week 6: pattern recognition

Question 1

what is agnosia

Answer 1

impairment of object recognition ability

Question 2

how does agnosia work

Answer 2

people can recognise its an object but cant verablise it

Question 3

what are intact for agnosia

Answer 3

processes such as colour, shape and motion perception are intact

Question 4

what did agnosia help us understand

Answer 4

recognising a whole object is more than just recognising its parts

Question 5

what are the 2 cortical pathways for vision

Answer 5

ventral pathway
dorsal pathway

Question 6

ventral pathway route

Answer 6

occipital to temporal

Question 7

what does the ventral pathway do

Answer 7

processes info about object appearance and identity

Question 8

what is the ventral pathway important for

Answer 8

object perception

Question 9

what is the dorsal pathway

Answer 9

occipital to parietal

Question 10

what does the dorsal pathway do

Answer 10

processes spatial info about objects

Question 11

what is the dorsal pathway important for

Answer 11

guiding action

Question 12

what is optic ataxia

Answer 12

intact object recognition

Question 13

what do people with optic ataxia do

Answer 13

inability to use visual info to guide action

Question 14

what part of the brain is optic ataxia associated with

Answer 14

associated with lesions in the dorsal pathway (typically in the parietal cortex)

Question 15

what does face perception require

Answer 15

holistic processing

Question 16

what are the gestalt principles

Answer 16

similarity
closure
good continuation
proximity

Question 17

what is template-matching and feature analysis

Answer 17

we tend to recognise different stimuli as the same object irrespective of superficial variations

Question 18

what is feature analysis

Answer 18

a visual pattern is perceived as a combination of elemental features

Question 19

type of model looking at feature analysis

Answer 19

selfridges pandemonium model

Question 20

how do we recognise 3d objects

Answer 20

the same way we do for 2d, an object is first segmented into a set of basic sub-objects and then recognised as a pattern composed eg. broken up into smaller shapes

Question 21

what are the subobjects of an object called

Answer 21

geons

Question 22

what happens if the 3D object is midsegment deletion

Answer 22

takes alot longer to recognise the object

Question 23

in centre surround receptive fields, what happens if the illumination is the centre

Answer 23

its inhibitory

Question 24

what happens if the illumination is of the surround for receptive fields

Answer 24

its excitatory

Question 25

what is the grandma cell hypothesis

Answer 25

a hypothetical neuron which encodes and responds to a highly specific but complex stimulus

Question 26

weaknesses of the grandmother cell hypothesis

Answer 26

the final percept of an object is coded by a single neuron. However, each neuron’s firing is not so reliable. If that neuron is lost, our perception of the corresponding object would be lost

Question 27

what are some other weaknesses of the grandmother cell hypothesis

Answer 27

perception of novel objects cannot be explained well
flexibility of object recognition cannot be explained well

Question 28

what is ensemble coding

Answer 28

object recognition results from the firing of an ensemble of cells
eg. grandma is broken up into parts (hair, nose, glasses, dress)

Question 29

what is really important to recognition

Answer 29

the context

Question 30

what is phonemic restoration effect

Answer 30

a perceptual phenomenon where under certain conditions, sounds actually missing from a speech signal can be restored by the brain and may appear to be heard

Question 31

when does phonemic restoration effect happen

Answer 31

occurs when missing phonemes in an auditory signal are replaced with a noise that would have the physical properties to mask those phonemes