Perception: Agnosia + Prosopagnosia

Question 1

What is agnosia?

Answer 1

failure to recognise objects

• cannot be attributed to loss of knowledge
• supports modularity of the brain

Question 2

Damage to what area of the brain typically results in agnosia?

Answer 2

occipital or inferior temporal cortex

- still have sufficiently preserved visual fields

Question 3

What are the 2 type of Agnosia being covered?

Answer 3

1. Apperceptive Agnosia

2. Associative Agnosia

Question 4

Describe apperceptive agnosia

Answer 4

• able to move about + negotiate obstacles without difficulty
• absence of low-level binding features
• Unable to perform basic copying + matching tasks

Question 5

What are low-level bindings features?

Answer 5

• angles, lines, corners

Question 6

What did Goodale + Milner in 2004 find about appreciative agnosia patients?

Answer 6

revealed they have knowledge of size + shape

Question 7

What are the stages of object recognition?

Answer 7

1. Local features
2. Shape representation
3. Object representation

Question 8

What part of object recognition does appreciative agnosia seem to affect?

Answer 8

Stage 2: Shape representation

Question 9

Describe associative agnosia

Answer 9

• CAN copy + match shapes
• UNABLE to name object despite knowledge
• a failure in accessing knowledge about the object

Question 10

What stage of object recognition does associative agnosia seem to affect?

Answer 10

Object representation

Question 11

What is prosopagnosia?

Answer 11

• loss in ability to recognise faces

- usually due to right inferotemporal lesion

Question 12

Although recognition via visual input is not working, can the person be recognised in other ways?

Answer 12

YES

- voice

Question 13

Although overtly, there may seem to be no recognition, what evidence is there to suggest at some level patient does recognise the person?

Answer 13

1. skin conductance response
   - peak in SCR 1-5 sec after face shown
2. Recognition without feelings: Capgras Delusion

Question 14

What did Tranel et al in 1985 and Ellis et al in 1993 find about face recognition and SCR?

Answer 14

T = peak amplitudes are larger for familiar faces relative to unfamiliar
E = similar patterns found in P patients

Question 15

What is the Capgras Delusion?

Answer 15

Belief someone close to them have been replaced by an imposter

• face is recognised but identity denied
• Alan Davies - wife
• David - mother + father w/ voice

Question 16

What is the difference between prosopagnosia and capgras delusion?

Answer 16

P = loss of overt recognition
C = loss of covert recognition

Question 17

What are the routes in the brain for overt and covert recognition?

Answer 17

Overt = ventral route - goes through amygdala + hypothal
Covert = dorsal route via the superior temporal sulcus + inferior parietal lobe

Question 18

Losses in which streams of the brains result in prosopagnosia and capgras delusion?

Answer 18

P = ventral
C = Dorsal

Question 19

Who is John?

Answer 19

• loss ability to read + see sharp edges
• was able to copy objects but couldn’t recognise it
• he could tell you what it was using facts about what the object should have
• would make u think he can recognise object if left alone with task = normal people wouldn’t see his deficit