Week 4 Flashcards
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
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
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
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
?
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
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
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
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
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
(facial) Expression Analysis
what expression is a person making
eg. happy, sad
facial speach analysis
speaking, movement of mouth and tongue - lip reading
Directed Visual Processing
manipulate facial representations
similarities/ differences between unfamiliar people
Face Recognition Units
recognise familiar faces
Face Recognition Units : Link
structural encoding face appearance to
person identity nodes
Person Identity Nodes
stored information – known people
occupation, personal characteristics
Face Recognition Units
structural description
known person’s appearance
fire – seen face resembles stored description
Recognise familiar people via other
characteristics/ cues
such as voice, laugh
uses other routes to
access person identity nodes
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
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
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
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
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
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
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
Metamorphopsia
perceptual distortion
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
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
Anomia (person name)
lack of knowledge of peoples names
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
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)
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
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
