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Flashcards in Week 4 Deck (32):
1

Are the same mechanisms used for face
and object perception?

separate


Are the same mechanisms used for face
and object perception?
Support for specialist face processing module
Evolutionary argument

look at faces

facial expression

salient affective information
Empirical evidence for specialised face
processing module

2

Neural mechanisms

Often co-occurrence of object and face recognition
impairments

impairments face recognition – associated with
multiple lesions

Bilateral lesions – multiple strokes, head trauma,
encephalitis, poisoning

3

Single cell recordings - primates

Superior temporal sulc
us cells in monkeys
Stimuli presented were monkey faces, human
faces or stimuli that had characteristics
associated with faces
Found cells that selectively responded to

frontal monkey profile

others all facial stimuli
But cannot conclude cells purely for face
processing

4

Dissociation of object and face recognition

Patients ok object recognition but poor at face
recognition
Explained by different levels of sensitivity of tests
used for object and face recognition

object – between classes
face – within same class

Dissociate Prosopagnosia from other forms of
agnosia
?

5

McNeil & Warrington (1993)

Sheep farmer suffered multiple strokes
Pick famous faces from an array

Chance performance picking famous faces from unfamiliar
faces

Could pick sheep from his own flock compared to
unfamiliar sheep
Test recognition memory for faces and sheep

Human faces performance at chance

Sheep faces good for both hi
s own and unfamiliar sheep

6

Farah et al (1994)

Patient LH

Patient L.H. – diffuse brain damage after accident
Two recognition memory tests

face stimuli

eye glasses
Study phase half stimuli presented
Test phase all stimuli presented
Task – judge stimulus old/new
Correct performance
LH – 64% faces
63% glasses
Controls - 85% faces
69% glasses
Agnosia – 98% faces
chance glasses

7

Face Inversion Effect

Face recognition more difficult for inverted compared
to upright faces
Evidence – upright = holistic analysis
inverted = analysis by parts (cannot use face
system)
Predict impaired face recognition only upright faces

Normals – correct 94% upright, 82% inverted

LH – correct 58% upright, 72% inverted

8

Unique face recognition processing?

Farah (1990)
Acquired alexia
Reading problems, read letter by letter
Visual confusions between words eg. ball doll
Left hemisphere lesion – angular gyrus posterior
region parietal lobe
(Temporal lobe – face processing)
Specific type visual agnosia – patients can
comprehend, speak and write

Deficit – within category (words)
Often occurs with impairments in object recognition
Object recognition – decompose stimuli into parts
Face recognition – overall configuration (holistic

9

Viewer centred description to the expression independent description (similar to object centred description) (bruce&young 86)

Structural encoding of face ( formation of face
percept)

PARALLEL extraction of number types of face
information


10

(facial) Expression Analysis

what expression is a person making
eg. happy, sad

11

facial speach analysis

speaking, movement of mouth and tongue - lip reading

12

Directed Visual Processing

manipulate facial representations

similarities/ differences between unfamiliar people

13

Face Recognition Units

recognise familiar faces

14

Face Recognition Units : Link

structural encoding face appearance to

person identity nodes

15

Person Identity Nodes

stored information – known people

occupation, personal characteristics

16

Face Recognition Units

structural description
known person’s appearance

fire – seen face resembles stored description

17

Recognise familiar people via other
characteristics/ cues

such as voice, laugh

uses other routes to
access person identity nodes

18

Prosopagnosia

inability to recognise familiar
faces

Bodamer (1947)

coined term Prosopagnosia

first report distinct face recognition impairment ?

Not unitary disorder
General term – inability to recognise familiar faces
Various causes
Identification of Different Types of Prosopagnosia
Difficult – deficit rarely occurs in isolation
Types - two distinct groups
Impaired ability to perceive faces

Defect affects Structural Encoding – model
Impaired face recognition

Intact perceptual abilities but
cannot recognise or process
faces satisfactorily

19

Case study:
Prosopagnosia

Charcot (1883) and Wilbrand (1882)

Reported patients with face recognition problems
but patients also had widespread perceptual
problems and memory difficulties
Prosopagnosia patients
Unable to identify familiar faces

wives, family, friends, themselves in mirror
Know looking at face but cannot identify it
Can use other cues to recognise people

gait, clothing, voice, contex

20

Covert face recognition - physiological
Patient LF

Patient LF (Bauer, 1984)
Task to select the correct name from five alternatives
to match a photograph of a familiar face
LF performed at chance
Skin conductance responses (SCRs) were greater
and more frequent to the correct name compared to
distractors
Tranel & Damasio (1985) – patient shown slides of
faces produced
↑SCRs to familiar faces compared
to unfamiliar faces

21

Covert face recognition - behavioural
patient PH

De Haan Patient PH
Performs at chance on a forced choice terms
requiring to choose the familiar face from two items
Face matching task – are 2 simultaneously
presented faces are the same person
Normals are faster to indicate a match for familiar
compared to unfamiliar faces
P. H. also shows that effect

22

covert face recognition - behavioural

Interference experiment – faces are shown with a
printed name
Name is that of the person, a person with a related
occupation, or an entirely unrelated person
Participants indicate if the name is that of a Politician
Normals take longer if t
he name is unrelated to the
face
P. H. also shows this effect

