Psy 102: Sensation

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Psy 102 Sensation Perception
Lecture 8 Shape
Grandmother cells
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4. Face cells
Are there individual cells so highly specialized
that their activity corresponds to recognizing
one individual?
Grandmother cells
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prefer face stimuli
often size and position invariant
Receptive fields cover the entire visual field
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Grandmother coding
Distributed code
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Face adaptation ?
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Face adaptation ?
Can adaptation reveal the dimensions of face
representation?
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Dimensions of face representation Eigenheads
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5. High-level features objects, places, faces,
body parts
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Body Part Area

• Extrastriate cortex in occipital lobe
  extrastriate body area (EBA)
• fMRI shows activity here when viewing whole human
  bodies or parts from photos, stick figures or
  silhouettes but low activity to faces objects or
  animal bodies

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Place recognition

• Inner mid portion of temporal lobe
  parahippocampal place area (PPA)
• fMRI shows activity here when viewing houses,
  outdoor scenes, or buildings

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Object recognition

• Lateral occipital cortex
• fMRI shows activity here when performing object
  recognition tasks
• Damage here leads to object recognition problems
  visual agnosia

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Visual Agnosia

• Patient DF cannot recognize objects or even
  report orientation
• Yet her hands orient correctly to openings or for
  grasping objects
• Supplementary vision in the dorsal where stream

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Visual Agnosia

• Second example of visual agnosia
• Patient can see details but cannot name objects
  or describe their function
• But makes appropriate gestures with his hands

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Face recognition

• Ventral temporal cortex fusiform face area (FFA)
• fMRI shows activity here when performing face
  recognition tasks
• Damage here leads to face recognition problems -
  prosopagnosia

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Prosopagnosia

• Can see details but cant recognize familiar
  faces
• Can tell a face from a nonface
• Emotion recognition can be spared
• Recognize friends from voice, gait, hair style,
  etc.

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Congenital Prosopagnosics
Do not recognize friends, family, self. This
bothers friends a great deal.
I was about 12YO, and I was walking down an aisle
that had columns covered with mirrors (I have a
LOT of trouble with mirrors). I saw a girl
walking toward me, and I thought to myself, "Boy,
is SHE ugly!" You can imagine how depressed I was
when I realized it was me!
Yesterday I went to pick my youngest son up from
daycare. I did not recognize him, and I did not
know who he was. I recognized him by his clothing.
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Prosopagnosia

• Cant recognize own face

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Why a face area?

• Need to recognize individual faces
• Only need to identify the category of objects
• This is a beet or this a lobster
• But not an individual beet or a specific lobster

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Can lose object recognition but spare face
recognition

• agnosia without prosopagnosia
• CK head injury at age 17 while jogging
• normal visual acuity, language, reasoning
• draws well but cant identify later
• cant identify food in cafeteria
• large toy soldier collection as a child

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inverted
disguised
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Video of CK
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Double dissociation
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SUMMARY Neurons specialized for faces Face,
place, object, and body areas Visual
agnosia Prosopagnosia THANK YOU.