing of object information is done in parallel - brain systems process different components of the visual signal simultaneously

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17
Q

Perceptual Constancy

A

our ability to perceive an object as unchanging even though the visual image produced by the object is constantly changing

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18
Q

Shape

A

we perceive objects to have a constant shape even though the actual retinal image of the shape can change as your point of view changes or as the object changes position

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19
Q

Location

A

we perceive objects as stationary despite constant movement across or retinas as we move our eyes, head and bodies

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20
Q

Size

A

we tend to see the size of the object around us as unchanging, even though as these objects vary in distance from us, the size of the retinal image that they produce can vary quite a bit

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21
Q

Brightness

A

the brightness of objects around us does not change even though the object may reflect more or less light depending on the ambient lighting conditions

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22
Q

Colour

A

objects have a constant colour, even though the light stimulus that reaches the retina may change with different illuminations

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23
Q

Existing Knowledge

A

top down processing on how we see those objects (we know that most object don’t change)

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24
Q

Cues in Scene

A

picking up cues in the rest of the scene and using those as clues to perceiving constancy in an object

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25
Q

Visual Illusions

A

our brain sometimes makes mistakes

  • what happens when given ambiguous or partial information
  • many of our perceptual constancies can be overcome by simply removing the relevant contextual information
26
Q

Cube Illusion

A

module

27
Q

Muller-Lyer line illusion

A

module distance

28
Q

Ames Room

A

depth and distance

module

29
Q

Ponzo Illusion

A

depth

module

30
Q

Magno and Parvo Cells

A

transduce light stimulus into a neural impulse in the retina

  • first step to object recognition
  • axons exit the eye via optic nerve, travel to LGN and end up in primary visual cortex in the occipital lobe
  • responsive to feature detectors
31
Q

Magno Cells

A

in periphery; changes in brightness, motion and depth

32
Q

Parvo Cells

A

throughout; colour, pattern, form

33
Q

Hodgkin and Huxley (1952)

A

recorded electrical activity in individual neurons of the squid - see how individual neurons respond to specific stimuli

34
Q

Lettrin et al (1959)

A

discovered neuron in optic nerve of a frog that responded only to moving black dots (bug detectors)

35
Q

Hubel and Weisel

A

extending into studies of cells in the visual cortex of cats and monkeys

  • learned what type of cortical cells responded to => micro-electrodes in cortex of a cat to record the electrical activity of individual neurons as the cat was shown different types of visual stimuli
  • one slide that had crack in it projected a line tht cause the cat’s neurons to fire like crazy when moved across visual field
  • neurons must respond to stimuli that are more complex than diffuse flashes of light
  • each neuron is very specific about what will make it fire the most
  • respond maximally to shape, position and movemet
  • defines receptive field of the cell
36
Q

3 Types of Feature Detectors

A

Simple Cells
Complex Cells
Hypercomplex Cells

37
Q

Simple Cells

A

responds maximally to a bar of a certain length and orientation is presented to a particular region of the retina

38
Q

Complex Cells

A

responds maximally to a bar of a certain length and orientation, regardless of where the bar is located in the receptive field

39
Q

Hypercomplex Cells

A

respond maximally to bars of a particular orientation that end at specific point within receptive fields

40
Q

Topographical Orientation

A

neighbouring objects in visual field are processed by neighbouring areas of your brain
-not exact –> largest amount of cortex is devoted to processing from the central part of the visual field
-each region of cortex recieves some input from a small piece of the visual field
-within each region, there are cells that analyze specific features of the scene
-some neurons fire maximally to a line of a certain orientation/length/movement; others to colour; others to a certain direction
-clusters of cells in neighbouring regions are doing the same thing for the neighbouring visual scene
==> parallel processing

41
Q

Visual Association Cortex

A

each receive a different type of information from the primary visual cortex about the visual scene ahead
-segregation into two streams according to type of info

42
Q

Dorsal

A

“where” stream
location of objects
movement within visual scene
primary visual cortex - parietal cortex (spatial information)

43
Q

Ventral

A

“what” stream

-what the object is (form and colour)

44
Q

Primary Visual Cortex Processing

A

specific cells responding to specific features of a small portion of the visual field
-has to be combined to form a meaningful whole

45
Q

Columns in Temporal Cortex

A

vertical columns oriented perpendicularly to surface of cortex

  • neurons in the temporal lobe form columns that respond the categories of shapes
  • very specific stimuli - very complex
  • hands, faces, apples, chairs
  • 5 layers in each column; respond to complex stimuli that come from the same category; each respond to slightly different features
46
Q

Visual Development

A

proceeds quickly, but that doesn’t mean that perception is developed as efficiently as sensation

47
Q

Preferential Looking Method

A

measures what kinds of patterns that infant can perceive by measuring which they look at most

  • patterns over plain stimuli
  • high contrast. sharp boundaries between light and dark regions
  • prefer most complex stimuli
  • preference towards more complex stimuli improves as visual acuity improves
48
Q

Form Perception at 2 weeks

A

single feature

49
Q

Form Perception at 12 weeks

A

whole object

50
Q

Form Perception at 3 months

A

whole form given only parts

51
Q

Form Perception at 4 months

A

some sense of perceptual constancy

52
Q

Ganrund’s Size Constancy Study

A

identical bear at two different distances as familiar

large bear viewed as different

53
Q

Newborn Face Preference

A

seem to prefer faces over most other complex patterns

  • we orient toward other people
  • at two months babies prefer attractive faces over unattractive faces
  • look at mother than other people
  • emotional expressions at 5 months
54
Q

Visual Development (overal)

A

we need innate architecture in place or else no amount of environmental stimulation would improve vision
-we also need early visual experience for brain centres to develop normally

55
Q

Critical Period

A

kittens and early deprivation

56
Q

Dr. Deda Gillespie

A

sensitive development periods in kittens

  • 1 month old kittens kept in dark for 3 - 4 days experience degeneration
  • kittens kept in dark for week or longer suffer severe and permanent visual degeneration
  • are these critical periods true for humans?
57
Q

Cataracts

A

only diffuse lights can reach retinas

  • loss of ability to perceive objects, patterns or details
  • babies born with it have correctional surgeries at different stages = different amount of early visual deprivation
58
Q

Lewis

A

what can babies see when they’re born?
How does vision change with age?
Why does vision get better with age?
-need to understand behaviour to get answers
-preferential looking - various cards with thinner and thiner stripes - what they prefer over grey gives a measure of vision
-visual experience and maturation of eye and brain contribute to this rapid development

59
Q

Damage to Primary Visual Cortex

A

loss of vision in some parts of visual field

  • seen as normal
  • perceive objects in those intact areas of the visual field
  • keyhole
60
Q

Damage to Extrastriate Cortex

A

loss of recognition

  • able to see all objects in the scene
  • difficulty recognizing objects
  • visual agnosia
61
Q

Object Agnosia

A

inability to perceive objects

  • unable to identify different objects by sight (despite ability to see object perfectly, normal visual acuity, ability to name object by touch)
  • man who mistook his wife for a hat - glove scenario
  • shows how crucial object recognition is
  • often, the object that a person can’t recognize is very specific
  • can still read (requires different brain mechanisms)
62
Q

Prosopagnosia

A

inability to recognize faces

  • know that are looking at a face
  • can recognize individual features, cant but them together
  • cannot perceive whose face it is
  • must rely on other cues
  • also have difficulty recognizing other specific stimuli but can recognize categories of objects