Week 4 Lecture 4 - face recognition Flashcards
What is prosopagnosia?
inability to recognise faces
What are the demands of face recognition?
Generally same as for object recognition
- recognition in context
- object invariance
- specificity
But faces require higher specificity –> in most situations we need to recognise a specific individual face
- within-category discrimination
Ellis, Shepherd and Davies (1975) studied the effectiveness of the Photofit system.
What did they find?
- Results indicated that this was not a very good way of forming representations of the face
- People have difficulty reproducing likenesses of even familiar faces
- Photofit has the inherent belief that we process local features individually
How are faces thought to be represented?
configurally
Faces are thought be be represented configurally.
What can this mean?
- That the spatial relationships between features are as important as features themselves
- That face features interact with one another
- That faces are processed holistically
A study by Tanaka and Farah was based on the premise:
If parts of faces represented separately then memory for these parts presented in isolation should be as good as when presented within a face
What was the method for this study?
- Learned names to go with a face
- Later asked to pick out ‘Larry’ from two alternatives
- Alternatives were either features presented alone or the whole face presented in the learning context
A study by Tanaka and Farah was based on the premise:
If parts of faces represented separately then memory for these parts presented in isolation should be as good as when presented within a face
What did they find?
- Features learned in the context of a normal face were better tested in that context
- Features learned in the context of a scrambled faces were better tested in isolation
- Concluded that the representation of whole faces based, at least in part, on a holistic representation
A study was conducted by Young et al (1987) into upright and inverted faces.
What was the method when faces were presented on upright??
- half faces of celebrities paired to make a new face in either a composite (aligned) condition or non-composite (misaligned) condition
- ppts asked to name top half or bottom half
- RT measured
A study was conducted by Young et al (1987) into upright and inverted faces.
What were the results when faces were presented only upright?
- Significantly slower to name composite than non-composite stimuli
- Perception of a novel facial configuration interfered with the identification of the constituent parts
A study was conducted by Young et al (1987) into upright and inverted faces.
What were the results when faces were presented both upright and inverted?
- Interference from the configurational information only found for upright faces
- no significant difference in reaction times for composite and non-composite images when picture was presented inverted
What can the Thatcher illusion be explained by?
explained by lack of configural processing for inverted faces
What do face representations seem to preserve in terms of surface characterisitcs?
pigmentation
Bruce and Langton looked at the effects of negation on face recognition.
What did they find?
- turning face upside down effects recognition in one way
- making the image negative effects recognition in a second different way
- using both an inverted negative image combines effects and makes recognition even lower
What are 2 possible sources of information that are adversely affected by negation?
- Pigmentation = skin and hair colour &
variations in these - Pattern of shading and shadow which may help specify 3D structure of face
What did a study into recognition of 3D heads find?
When images lacked pigmentation effects of negation were much reduced
