object recognition and sound localisation Flashcards

1
Q

What does perceptual organisation mean?

A

the way information is received from our sense

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2
Q

What is the organisation like in retinal images?

A

they are not organised

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3
Q

What is necessary for object recognition?

A

perceptual organisation

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4
Q

What are the 2 aims of perceptual organisation?

A

perceptual segregation
figure background segregation

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5
Q

What does perceptual segregation mean?

A

the ability to distinguish which elements belong together and form separate objects

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6
Q

What does figure-background segregation mean?

A

where the visual system separates an image into figure and background by identifying one object as a figure so rest forms the ground

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7
Q

What type of driven is the bottom-up approach?

A

stimulus driven

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8
Q

What type of driven is a top-down process?

A

cognitive driven

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9
Q

What are the 6 laws of perceptual organisation?

A

law of…
similarity
pragnanz
continuity
closure
proximity
common region

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10
Q

What is law of similarity?

A

similar elements are grouped together perceptually

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11
Q

What is law of pragnanz (or good figure)?

A

group elements so that the resulting shape is the simplest

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12
Q

What is law of continuity?

A

where smooth curves are grouped together

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13
Q

What is law of closure?

A

group elements in a single, recognisable pattern

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14
Q

What is the law of proximity?

A

elements close together to one another grouped together

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15
Q

What is the law of common region?

A

elements within a boundary are grouped together

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16
Q

What is a criticism of the laws of perceptual organisation?

A

it’s provides a description not an explanation!!!
focus is on the cues the brain looks for not how an image is processed

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17
Q

What provides information for perceptual organisation?

A

natural scene statistics

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18
Q

What are physical regularities?

A

physical properties that commonly occur in the environment we live in

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19
Q

Marr’s theory of object recognition (Structuralist)

A

object recognition as a computational problem

20
Q

What are generalised cones?

A

elementary units which objects are decomposed into

21
Q

Biderman’s extended theory from Marr’s

A

the visual system extracts simple, non-accidental features
these features are invariant
used to infer which geons are present in image

22
Q

What is a geon?

A

a simple 2D or 3D geometric shape
used to represent parts of an object

23
Q

What do structuralist theories like Marr’s and Biderman assume?

A

assume viewpoint independence
but recognition also depends on viewpoint

24
Q

What does modularity mean?

A

refers to how damage in a specific area impairs a specific function

25
What does Agnosia mean? (Lissauer, 1890)
not knowing causes problems not recognising object (visual agnosia)
26
What are the 2 types of Agnosia?
apperceptive agnosia associative agnosia
27
What is apperceptive agnosia?
impaired ability to consciously perceive and discriminate stimuli in posterior right hemisphere
28
What is associative agnosia?
preserved ability to perceive stimuli but inability to interpret what was seen e.g couldn't say what an object it but can draw it
29
Gathier and Tarr: recognition
recognition at an individual level is more common for faces than objets more experience with faces than other objects
30
What is prosopagnosia?
when face perception is selectively comprised after brain damage
31
What areas of the brain does face perception activate?
fusiform gyrus
32
What is visual imagery?
seeing with the mind's eye occurs when visual representation is present in STM but stimulus is not viewed
33
The retina is spatiotopic, what does spatiotopic mean?
means the retina corresponds to positions in space
34
The Cochlea is tonotopic, what does tonotopic mean?
means it corresponds to frequencies
35
What does interaural time difference mean (ITD)?
means the difference in the arrival time of a sound to two ears
36
What does interaural level difference mean (ILD)?
means the difference in the intensity of a sound between two ears
37
Why does sound reach 2 ears at different levels?
due to acoustic shadow
38
What are binaural cues?
auditory cues that help humans locate sound using both ears
39
Lord Rayleigh: Duplex theory
states that low frequency sounds (below 800Hz) are localised using ITD whereas high frequency sounds (above 1600Hz) are localised using ILD
40
Are most sounds in the environment low or high frequency?
low frequency so Interaural time difference is dominant cue
41
What is used to localise low frequency sounds?
interaural time difference (ITD)
42
What is used to localise high frequency sounds?
Interaural level difference (ILD)
43
What does cone of confusion refer to?
how all points on a surface provide same binaural cue
44
What are spectral cues?
a physical cue that helps us locate source of sound but depends on frequency of sound
45
What is head-related transfer functions?
a description of how sound waves are modified by the head, ears and other parts of the body as they travel to the ear
46
What are 2 ways you measure sound localisation?
using an anechoic chamber spectral cue manipualtion