1
Q
first steps to object recognition?
A
- ganglion cells in retina
- axons of them exit via optic nerve
- travel to LGN
- end up in primary visual cortex of occipital lobe
- the primary visual cortex has cells called feature detectors
2
Q
what enhances the response of the water jet propulsion system in the squid?
A
large axons
3
Q
bug detectors
A
- neurons in the optics nerve of frogs
- responds only to moving black dots
4
Q
what three stimuli impact visual cortex neuron firing?
A
- location
- orientation
- direction of movement
5
Q
what is the receptive field of a cell
A
the shape, size, position, and movement of the stimuli that a cell maximally fires to
6
Q
simple cell
A
- respond maximally to a bar of a certain orientation in a particular region of the retina
- receptive field is organized in an opponent fashion: sensitive to location of bar within receptive field
- correct orientation = pass through ON region = excitatory response
7
Q
complex cell
A
- respond maximally to bar of a certain orientation
- some respond maximally to a specific direction of movement
- regardless of where the bar is located within the receptive field
- correct orientation + mb direction = excitatory response
8
Q
hypercomplex cells
A
- respond maximally to bars of specific orientation and direction of movement
- movement must end at specific points within the receptive field
- i.e. correct orientation/direction + touches OFF region = weak excitatory response
9
Q
topographic organization
A
- neighbouring objects in visual field are processed by neighbouring areas in visual cortex
- mapping is not exact BC most of the cortex processes info from central part of visual field (wht’s projected on fovea)
- within each region, specific cells for specific features of scene exist
10
Q
benefit of topographic processing
A
speed
11
Q
why doesn’t the brain just rely on hypercomplex cells?
A
optimal function of each cell while consuming least possible amnt of energy
12
Q
visual integration pathway
A
- extrastriate cortex/visual association cortex
- surrounds area V1/primary visual cortex
- has multiple subregions tht receive diff types of info
- splits into dorsal/ventral streams
13
Q
dorsal vs ventral
A
dorsal: where
- location of objects
- sends info to parietal cortex, which processes spatial information
ventral: what
- form and colour
- sends info to temporal cortex
14
Q
how is the temporal cortex organized?
A
- vertical columns perpendicular to cortex surface
- each column has 6 layers
- each column responds to specific categories, each layer responds to diff features within that category
- i.e. one column for apples, but each layer does a diff. colour apple
15
Q
temporal lobe vs primary visual cortex neurons
A
neurons in temporal lobe respond to more complex stimuli than neurons in primary visual cortex
16
Q
is every object encoded by a specific neuron?
A
- no
- individual cells still respond to a range of stimuli
17
Q
what are objects represented by?
A
unique activity patterns across many cells in several different brain areas
18
Q
do infants prefer looking at patterns or plain stimuli?
A
patterns
19
Q
what kinds of patterns do infants prefer looking at
A
- high contrast
- sharp boundaries between light/dark regions
- look longest at the most complex stimuli they are able to perceive
20
Q
what kind of checkerboard would a newborn prefer looking at?
A
- bigger squares
- if squares are too small, the newborn’s poor visual acuity makes the checkerboard look like a grey surface
- grey surface less interesting than a big checkerboard
21
Q
at what age would a newborn prefer to look at a smaller squared checkerboard than a big squared one?
A
two months
22
Q
how do we determine if infants under 2 can perceive whole forms?
A
eye tracking
23
Q
eye tracking
A
used to see where a participant focuses their visual attention
24
Q
at what age to infants begin focusing on whole objects?
A
after 2 months
25
if we show an infant younger than 2 months a shape, where will they look? wht does this prove?
