Greg Prof. Francis
8/12/11
Faces
Face perception
PSY 200
People are very sensitive to faces
Identity
Health
Dr. Francis
Interpretation of environment
Lecture 11
Why do women wear
cosmetics?
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Faces
Emotions
People see faces where they do not exist
People all around the world tend to interpret some facial
expressions in the same way
Mother
Theresa?
Face-ofgod in
WTC on
9-11?
Martians?
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Detecting emotion
Some of these smiles are real and some are fake
Detecting emotion
Can you tell which is which?
Fake
Real
Real
Real smiles and fake smiles use different muscle
combinations
Real: mouth, raise the checks, eyes crease,
eyebrows slightly dip
Real
Fake: mouth
If intense, eyes crease
Real
Fake
Fake
http://www.bbc.co.uk/science/humanbody/mind/surveys/smiles/index.shtml
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PSY 200: Intro. to Cognitive Psychology
Fake
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Prof. Greg Francis
8/12/11
Facial Features
Facial Features
People focus on some key features of faces
Eyes, mouth
And can fail to notice when things are askew
These images do not look so very different from each other
Another way to describe what happens is that people are unable
to piece together the features and so do not detect the true facial
expression
These images do not look so very different from each other
Margaret Thatcher Illusion
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Facial Adaptation
Further evidence for representations of facial features
come from face adaptation studies
Facial beauty
Average faces are almost always beautiful
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Facial beauty
Average faces are almost always beautiful
Facial beauty
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PSY 200: Intro. to Cognitive Psychology
Average faces are almost always beautiful
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Prof. Greg Francis
8/12/11
Facial beauty
Facial beauty
Average faces are almost always beautiful
http://www.faceresearch.org/demos/average
Averaging is not the only thing that matters
The average of attractive faces is more attractive than the average of unattractive
faces
More sophisticated averaging (morphing) to avoid blurring
Average of four
faces rated as very
attractive
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Cosmetics
Why do people (especially women) wear cosmetics?
Cosmetics
Averageness: smooths the face, which is a characteristic of average faces
Symmetry: blemishes on one side are hidden from other
Average of four faces
rated as very
unattractive
It makes sense for people to interpret faces this way, because it reflects true
differences between male and female faces
More so than men, the eyes and mouth of women tend to be darker than their skin
Youth: coloring and blush
Femininity: female attractiveness is related to femininity, which is related to some simple
variables (Russell, 2009)
These two faces are identical except that the facial skin on the left is
darker than for the face on the right (eyes and mouth are identical)
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Cosmetics
Contrast alone is enough to modify femininity (most neurons in the visual system
are sensitive to contrast)
The two images have the same skin luminance, but the one on the right has darker
mouth and eye regions
Facial agnosia
Some people (maybe 3% of the population) cannot recognize faces or read
emotions from faces
Famous faces test:
Prosopagnosia
http://www.faceblind.org/facetests/index.php
Women wearing cosmetics have greater contrast than women not wearing
cosmetics (Russell, 2009)
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PSY 200: Intro. to Psychology
Many Cognitive people have it all their lives but do not realize it
Cannot recognize themselves in a photograph by face alone
They know there are different faces, but they all look the same
Recognize people by characteristics other than faces
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Prof. Greg Francis
8/12/11
FMRI of faces
With fMRI, we can identify places
in the brain that respond
differently to faces compared to
other stimuli
FMRI control
This image looks like a young
man with a cap in profile
There is a set of images like this
(called Mooney images)
Inverting the image changes
the percept dramatically
What happens in the brain?
fMRI scan while viewing each
type
Subtract responses to find the
difference map
This should be activity that is
present when seeing a face
but not present when not
seeing a face
Activity at other visual areas
should be similar
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fMRI
Face area?
Stronger responses to faces
Fusiform Face Area (FFA)
Region in the fusiform gyrus
Region of the temporal lobe
However, these results do not necessarily mean the FFA is responsible for
detecting faces
Humans are very practiced at detecting faces, maybe the FFA is involved in
practice and expertise
Gauthier et al. (2000)
Participants see a sequence of objects (cars, faces, birds, other), judge similarity across
trials
Especially in right hemisphere
Participants include car and bird experts (everyone is a face expert)
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Face area?
Bird and car experts show extra activity in right hemisphere FFA when
judging faces or judging items in their area of expertise
Note: the left side of the scan image is the right hemisphere
Grandmother cells?
So faces may be special only because we practice a lot
We earlier dismissed the idea that responses from a single cell might
correspond to seeing your grandmother
However, this does not mean that some cells may not be quite specific in
their responses
Some epileptic patients have electrodes implanted in their brains to help
control their seizures
These electrodes can also be used to record responses to different stimuli
Quiroga et al. (2005) made such recordings in the left posterior hippocampus from eight
patients
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PSY 200: Intro. to Cognitive Psychology
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Prof. Greg Francis
8/12/11
Jennifer Aniston Neuron
Some cells respond to very specific sets of stimuli
Pitt-Aniston Neuron
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Halle Berry Neuron
Some cells respond to very specific sets of stimuli
Sydney Opera House Neuron
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But lots of cells respond more generally
Grandmother cells
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PSY 200: Intro. to Cognitive Psychology
Some cells respond to very specific sets of stimuli
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Sydney Opera House & PittAniston Neuron
Some cells respond to very specific sets of stimuli
These results indicate that a neuron may have great selectivity in its
responses
However, the researchers could not test all possible images. Maybe the
Jennifer Aniston cell would also respond to other images that were not
tested
Thus, it may be a mistake to suppose that there is a single cell whose
firing corresponds to thinking about Jennifer Aniston
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Prof. Greg Francis
8/12/11
Conclusions
Face detection
Features and illusions
Next time
Expertise
What does it do?
How could you not see it?
Agnosia
What is attention?
Beauty
Attention
Emotions
Grandmother cells
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PSY 200: Intro. to Cognitive Psychology
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