L17 - Face Perception in the Brain Flashcards
1
Q
Why study faces?
A
- Can tell us age, gender, emotion, and who they are
- Where someone looks, and if they are trustworthy, interested in us
- Most frequent cue we see
2
Q
What was the case study of PS?
A
- Woman came to London and got hit by a bus on the head
- Sustained damage to occiptal and temporal lobes of brain
- Profound inability to recognise faces = prosopagnosia
- Impairment effecting recognition of identity from faces
- But knows who people are from other cues
- Called acquired prosopagnosia, and others are natural/through the lifespan
3
Q
What did Bruce and Young do?
A
- Cognitive model of face processing
- Two distinct pathways for processing for visual identity and facial expression processing
- Structural encoding initially where you extract details from faces and when trying to extract facial identity, you have the proportions for each person
- Identity and expression are diff aspects of processing
- One pathway is fixed, and the other is not
4
Q
What is Prosopagnosia?
A
- Acquired through occipitotemporal cortex damage
- Unable to recognise familiar faces, inc family/self
- No impairments in identity of familiar
- Ability to recognise and name other objects is spared
- Within Bruce & Young model, prosopagnosia deficit located at face recognition unit stage
5
Q
What is the neural basis of face perception?
A
- Dorsal visual stream: concerned with locating objects in space to the ‘where’ pathway: occipital to parietal lobes
- Ventral visual stream: concerned with identifying objects: ‘what’ pathway: occipital to temporal lobes = where face perception occurs
6
Q
What is the Fusiform Face Area (FFA)? (With study)
A
- Area of brain specialised for processing faces
- Put people in scanners and presented them with faces vs other categories of objects to compare brain activity
- Specific brain region called Fusiform Face Area in the Fusiform Gyrus - responds more strongly to faces than other objects
- Even when changing the faces stimuli (mismatched), area responds more preferentially to faces
7
Q
What are the face-sensitive areas in the brain?
A
- Occipital Face Area: specialised for faces and shows physical aspects of stimuli
- FFA: specialised for faces and invariant aspects of faces e.g identity
- Superior temporal Sulcus: responds to face and body and has a dynamic stimuli and changable aspects of aspects e.g expression
8
Q
Describe the Occipital Face Area in more detail
A
- Located in inferior occipital gyrus
- Early stage of face perception
- Sends input to fusiform and superior temporal regions
- Defined by greater response to faces than non-face categories = not anatomically defined but functionally defined, like the other areas
- Responds to upright and inverted faces
- Sensitive to physical changes in stimulus
9
Q
Describe the Fusiform Face Area in more detail
A
- Located in the fusiform gyrus
- Defined by greater response to face vs other non-face categories
- Responds more to upright faces
- Sensitive to changes in identity, relatively insensitive to physical changes
- Acquired prosopagnosia usually due to lesions in or around FFA
10
Q
Study looking at OFA vs FFA
A
- Presented morphs between Mag Thatcher and Marilyn Monroe: people will either see one/other
- Adaptation was then repeated so neurons became fatigued
- Had 3 conditions: identical - where both pics are same, within - changing physical features but keeping identity, between - physical features and identity different
- Greater signal change in OFA when physical properties were changed
- Greater signal change in FFA when perceived identity change
11
Q
Describe the Superior Temporal Sulcus in more detail
A
- Located in superior temporal sulcus
- Responds to faces, but also to other stimuli like bodies, eye gaze
- Changeable aspects of faces (viewpoint, gaze direction, expression), but not identity
- Responds to moving bodies and to changes in gaze direction
12
Q
What was the updated model of face perception?
A
- Distributed neural system for face perception
- Core system: includes Inferior occipital gyrus, lateral fusiform gyrus, superior temporal sulcus
- Core system interacts with extended system: includes amygdala etc.
- Proposed that there are two pathways: facial expression, and identity
13
Q
Is the FFA expertise or specificity? (specific to faces or region that responds preferentially to a category that we are expert at) (what are the arguments)
A
- Domain-general (expertise) vs domain-specific (face specificity)
- Expertise argues that face-specific mechanisms are highly specialised for distinguishing between exemplars of a category
- Face-specificity: argues that face perception is a process occurring in dedicated, specialised cognitive and neural mechanisms: faces are specific discrimination
14
Q
What is evidence for the face specificity hypothesis?
A
- FFA responds more to faces than non-face categories
- Activation to faces is more consistent and much more robust than face-selective activity in OFA and STS
- But this neither conclusively provide evidence that FFA activation to faces supports this because faces are so special and theres nothing similar we are so familiarised to
15
Q
What is the evidence for the expertise account?
A
- Faces require discrimination within a category
- We become experts at face discrimination through prolonged experience
- FFA sensitive to expert within category visual discrimination
