M5, T1, Semantic memory and category specific details

Question 1

Long term memory system

Answer 1

*look up image

Question 2

Explicit/Declarative memory

Answer 2

Autobiographical Memory
- Personal
- Specific Events

Semantic Memory
- Knowledge about the world
- Fact

Question 3

Why is semantic memory important?

Answer 3

• Names and physical attributes of all objects
• Origin and history of objects
• Names and attributes of actions
• All abstract concepts and their names
• Knowledge of how people behave and why
• Opinions, beliefs, knowledge of historical events
• Knowledge of causes and effects
• Associations between concepts, categories etc.

Question 4

Most everyday cognitive activities rely on semantic memory

Answer 4

• How to recognise and use objects
• Represent concepts in the form of language
• Fluid and flexible knowledge manipulation, association and combination of concepts
• Reasoning, planning the future or remembering the past doesn’t occur without conceptual content

Question 5

Patients show category specific problems - Hillis & Caramazza (1991), Task – name line drawings

Answer 5

JJ - left temporal lobe and basal ganglia damage
- animals 91% correct
- other categories 20% correct

PS – damage left temporal lobe and smaller damaged areas in the right temporal lobe and frontal lobes
- animals 39% correct
- vegies 25% correct
- other categories 95% correct

Question 6

Category specific problems - patient JJ example

Answer 6

Lion: “A large animal, about four feet tall, maybe taller at the shoulders, it has a long body and very large paws and stands on all four legs. It has a monstrous head with which it growls, and it has a mane - a large body of hair. It lives in Africa”

Melon: “I’m not sure, it’s a fruit, a soft material. I don’t remember if it is yellow or green or orange. I’ve forgotten too many things”

Question 7

Category specific problems - patient PS example

Answer 7

Bird: “A fish”

Apricot: “Like a peach, only smaller. You can buy them canned or dried or fresh”

Question 8

Category specific impairment, patient EW

Answer 8

Patient EW had semantic impairment for things from the animal category compared to other categories and her deficit did not extend to other living things
Tested EW on range of tasks:
- Picture Naming Task (look up image)
- Sound Identification Task
- Object Decision Task
- Part Decision Task
- Visual Processing
- Central Attribute Judgement

Question 9

Patient EW, sound identification task

Answer 9

Based on sound characteristics EW impaired animal naming compared to naming non-animals
- Animals 8/32; 25% correct
- Non-Animals 20/32; 63% correct
- Deficits not limited to visually presented information

Question 10

Patient EW, object decision task

Answer 10

EW’s performance significantly below normal range for differentiating real from unreal animals
- EW 36/60; 60% correct, Control mean: 54/60; 90% correct

EW’s performance within the normal range for differentiating real from unreal non-animals
- EW 55/60; 92% correct, Control mean: 50.5/60; 84% correct

Question 11

Patient EW parts decision task

Answer 11

EW impaired on this task for animals
60% correct; Control mean 100%

EW Ok when stimuli were artifacts
97% correct; Control mean 97%

Question 12

Patient EW central attribute judgement task

Answer 12

*look up central attribute questions
*look up patient EW central attribute task

EW attributes relating to animals, 65% correct, Controls range 85-100% correct

EW performance within normal range for attributes relevant to non-animals, 95% correct, Controls range 86-100% correct

Question 13

Methodological considerations for category specific impairments

Answer 13

Is there such a thing as a category specific deficit, or is this due to task differences?

Task differences could be the result of…
- Familiarity (how familiar people are with a word/object)
- Frequency (how often the word/object appears in usage)
- Visual complexity
- Processing Difficulty Hypothesis

Question 14

Funnel and Sheridan (1992) patient SL (frequency consideration)

Answer 14

• Reported to have category specific deficit for living things
• When matched items on familiarity (frequency) no deficit

Question 15

Stewart et al., 1992 methodological considerations

Answer 15

Patient HO
- Reported to have category specific deficit for living things
- Shown items and asked to name them – he was much worse for living than non living things
- BUT when items were matched on familiarity, word frequency and visual complexity of the picture, there were no longer these category specific effects

Question 16

Task differences and specific category impairments

Answer 16

Capitani, Laiacona, Barbatotto, and Trivelli (1994)
- Non brain damaged participants find it harder to answer questions about living vs. non-living things, even when items are matched

Gaffan and Haywood (1993)
- non brain damaged participants find it harder to visually discriminate living versus non living objects