Are Faces Special?

Question 1

Are faces special?

Answer 1

Yours is <3

Question 2

What is meant by the term pareidolia?

Answer 2

The phenomenon that we tend to see faces everywhere and in everything

Question 3

In what other way are faces special neurologically (in monkeys)?

Answer 3

There are an abundance of highly tuned cells for them in the InferoTemporal cortex, which is not the case for any other objects really

Question 4

How can these face cells be tuned differently? (3)

Answer 4

Direction of gaze
Emotional expression
Identity

Question 5

Where are these cells tuned to identity located and what are they called?

Answer 5

Face selective cells in the human brain. Cells tuned to specific identity in medial temporal lobe. (e.g Jennifer Aniston cell)

Question 6

How do these face selective cells respond differently than expected

Answer 6

Not strictly visual, also responded to printed name, sound etc

Question 7

What is the name of the brain area found in humans which seemes to be tuned specifically to faces and how was it found

Answer 7

The Fusiform Face Area (FFA) was discovered in the brain using fMRI

Question 8

In which hemisphere is this area more activated to faces?

Answer 8

In the right hemisphere

Question 9

How does this FFA compare to the face selective cells in the InferoTemporal cortex in monkeys? (4)

Answer 9

> Two face areas in each
Human brain the area is more lateralised (more right)
Human responses more invariant (recognise monkey faces too, monkeys not so much for humans)
Monkey region has face selective cells

Question 10

What are the other face areas in humans?

Answer 10

Occipital face area

Superior Temporal Sulcas

Question 11

name another well known category specific brain area

Answer 11

Para-hippocampal Place Area

Question 12

What is the PPA tuned towards

Answer 12

Stimuli with a ‘location’ or ‘place’ element such as landscapes, houses, buildings. Not (so much) to other man-made objects.

Question 13

Is the PPA more prominent in one hemisphere?

Answer 13

Slightly more prominent in the right hemisphere

Question 14

What is special about faces regarding EEG?

Answer 14

There is a special ‘bump’ of activity (Electrophysiological response) associated with them called the N170 response. (This just means a negative potential at 170ms)

Question 15

Describe a study which researched the brain activity surrounding pareidolia

Answer 15

fMRI and MEG study was carried out of the processing of real and illusory faces. They compared these perceived faces with the same objects without these faces and faces themselves. They were asked to say whether they perceived a face or not and their brain activity was also recorded.

Question 16

What were the fMRI results of this study on pareidolia?

Answer 16

The fMRI results showed that the real faces evoked stronger activity than objects in FFA, OFA, LO (lateral occipital cortex) and (even) PPA. Illusory faces are selectively activating FFA and OFA.

Question 17

What were the MEG results of this study on pareidolia?

Answer 17

Real faces are maximally classified from the MEG signals at around 170 ms after stimulus onset, Illusory faces are maximally classified at about the same latency (although a slight delay is visible)

Question 18

What disorder is associated with this perception of faces and what lesions result in it?

Answer 18

Prosopagnosia is a face selective neuropsychological deficit after extensive bilateral or right sided lesions in temporal and occipital lobes

Question 19

How is a ‘double dissociation’ possible with prosopagnosia?

Answer 19

Prosopagnosia patient can recognise objects but not faces.

Integrative agnosia patients recognise faces but cannot recognise objects.

Lesion X= A not b
Lesion Y= b not A

Question 20

What is this double dissociation considered as evidence for?

Answer 20

It is considered the best neuropsychological evidence for a specialised neural module for faces over other objects

Question 21

What criticism is there to the claim that there is a specialised neuro module for faces?

Answer 21

Object recognition is a comparison between categories, face recognition is within category comparison

Question 22

What evidence is there that it is not fair to make a comparison between object and facial recognition?

Answer 22

Face selective neurons first ‘recognise’ the category ‘face’ (at ~60ms), later on (~100ms) recognise different faces or facial expressions

Question 23

How did Martha Farah combat these critiques regarding a specialised neural module for faces? (Describe the study)

Answer 23

She did a study comparing face recognition to within category object recognition in prosopagnosia patients.
She presented subjects with a series of faces/ spectacle frames (that like faces look very similar) and then asked them if they had seen them in an earlier session.

Question 24

What were the results of this faces and spectacles study?

Answer 24

Controls: 87% faces, 63% spectacles
Prosopagnosia patient: 64% faces, 63% spectacles

So also when compared to other ‘within category’ discriminations, faces are special.

Question 25

Name an effect that provide evidence that faces are special

Answer 25

The face inversion effect

Question 26

Describe why the face inversion effect provides evidence that faces are special

Answer 26

Faces are more difficult to recognise when upside down (thatcher illusion- inverting the eyes and mouth is not as easily noticed when it is upside down)

This drop in performance of recognising faces when they are inverted is not replicated when observing other objects.

Question 27

How did Martha Farah test this face inversion effect experimentally and what was the results?

