M3, face recognition and face processing problems Flashcards
Prosopagnosia
- Not unitary disorder -> a general term describing an inability to recognise familiar faces and the inability to learn new faces (can be acquired or developmental)
- termed coined by Bodamer (1947), possibly first report of distinct face recognition impairment
- Charcot (1883) and Wilbrand (1882) reported patients with face recognition problems but patients also had widespread perceptual problems and memory difficulties
Cognitive evidence for a specialist face processing module (system)
Visual Illusions with Faces
- Face Inversion effect (Yin, 1969)
- Thompson or Thatcher Illusion (Thompson, 1980) (inverted features)
- Composite Face Effect (Young, Hellawell & Hay, 1987)
Face inversion effect
- Face recognition more difficult for inverted compared to upright faces
- Evidence – upright faces = holistic analysis
- Inverted faces = analysis by parts (cannot use face system)
- Evidence consistent with prediction of impaired face recognition only upright faces
- > Normals – correct 94% upright, 82% inverted
- > LH (prosopagnosic patient) – correct 58% upright, 72% inverted
Patient (cognitive) evidence for specialist face processing system
Farah (1990), Acquired alexia
- Reading problems, read letter by letter
- Visual confusions between words e.g., 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)
Neural evidence for specialist face processing system
- Often co-occurrence of object and face recognition impairments
- Impairments face recognition – associated with multiple lesions
- Bilateral lesions – multiple strokes, head trauma, encephalitis, poisoning
Neural evidence for specialist face processing system - single cell recordings in primates
Stimuli presented: monkey faces, human faces, stimuli with face features/characteristics
Found cells that selectively responded to
-> frontal monkey profile
-> others all facial stimuli
But cannot conclude cells purely for face processing
Infant development of facial discernment
Normal infants
- Can recognise differences between face like patterns and patterns with same features but randomly organised as soon as 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 recognise familiar faces
- The rapid development of face recognition suggests that this skill might be modular (Fodor, 1983)
Evidence for genetic basis for prosopagnosia
Developmental prosopagnosia – includes individuals with congenital prosopagnosia and individuals who have sustained brain damage either before birth or in early childhood
Congenital prosopagnosia - impairment in face processing that is present from birth, in absence of brain damage; normal intellect and sensory processes
One idea - Developmental Prosopagnosia is caused by a generalised deficit in configural processing
Evidence suggests that Developmental (Congenital) Prosopagnosia runs in families
Bruce and Young (1986) model of face recognition
- Hierarchical and parallel model of face recognition
- Uses stages of processing
- Allows an understanding of the types of different information used when processing/recognising faces
- look up image
Structural encoding stage - Bruce and Young (1986) model of face recognition
- Form a face percept via parallel extraction of different types of feature based information from faces
- Viewer Centred Descriptions – viewpoint specific face representation of the face
- > Provides information relevant to recognition of facial expression, understanding speech, and processing similarities/differences between unfamiliar people (gender/age etc.) by strategic attending to visual appearance of a face
- Expression Independent Descriptions - encode different view points of the face, including the configural layout of the face and specific features
Bruce and Young 1986 model of face recognition - analysis and processing stages
Expression Analysis – determine facial expression independent of face
Facial Speech Analysis – information from lip and tongue movements of speaker
Directed Visual Processing – attention to face characteristics, learning new faces
Face recognition units - Bruce and Young 1986 model of face recognition
- Input from Expression Independent Descriptions
- FRU contains stored structural (visual) description of familiar faces
- FRU activates when there is a strong match between the face encoded and a stored structural description
- Separate FRU for each face we know
- FRU can also be activated via semantic information in the person identity nodes
- FRU responds to a known face, any given angle, but not to other person specific information (e.g., voice)
Nodes and name - Bruce and Young 1986 model of face recognition
Person Identity Nodes
Post FRU activation, then semantic (bibliographic) information about the person is activated (e.g., occupation, person characteristics etc.).
Name Generation Stage
Activation of the PIN and subsequently semantic information allows you to be able to name the face
Cognitive system - Bruce and Young 1986 model of face recognition
- All other processes that may be involved in or relevant for face recognition
- episodic memories, attention and decisional processes
Prosopagnosia and the Bruce and Young 1986 model of face recognition
Prosopagnosia 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
- > Problem with face recognition units