lecture 3- object and face perception

Question 1

Gestalt psychology

Answer 1

Pragnanz, good continuation, closure, proximity, similarity, common fate

Question 2

Contours for visual objects

Answer 2

Some neurons respond at low spatial frequencies- regions and high spatial frequencies- details.

Question 3

Shape from shading

Answer 3

To recognise an object we have to have an idea of it’s 3D shape. Shading is important for this.
When we look at the world we work out from 2d what the 3d shape of the object is using bottom-up processing.

However we have built in expectations and differing experiences- top down processes.

Ambiguous stimuli show that what we expect has a huge influence on what we perceive.

Visual system can influence what is happening in auditory system: BIstable sound demo

Question 4

Challenges to face perception

Answer 4

Discrimination: being able to tell the difference between faces even when similar

Generalisation: once learnt a face, can we recognise across different conditions?

Question 5

Pareidolia

Answer 5

Finding images which do not exist

Question 6

Preferential looking task Goren et al 1975; Johnson et al 1991

Answer 6

Which do infants look at more, face, scrambled or plain.

Preference for face

Evolutionary advantage

Question 7

The face inversion effect Yin 1969

Answer 7

Much harder even though features are the same and arranged the same way- interfering with out ability

Question 8

Negative contrast faces (Kemp et al 1990)

Answer 8

Opposite neurons responding yet we are still able to recognising- we are not only combining features.

Still difficult.

Question 9

McKnone et al 2007 Inversion

Answer 9

Gets worse with dogs but even worse with faces as well as other familiar objects.

However the greatest effect with faces

Question 10

Gauthier et al 1999

Answer 10

Activation of the middle fusiform face area increases with expertise in recognising novel objects

And even more with faces.

Experts in cars, dogs and fingerprints do not get the same size of inversion effects

Question 11

Hollow face illusion

Answer 11

We assume 3D objects are convex.
Hill and Bruce 1994: distance from potato/ face to realise it is hollow.

Upright face- had to get close
Inverted face+ potato- closer

Inverted face is processed as other objects but upright differently

Expectations for faces to be convex overrides our knowledge as well as objects, but stronger for faces

Question 12

Patient CK Moscobich et al 1997

Answer 12

Has damage and struggles recognising objects but not faces.
Has intact vision
This is visual object agnosia

Question 13

Meadows 1974; Damasio et al 1982

Answer 13

Prosopagnosia: struggle to recognise faces but not objects.

Often right anterior inferior occipital lobe lesions in the region of the occipital-temporal junction.

Question 14

fMRI

Answer 14

Kanwisher et al 1997: fusiform face area FFA responds to faces more than other objects.

Question 15

We process hollistically Tanaka and Farah 1993

Answer 15

Shown bobs house door change and nose change

With house, recognise door change.
With face straight away recognise something wrong but not nose specifically.

Question 16

Composite face effect
Young et al 1987

Answer 16

Composite faces interfered with recognition of a half face

The effect disappeared upside sown. Holistic processing obliges us to combine information automatically.

Question 17

Thatcher illusion

Answer 17

Thompson 1980:
Upside down faces we process features separately and do not realise strange relationship between then.

Holistic processing in upright faces makes the unusual arrangement salient.