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