Lecture 21: Vision II- Face perception

Question 1

What is the evidence that face perception constitutes a cognitive module?

Answer 1

1. domain specific: Yes! Double dissociation between face and object processing
2. innate: maybe, infants prefer face-like stimuli, critical period for developing normal face perception
3. informationally encapsulated: Yes! face inversion effect
4. mandatory: Yes! the chimeric face effect; configural processing is mandatory; even though you don’t want to process both faces, you do
5. hardwired in the brain: Yes! fusiform face area

Question 2

Face inversion effect

Answer 2

normal subjects show a much slower RT and lower accuracy for upside-down faces than for other categories (when face is upside down, have to rely on object recognition)

Question 3

Face cells in monkey inferotemporal cortex

Answer 3

neural firing spikes when presented with a picture of a face; firing decreases as face becomes less distinguishable; prefer face stimuli

Question 4

N200 wave for face stimuli in intracranial electrode recording

Answer 4

wave that appears for face stimuli in intracranial electrode recording; face specific component in inferotemporal cortex

Question 5

fusiform face area

Answer 5

this is an area of the brain that shows higher activation to faces than objects; located in the ventral stream on the ventral surface of the temporal lobe on the lateral side of the fusiform gyrus; lateral occipital lobe shows higher activation to objects than faces

Question 6

Prosopagnosia

Answer 6

impairment in recognizing other individuals by their faces; not a basic vision problem; not a problem understanding/remembering identity –> can recognize people based on voice

Patient WJ: suffered from strokes, now has this, can still recognize individual sheep –> impairment selective to human faces

may be able to describe features of face and facial expression but can’t remember names and make connection from photo to person in real life

a single dissociation: “selective” impairment could be due to the fact that faces are very similar, more difficult to tell apart –> harder so it goes first

Question 7

object agnosia

Answer 7

impaired object recognition; can only guess object identity based on context (e.g., pen in marble stand = trophy won for research); difficulty with category of prior expertise (e.g., toys soldiers –> couldn’t tell who’s who)

Question 8

Double dissociation between prosopagnosia and object agnosia

Answer 8

suggests independence of visual systems; A situation in which a single dissociation can be demonstrated in one person, and the opposite type of single dissociation can be demonstrated in another person (i.e., Person 1: function A is present; function B is damaged; Person 2: function A is damaged; function B is present).

Patient CK: head injury at age 27 while jogging, object agnosic, but his face perception is normal (even with complex face-recognition task)

Patients CK and WJ are strong evidence for this

Question 9

Patient CK: upright faces, iverted faces, objects

Answer 9

object agnosic (can’t process objects); performance for inverted faces is very poor, can’t handle the face upside down –> not because is impaired whenever face identification is difficult; he’s fine with identifying disguised famous faces BUT because when face is upside down, have to rely on object recognition

Question 10

Chimeric faces and young, Hellawell and Hay’s study (lab 4)

Answer 10

composites of the top and bottom of two different face; name the top/bottom half of the composite face

Young, Hellawel & Hay: composite (aligned) slower than noncomposite (misaligned) –> composite forms new face; aligned components combine into one face automatically - interfere with part recognition –> this process does not occur for inverted or misaligned components: composite = noncomposite because rely on object recognition now

Question 11

Critical period for face (configural) perception

Answer 11

.