Object and face perception

Question 1

What is object and face perception

Answer 1

• This is where we look at objects (everything) and change this to meaningful information

Question 2

Detection and recognition

Answer 2

• Our brain forms groups of objects based on sounds
• Our brain can recognise that something is there and then uses our memory to decide what is it
• Colour and orientation and spatial frequency also help with feature detection

Question 3

What is grouping

Answer 3

• Our brain is able to automatically sort features.
  For example, proximity, similarity and closure

Question 4

What happens at a luminance boundary

Answer 4

• Excitation and inhibition cancel each other out when luminance is equal.
• However, at the luminance boundary, there is no balance which means that perceived brightness is increased

Question 5

Contours for visual objects

Answer 5

• Different neurons respond to different frequencies (high and low) for example, Mona-Lisa
• Vital for turning 2D objects into 3D objects

Question 6

Shape from shading

Answer 6

• Shading shows texture and depth which helps to identify 3D objects

Question 7

The role of expectation

Answer 7

• What we expect to see influences what we do see
• ‘built in expectations’
• Everyone has different experiences and expectations

Question 8

Face detection

Answer 8

• First step is to detect a face this means we have to look at different features of the face that are common across all faces
• Template matching is a simple example of detection

Question 9

Face recognition

Answer 9

• After detection of a face, features are analysed to categorise
• For example, different facial expressions help to see the emotion
• Also can identify who it is

Challenges of face recognition:
- There are factors which impact what we see; lighting, different context

Question 10

Are faces special

Answer 10

• Newborns can detect face of their mother
• we have tendencies to see faces in objects
• Pareidolia, we imagine there are faces when there aren’t for example in stones or leaves

Question 11

Evidence for innate ability

Answer 11

• New born studies which look at preferential looking
• New borns look longer at features which are arranges as a face rather than jumbled features.
  Johnsen et al (1991)

Question 12

Face inversion task (Yin, 1969)

Answer 12

• Better at recognising faces the right way up rather than upside down.
• Much more significant for faces than anything else.
  i.e. context is important

Question 13

Negative Contrast faces (Kemp et al, 1990)

Answer 13

• Harder to recognise when pattern of light and dark changes
• Easier to recognise when pattern of colouring is what we are used to seeing.
  i.e. context is important

Question 14

Hollow Face illusion

Answer 14

• Like as mask you would wear
• Painted inside of the mask (indent side) in a way you would paint a face, makes it seem as though the face is popping out at you
• Painting the face to look as though light is hitting it the way you’d expect although works without highlights.
• Blurred lines between perception and cognition as cognitively you know it’s a mask but you can’t override the 3D affect
• Shapes and shading is a bit ambiguous if you don’t know where the light sauce is coming from

Question 15

The affect of inversion on the Hollow Face and the Hollow Potato illusions (Hill and Bruce, 1994)

Answer 15

• Made a potato hollow
• Measure how close people had to get to the object until they see it not as convex (popping out) rather than concave (dimple)
• The closer you are, the illusion went away, potato
• You would have to get closer for the face illusion

Question 16

Do we process faces in a particular way

Answer 16

• The idea that faces are convex overrides knowledge
• Potato illusion shows that we have that same expectation for all objects not just faces
• However, illusion is stronger for faces

Question 17

Face recognition is different to object recognition Moscovitch et al.1997

Answer 17

• Patient CK finds it hard to recognise objects although they do not find it hard to recognise faces

Question 18

Prosopagnosia
Meadows, 1974; Damasio et al. 1982

Answer 18

• inability to recognise certain faces
• Although their object recognise is absolutely fine
• Damage to Temporal areas rather than visual areas.

Question 19

Face specific areas
Perrett et al. (1979, 1982)

Answer 19

• Cells in the superior temporal sulcus are selective for faces. (in monkeys)
• They respond more to human faces than monkey faces

Question 20

Objected Centred vs Viewer Centred
Hasselmo et al (1989)

Answer 20

• Some neurons respond to faces at different angles
• Some respond to animations rather than photos (respond to eye gaze)
• Object vs Viewer, some neurons only recognise from a particular angle but others can respond from any angle
• Not viewer centred, doesn’t matter where we are to the object.
• Memory is important as well as scocial attention

Question 21

Functional Imaging (fMRI)

Answer 21

• Fusiform face area responds more to faces than other common objects
• Haxby et al. 2000, should be looking at other things as well such as eye gaze and different angles may activate FFA differently
• People who can’t recognise faces have damage to the fusiform area

Question 22

Features of Configuration

Answer 22

• There are different features of the face i.e. nose, mouth, eye etc.
• Humans are sensitive to how the face is arranged.

Question 23

Holistic Processing
Tanaka & Farah 1993

Answer 23

Comparison of faces and housing
- trying to recognise a nose and a front door on it’s own is hard
- if you put the front door on the house and the nose on the face it is more recognisable
- Although, still easier to recognise the face rather than the house

Question 24

Composite face effect

Answer 24

• Two faces put together (bottom and top half diff)
• Holistic processing is natural
• Can’t recognise the face when bottom and top half are in one face but when split apart, it’s easier to recognise the face

Question 25

Thatcher Illusion

Answer 25

• When the face is upside down, you can’t notice anything wrong with the image as we interpret each feature of the face separately.
• When the face is then turned the correct way up, we can the odd features (the eyes and mouth are upside down)
• Due to holistic processing when the image is upright we can see what is wrong with it.