Associative priming experiments
A prime face is presented before a written name
target
Task decide if target is familiar or not
Normals – faster responses when the prime is
associated with a target compared to when there is
no association between the prime and target or the
prime is the face of an unfamiliar person
P. H. shows the same effect
Not all Prosopagnosia patients show convert effects,
some show affects only to a subset of known people

23

Example of Patient with Defective Face
Perception
Unteroffizer S

Bodamer (1947) Unteroffizier S
24yr old non-commissioned officer wounded in
1944
Result of injury could not recognise once familiar
faces
Could still imagine what faces looked like
Faces all the same

flat, white oval plates
with emphatically dark eyes
Could differentiate between faces and most
types of objects
Few errors on animal faces

rabbit – ok

dogs – no
Correct pick out features

nose, mouth, eyes but no s
ense of face individuality
Familiar faces did not provoke feeling familiarity

failed to recognise his mother

Hairstyle able to dete
rmine age, gender of person

Defective interpretation of facial expression

report movements associated
with facial expression but
affective expression had no meaning

in front of mirror with ot
hers – see his own facial
movements but could not recognise himself
Bodamer concluded Uffz S – perceptual disorder
Ok individual face elements
Poor overall unique character
Therefore impaired feature and configuration analysis

24

Example of Patient with Defective Face
Perception - pallis (55)

Pallis (1955) – patient see nose, eyes, mouth but
reported that they did not add up
Therefore deficit in seeing configuration formed by
individual features more severe than Uffz S

25

Metamorphopsia

perceptual distortion

26

Metamorphopsia (more info)

Bodamer (1947) Two patients saw distorted faces
One patient described faces as having

noses turned sideways by several degrees

one eyebrow higher than the other

mouth askew

hair shifted like an ill-fitting cap
Third patient metamorphic but could recognise faces
to some extent

So
either
perceptual distortions not severe enough to
prevent recognition
OR
perceptual impairments of Prosopagnosia not
same as metamorphopsia

27

Impaired Face Memory

Intact face perception
Material specific memory impairment
Mr W Bruyer et al (1983) - 54 yr old Belgian farmer
unable to identify familiar people for 4 years
impairment began whilst in hospital treatment
cardiac problems
CT scan

bilateral lobe lesions
Verbal IQ 90, Performance IQ 95 (normal)
Faces “less beautiful”
Could see faces and face parts but could not
recognise faces
Was able to

distinguish between human faces

copy line drawings of faces

do gender classification

perceive and interpret facial expression

same/different expression matching

match expression to target

judge appropriateness facial expression with
emotional state pictures eg. clown, funeral

match unfamiliar faces

18

discriminate between line drawings where at least
one feature altered

pick target face from array

as with normal performance worse when stimuli
blurred

if face perception problem
then blurring no significant
effect

match ¾ views to full face view of target

match target face neutral expression to those of
same person with variety of facial expressions (hair
occluded)
Mr W adequate facial percept but unable to use
differences between facial percepts to recognise

Familiar Faces tests with hair-styles occluded
(hoods)
10 famous faces, 5 cued named in prior discussion
X Mr W 1 correct

normals 9.7 correct
Video tapes
X Himself, doctor, neuropsychologist, patient friend, 2
unfamiliar people
X Doubtful about familiarity of himself but all other
unfamiliar
Impaired Face Memory
Familiar Faces Without hoods – hair style seen

Recognise himself – long delay

Friends face – familiar

Might know – Neuropsychologist
Task where faces familiar 8/20 correct
X Of those rejected 8 he knew personally
X Did not recognise celebrities as familiar
Impaired Face Memory
20
Mr W
Severely impaired tasks precise identification
(naming)
Some sense familiarity faces well known to him
Problem accessing previously stored face memories
Ok remembering people by spoken name or voice
problem getting from actual face to memory
representation
Defective face recognition units
faces

28

Anomia (person name)

lack of knowledge of peoples names

29

anomia peoples names case study

GBL McKenna & Warrington (1980)
Patient anomic only for people’s names
Could only name 3/20 photos of famous people
correctly
But could accurately describe 18/20 correct who they
were
Correct 16/20 European towns and 12/12 English
towns

30

Genetic basis prosopagnosia

Normal infants can recognize face like patterns a
few hours after birth
Newborn babies can distinguish between their
mother’s face and the faces of other women at 2
days old
Babies a few months old can recognize familiar
faces
The rapid development of face recognition suggests
that this skill might be modular (Fodor, 1983)

31

Developmental Prosopagnosia

Developmental Prosopagnosia
Congenital Prosopagnosia
One idea - developmental Prosopagnosia is caused
by a generalized deficit in configural processing
Evidence suggests that developmental
Prosopagnosia runs in families

32

Face Anosognosia

inability to recognise familiar faces along with the unawareness of this deficit and complete lack of acceptance

Young, De Hann & Newcombe (1990)
Woman suffered a severe right hemisphere stroke

poor at recognizing familiar faces
She was completely unaware of this impairment
Complete lack of acceptance of this impairment
Able to recognise other cognitive limitations
Possibly explained by the automaticity of face
recognition