Lecture 10

Question 1

what is in a face?

Answer 1

Age
Race
Sex
Health status
Internal mental state
Personal identity

Question 2

what is the Pareidolia phenomenon?

Answer 2

· The brain sometimes detects and recognises faces and patterns in collections of objects where there should be none.

· This image was detected automatically in an image from the Lunar Reconnaissance Orbiter by a computer system using face recognition technologies.

· The L+R fusiform gyrus’s ability to detect faces and patterns in organisms and nature leads to a phenomenon called Pareidolia.

Question 3

how does face processing in infants work?

Answer 3

This sensitivity to faces can be traced back to birth, as newborns are able to process faces which was tested through tracking their attention (looking time/behaviour)

Recognising faces develops quite rapidly in infants and then gradually into adolescence

But from 4-6 mths old to 10-12 mths old we lose our ability to distinguish syllables in non-familiar language

6 months old infants can discriminate both human and monkey faces

9 months old infants (and adults) can discriminate human faces but lose the ability to discriminate monkey faces

Question 4

what are features : face perception?

Answer 4

Eyes, mouth, nose etc. Each are identifiable parts that vary in subtle ways across individuals

Question 5

what is configuration : face perception?

Answer 5

the arrangement of face features (spacing, symmetry, position within face outline)

Question 6

what is holistic (configural) face processing?

Answer 6

• Holistic processing:
  Involves integrating information from an entire object
• There is evidence that faces (but not other objects) are recognized through holistic processing

Question 7

what are inversion effects?

Answer 7

faces are hard to process inverted (upside down) than other objects

flipping the face upside down disrupts that crucial configuration

Question 8

what do face inversion effects suggest?

Answer 8

Suggests that as you become an expert at something the more important configural processing becomes

Question 9

what is configural processing; getting a ‘likeness’?

Answer 9

• Configural processing is crucial for getting a ‘likeness’ in a portrait, meaning it is crucial to person recognition.
• Face recognition is difficult when configuration is disrupted.
• Experiments use “composite faces” (separates top and bottom)
• Recognition is dramatically impaired; arguing for importance of configuration processing.
• The details of the features are less important.
• ‘Likeness’ appears to be largely carried by the configuration

Question 10

what is the thatcher illusion?

Answer 10

when local features like the eyes and mouth are flipped on an upright face, but when the whole image is flipped it looks more normal

Question 11

what is the identity after-effect?

Answer 11

• A 50:50 mixture of two people’s faces looks like both of them or neither of them in equal measure.
• We might expect cells sensitive to the two individuals to be equally active.
• Prolonged viewing of one of the two individuals results in cells sensitive to that individual adapting – inhibition over time.
• Subsequent viewing of the 50:50 mix results in it appearing more like the other individual.
• The neural code has been biased in favour of the “less familiar” or previously un-viewed individual.
• Evidence for face-identity cells?
• Or evidence of adaptation to local features?

Question 12

what substructure is most concerned with emotion?

Answer 12

superior temporal sulcus

Question 13

what is the emotion after-effect?

Answer 13

adapting to a happy face makes a neutral one look angry

adapting to an angry face make a neutral one look happier

this suggests our brains are processing emotions as well in a similar way through adaptation

Question 14

what are the two main stages in the bruce and young ‘face model’?

Answer 14

Structural encoding occurs first (deals with viewpoint, lighting and visual analysis of visual object)

Extended processing splits to two separate pathways Expression analysis

Face recognition

1. Coding expression (changeable) and coding identity (fixed) use separate pathways.
2. Familiar and unfamiliar faces are processed differently.

Note: The arrows only go in one direction out of structural encoding. This is an outdated view

Question 15

what is the model of the distributed human neural system for face perception by Haxby, Hoffman, and Gobbini (2000)?

Answer 15

• Forward-backward interaction.
• LTM influences (early) structural encoding stage.
• Emotion expression is more tightly linked to person knowledge (identity) and can also influence structural encoding.

Question 16

what brain imaging techniques are used for face processing?

Answer 16

· ERP’s

· fMRI

· Single cell in monkeys

· Lesion studies in patients

·Brain Stimulation

Question 17

what is an ERP?

Answer 17

ERP: Event related potentials

Question 18

how do ERPs work?

Answer 18

· Put surface electrodes on the scalp; record tiny voltages changes.

· Start voltage measurement when a picture onsets.

· Do this many times.

· Average the signals in a time locked manner.

· The resultant waveform is called an ERP.

Question 19

what is the N170?

Answer 19

A strong negative going signal appears about 170ms post-stimulus when faces are presented as stimuli

This is called the N170 and is an ERP signature for faces.

• N170 is more obvious with face pictures than other objects
• Assumed to reflect structural encoding because it does not generally vary with
  ○ expression
  ○ familiarity
  ○ viewpoint
• But… N170 may be also caused by expertise or simply by highly similar stimuli.

Question 20

what did Bentin and colleagues discover?

Answer 20

Used different stimuli and recorded ERPs. Real faces and cartoon both yield N170.

Shows that brain processes able to extract “faceness” from abstractions of faces.

Question 21

what basic experiment can be conducted concerning fMRIs and face processing?

Answer 21

Present a series of images in different categories
* Face
* Houses
* Chairs, etc.
* Scrambled non-object images
* Subtract activation for ‘scrambled’ from each of the object categories.
Find specific areas of brain that are activated more by one category than other.