Answer 27

undergraduates and prosopagnosic patients were shown pictures and asked if the next picture in the series was the same or different to the last one you they saw. The next picture was either inverted or not inverted.

undergraduates recognised 94% of the upright photos and 82% of the inverted

Prosopagnosic recognised 58% of the upright and 72% of the inverted

So there is a ‘special’ face module damaged in prosopagnosia. Upside down faces are not analysed in the same way as normal faces. They are now treated as objects.

Question 28

To summarise, name (1) the four arguments that faces are special from the neural perspective and (2) two from the psychological perspective

Answer 28

Neural perspective:
•Face selective neurons
•FFA and other face areas
•N170
•Prosopagnosia vs agnosia

Psychological perspective:
•Pareidolia mostly for faces
•Face inversion effect

Question 29

What is meant by the wholistic analysis of faces?

Answer 29

A face is not so much recognised by its parts. It is recognised by the configuration of the parts, i.e the relation the different parts have to each other (won’t recognise someone based on a nose) (distances between features etc) (mustache effect- still recognising someone when they remove a mustache)

Question 30

How did Martha Farah (again lol) test the parts vs whole hypothesis? What were the results?

Answer 30

She used normal subjects and got them to learn faces and houses. They were tested afterwards to recognise parts of faces or parts of houses. Houses were equally well recognised in both conditions. Faces were better recognised in the ‘whole’ condition.

Question 31

Name an effect that demonstrates how faces are processed wholistically

Answer 31

The composite effect: when the same top half of a face if placed of another face and the two are placed beside each other, it initially appears as tho these two top halves are different. However if bottom half is no longer aligned it becomes immediately obvious.

This effect also appears to disappear when the faces are vertically inverted.> inverted faces are no longer recognised as their wholes but as their parts

Question 32

What alternate non neurological explanations are there for these findings regarding our abilities to process faces?

Answer 32

Faces are everywhere, always. They are used for all sorts of different daily ‘tasks’ so we have automatically become face ‘experts’

Question 33

What neurological evidence is there behind the facial expertise hypothesis?

Answer 33

The FFA is also activated by birds in bird experts, and by cars in car experts. FFA is about ‘visual expertise’ and we are all experts in seeing faces.

Question 34

What criticisms were there of this evidence provided in favour of the visual expertise hypotheses? (2)

Answer 34

McNeil & Warrington (1993) reported a prosopagnosic sheep farmer who could still recognise individual sheep

Assal Faure and Anderes (1984) reported a ‘zooagnosic’ farmer who couldn’t recognise his cows anymore but could recognise people

These findings would be impossible if the damaged areas were general expertise areas

Question 35

Name and describe a condition which demonstrates that facial processing is an instance of dual processing

Answer 35

Capgras delusion: Intact face recognition but thinking that they are imposters

Question 36

What can this illusion apply to

Answer 36

Mostly people e.g family, heighbours or even themselves, thinks that they our imposters, aliens, double etc. however cases have been described where the delusion is that pets or even inanimate objects (such as houses) have been replaced by replicas.

Question 37

How may these symptoms arise?

Answer 37

Can occur in a variety of settings as an idiopathic illness or structural brain damage.

Question 38

Describe Ramachandran’s model of how Capgras occurs

Answer 38

Dual processing: There are two different types of facial recognition. From the analysis of visual from, the FFA, cortex and other areas identify who the person is. The Amygdala and subcortical modules then provides a somatic or emotional response as to who that person is (emotional recognition)

Therefore it is posited that while the physical features are identified through these other areas, the emotional recognition function is inhibited by whatever lesions are caused.

Question 39

What evidence is there for Ramachandran’s model of Capgras? (2)

Answer 39

Capgras patients do not have the increased autonomic response (SCR) to familiar faces that normal people have ( they do have this responses to their voices)

Prosopagnosia patient could not (above chance) name (or select the right name of famous people (or select the right name) of famous people of family members from face pictures. Yet his SCR ‘selected’ the right name above chance (80%/ 62.5%)

Question 40

So how does the flash face distortion effect work?

Answer 40

When you see Bush for a while, neurons encoding bush will adapt (notice how the face also fades for a while). When you then see a Obama, neurons then encode the difference between Bush and other faces will respond more strongly. So you see Obama instead of Bush in the combined image. Vice versa for seeing Obama for a while.

So in the FFDE, the differences between the actors are exaggerated, hence the distortions.

Question 41

What criticism is there to this explanation in regards to the effect of how we perceive faces and the FFDE?

Answer 41

The Flashed Face distortion effect seems not all that face specific, as inversion and manipulating facial features (make-up) have little effect. Basic visual features such as size, duration and eccentricity play a much bigger.

This effect also works for objects. Therefore this flash face distortion effect is more of a general peripheral adaptation effect and not to do with faces at all.

Question 42

Why does this effect work best in the peripheral vision?

Answer 42

It is much more dominated by larger receptive fields, magnocellular input so in the global impression you have of the face the acuity is less specific. Also in the peripheri you have way more transient responses with the magnocellular input so these cells adapt way more quickly than in central vision. This adaptation process is stronger in the peripheri