- stare at one corner, not the entire shape
- thus, newborns are naturally attracted to certain key features of a stimulus (angles/edges) not the object as a whole
26
whole form perception is an emerging process over the first __ months of life
two
27
when do infants begin seeing objects guided by gestalt principles?
by 3 months
28
habituation for testing partial/whole form perception in 3 month olds + results
1. present a whole square stimulus until habituated
2. present infant with 4 circle square (4 circles with corner cutouts of square)
- to a 3 month old, the circles are the same as the whole square
- thus, they look at 4 circles outlining a circle for longer
29
which gestalt principle guides 3 month old infants?
- closure
- they can perceive whole objects, not just isolated parts
30
at three months of age, can infants use cues like colour/texture to tell objects apart?
- no
- esp if objects are standing still or moving together
31
in what situation can a 3mo make a distinction btwn 2 diff objects?
if one object is moving independently of the other
32
at wht age can infants use colour/texture cues to distinguish objects even if neither is moving?
5 months
33
when do infants gain perceptual constancy
- 4 months
- gain a handle on brightness, color, and shape constancy
34
at what age do infants gain size constancy?
4-5 months
35
teddy bear in three positions:
- one in front
- same size in back (smaller retinal size)
- larger one in back (same retinal size as first)
where do 4-5mo infants stare longest?
- stared longer at larger bear at back
- treated same size bears at front/back as familiar
- thus, they know objects further away should produce a smaller retinal image naturally
36
benefit of preferring face stimuli over other stimuli for newborns
help build necessary social bond with caregivers
37
at what age do infants prefer looking at attractive faces?
2 months
38
what do two month olds consider to be an attractive face?
- what adults consider to be attractive
- two month olds also prefer looking at their mothers face for longer
39
at what age can infants detect different emotional expressions?
5 months
40
what do some studies also show abt newborns preferring face stimuli? wht does this mean?
- that they have no preference for faces over other complex stimuli
- if there is a face preference, it emerges gradually from early experiences we have with faces
- thus, infants prefer complex stimuli that has a lot of contrast and moving parts
41
1961 study: infants were shown…
- a human face
- complex features of face in non realistic arrangement
- control face without features
- infants preferred looking at 1st and 2nd face to roughly same amount and less at control face
- thus, they preferred complexity of features, not the faces themselves
42
what parts of the face do infants under 2mo look at the most
outer contours (hairline, chin)
43
when do infants begin looking at regions within the face like eyes/mouth?
over 2 months
44
in one study, kittens were raised in a cylinder with just vertical stripes
what happened?
- failed to develop feature detectors for horizontal stripes
- couldn’t see horizontal edges/objects in environment
45
if 1mo kittens are kept in the dark for 3-4 days, wht happens? wht abt for a week+?
- days: visual regions in brain begin to degenerate
- week+: permanent, severe damage to visual regions
46
visual impairment and removal of cataract correlation in infants
the later the cataracts are removed, the greater the visual impairment
47
sleeper effect in cataracts
visual deficits are not revealed until individual is further developed
48
damage to primary visual cortex vs. visual association cortex
primary visual cortex
- looks like keyhole
- can still recognize objects within the reduced boundary of sight
visual association cortex:
- can see all objects in scene
- however, struggle to recognize some/all objects in scene
49
object agnosia
- the inability to perceive objects by sight
- can still see objects perfectly
- have normal visual acuity
- can recognize/name objects by touch
50
Dr P is shown a glove and asked to identify it, wht happens?
- he can state all features of the glove, i.e. 5 pouches/continuous surface
- he can’t put all the info together to determine its a glove
51
can people with object agnosia read?
- yes
- thus, diff brain mechanisms involved in recognizing words than objects
52
prosopagnosia
- the inability to recognize faces (sometimes even their own)
- caused by damage to right fusiform gyrus
- not related to memory dysfunction, loss, or impaired vision
53
what must someone with prosopagnosia rely on to recognize people?
other cues like voice, smell, or a characteristic walk
54
how do people w/ prosopagnosia recognize specific stimuli vs. categories of objects?
- can recognize categories like a dog or car
- can’t recognize their own dog or car
psych 1xx3
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