Question 22

what mediates brain activity in face-sensitive and house-sensitive perceptual regions?

Answer 22

Attention selection

Question 23

how does modal differ from distributed object category representation in the brain?

Answer 23

Only when you stimulate the rOFA (right Occipital Face Area) do you get a reduction in the performance in the face task

When they inhibited the rOFA, people were less able to make a correct judgement about the faces

But none of their other judgement about the objects or body parts were affected

Question 24

explain the sensitivity of the OFA to face parts

Answer 24

right OFA is critical for part based identification

They found that when you stimulate the right OFA for the performance that is affected is the parts not the spacing/configuration

This suggests the OFA is important for face processing, they were able to identify the specific component or aspect of face processing that the OFA is doing, which is the individual parts themselves rather than the configuration

Question 25

what is repetition suppression?

Answer 25

Brain activity reduced for stimulus repetition. (they get used to it, kind of like brain cell fatigue) The expectation is that the area that cares about that aspect that is repeated will be adopted and therefore will be suppressed Brain areas that show RS are selectively sensitive to the repeated feature. (e.g., Winston et al. (2004). fMRI-adaptation reveals dissociable neural representations of identity and expression in face perception. J Neurophysiol 92:1830–1839.)

Question 26

what is condition 1 of the sample study concerning the rs effect?

Answer 26

Present different images of the same person making different expressions (ID repetition). * If RS occurs, then the brain area is sensitive to face identity and is not sensitive to facial expression. * Finding: RS is found in FFA (fusiform face area) and posterior STS (superior temporal sulcus). * These areas “see” identity; not expression.

Question 27

what is condition 2 of the sample study concerning the rs effect?

Answer 27

Present images of different people making the same expression (expression repetition). * If RS occurs, then the area is sensitive to face expression and not sensitive to face identity. * Finding: RS is found in anterior STS. Codes expression, not identity

Question 28

what conclusion was drawn from this sample study?

Answer 28

face identity and face expression are coded by separate networks in the brain.

Question 29

what is prosopagnosia?

Answer 29

Prosopagnosia is the idea that we can't recognise people based on the face information, even if its people they know really well e.g. mother, father, sister results in a failure to overtly recognise people even if covert measures suggest recognition. ventral route affected may include FFA

Question 30

what is capgras delusion?

Answer 30

results in a feeling that people are imposters even though they are overtly recognised dorsal route affected may include STS

Question 31

what pathway is the STS located in?

Answer 31

Dorsal 'where' / 'Action' motion, 3D shaped, events

Question 32

what pathway is the OFA and FFA located in?

Answer 32

ventral 'what' / 'perception' outline, colour, form

Question 33

how do we process positive expressions?

Answer 33

involves muscles near eyes and mouth a "genuine" smile (b) involves eyes + mouth a polite smile (a) involves only the mouth (social conversation technique)

Question 34

how do we process negative expressions?

Answer 34

focus on the eyes, eyebrows, and mouth Reading a face requires attention to eye muscles, mouth position and their effects on nose, cheeks & chin Eye movements to faces reveal how information is acquired

Question 35

how do autistic children process facial expressions differently?

Answer 35

Autistic children spend more time looking at the mouth than the eyes; typically developing children fixate the eyes more than the mouth. This is apparent at very young ages

Question 36

what other ways do autistic people process faces differently?

Answer 36

reduced performance in differentiating faces based on both sex and individual identity in autism show no evidence for face inversion effect (reduced holistic processing) and reduced brain activation for faces correlation between reduced face processing and higher autistic tendency

Question 37

what are faces spaces and the theory of face recognition?

Answer 37

· Faces have many features (e.g. nose length, eye separation). · Imagine a multidimensional space (MDS) where each important features has its own axis. This is face space. Each face has a unique location within this MDS. · The average face is at the centre. · The brain represents this MDS via a network of specialized neurons. · Individuals are recognized by how a set of features deviates from the centre (Valentine, 2000). The magnitude of these deviations are coded and then used to identify an individual.

Question 38

what are the implications of 'face space' theory?

Answer 38

* Each person has their own “average face” because the MDS for each face category is developed from personal experience. * The average face determines attractiveness: average = “beautiful”. * ‘Who you see is who you like’ * Effects of social media? TV? Your own social group? * A powerful idea that may explain aspects of societal divisions & cohesion. * ‘Average face’ also determines recognition. Recognition is generally better the further a face is from average.

Question 39

what are the face(object) space implications?

Answer 39

Different MDS (multi-dimensional space) “spaces” for different categories of faces (or objects), e.g., races, ages, genders. More experience with diverse faces develops more elaborate MDS. Less experience means simpler MDS. ‘Other Race’ and ‘Other Age’ Effect (ORE, OAE) * Difficulty recognising faces of other races. Note: Between-race differences in faces are smaller than within race differences. * ORE is reduced by experience. * OAE may depend on how intergenerational social groups are. Social media: Using filters to “improve” selfies. * Excessive viewing of social media enhanced faces should change your ‘face space’, making real faces seem further away from the mean. A dangerous game! * Whose definition of attractiveness is making image enhancement algorithms?

Question 40

what is visual speech?

Answer 40

supports understanding of auditory speech through tracking the articulation movement important in noisy environment difficulty in autism (characterised by social/communication differences) visual movement - motion processing speech production - motor processing is motion processing or motor production of speech drive visual speech differences in autism