Disorders of perception

Question 1

What information is required for perception?

Answer 1

> Visual sensory information
Deriving a semantic meaning
Naming

Question 2

What visual sensory information is required for perception?

Answer 2

> Colour
Shape
Movement

Question 3

What did Sacks and Wasserman (1987) report?

Answer 3

> (JI)
Visual acuity was good
Achromatopsia (judging colour)
Damage to V4

Question 4

Who linked colour judgement to V4?

Answer 4

Sacks and Wasserman (1987)

Question 5

What did Zihl, von Cramon and Mai (1983) report?

Answer 5

> (LM)
Colour and object recognition fine
Akinetopsia
Damage to V5 / MT

Question 6

What is achromoatopsia?

Answer 6

The inability to judge colour

Question 7

What is akinetopsia?

Answer 7

The inability to judge motion

Question 8

What are the stages of object recognition?

Answer 8

> Visual sensory information
> Grouping - perception
> Feature binding
> View normalisation 
> Structural description system
> Semantic system
> Accessing a name

Question 9

What is apperception?

Answer 9

The inability to create a coherent percept

Question 10

What is association?

Answer 10

Attaching a meaning to a percept

Question 11

Who demonstrated the perceptual effects of apperceptive agnosia?

Answer 11

Warrington and James (1988)

Question 12

What did Warrington and James do?

Answer 12

Demonstrated apperceptive agnosia effects using:
> Object matching
> Copying
> Understanding of overlapping and obscuring
> Unusual views test

Question 13

What are the features of apperceptive agnosia?

Answer 13

> Recognition intact
Unable to copy, match or internally manipulate objects
Inability to form internal percepts

Question 14

What are the features of associative agnosia?

Answer 14

> Visual acuity intact
Can copy, match and internally manipulate objects
Inability to recognise objects or determine purpose

Question 15

What did Rubens and Benson (1971) find?

Answer 15

Individual with associative agnosia, can’t identify objects or determine their function

Question 16

Who demonstrates that associative agnosia impairs the ability to understand or infer an object’s function?

Answer 16

Rubens and Benson (1971)

Question 17

What did Taylor and Warrington (1971) report?

Answer 17

> (FL)
Associative agnosia
Couldn’t match functions to objects
Couldn’t name objects

Question 18

What did Riddoch and Humphreys (1992) demonstrate?

Answer 18

Associative agnosiac can copy images, but can’t commit them to memory or draw from memory

Question 19

Who demonstrated that associative agnosiacs cannot maintain precepts?

Answer 19

Riddoch and Humphreys (1992)

Question 20

Theoretically, where must the visual perception model be damaged to cause apperceptive agnosia?

Answer 20

The grouping stage

Question 21

Theoretically, where must the visual perception model be damaged to cause associative agnosia?

Answer 21

Stored visual representations and meaning

Question 22

What are the limitations of the apperceptive / associative agnosia dichotomy?

Answer 22

> Disagreement about whether shape agnosia is apperceptive
Fractionation
Usefulness of unusual views questioned
Validity of intact percepts in associative

Question 23

What arguments are there that shape processing must be intact in apperceptive agnosia?

Answer 23

> Problems in shape discrimination is a sensory impairment

> Pseudo-agnosia

Question 24

What arguments are there that fractured shape processing can be apperceptive agnosia?

Answer 24

> Shape perception is part of the perceptual process

> Problems with copying or discriminating shapes is a symptom of apperceptive agnosia

Question 25

What evidence is there of fractionation in apperceptive agnosia?

Answer 25

The symptoms of those with apperceptive agnosia are variable

Question 26

What are the criticisms of the unusual views experimental design?

Answer 26

> Most who fail only show impairment in labs
Are problems matching unusual views the same as matching different views?
Suggested location of impairment unlikely

Question 27

What evidence is there that perception may not be intact in associative agnosiacs?

Answer 27

> Type of visual input affects recognition

> Performance on apperceptive tests is good, but method is abnormal

Question 28

What is the object decision task?

Answer 28

> Two objects joined to form a non-object
Presented as either a silhouette or a line drawing
Time taken to determine object as fake recorded

Question 29

What did use of object decision tasks establish?

Answer 29

> Globals forms of stimuli

> Integrative agnosia

Question 30

What is integrative agnosia?

Answer 30

The inability to see objects hollistically

Question 31

Which stages in the stages of recognition model are associated with apperceptive agnosia?

Answer 31

> Grouping - perception
Feature binding
View normalisation

Question 32

Which stages in the stages of recognition model are associated with associative agnosia?

Answer 32

> Structural description system

> Semantic system

Question 33

What evidence is there that there is fractionation in associative agnosia?

Answer 33

> Warrington and Shallice (1984)
Hillis and Caramazza (1991)
Hart, Berndt and Caramazza (1985)
Damasio et al (1996)

Question 34

What did Warrington and Shallice (1984) report?

Answer 34

> (JBR)
Associative agnosia
Ok at identifying living things
Bad at identifying non-living things

Question 35

What did Hillis and Caramazza (1991) report?

Answer 35

> (JJ and PS)
Temporal lobe lesions
Double dissociation between recognition of living and non-living objects

Question 36

What did Hart, Berndt and Caramazza (1985) report?

Answer 36

Category specific associative dissociations

Question 37

What did Damasio et al (1996) repot?

Answer 37

> PET study
agnosiacs and healthy controls
Neural evidence for category specific recognition