1. Verbal Representation of Knowledge
Knowledge: The storage, integration, and organization of information in memory
Information is not equal to knowledge: Knowledge is organized information
Declarative Knowledge: “That”
Procedural Knowledge: “How”

2. Semantic Memory Concepts and Categories
Knowledge without reference to how or where the information was acquired
Encyclopedic information
“Mental Lexicon" ,000 words
Rules

3. Two Types of Concepts
Natural concept
Artifact concept

4. Theories of Semantic Memory Organization
Feature Comparison Model
Prototype/Exemplar Theory
Network Models
PDP/Connectionist Models

5. Feature Comparison Model
Concepts stored in memory in terms of a list of features or attributes
e.g., bird
has feathers
can fly
has a beak
eats seeds
has wings
2 types of features
Defining
Characteristic

6. Sentence Verification Task
"A robin is a bird" vs. "A penguin is a bird“
Results indicate the “Typicality Effect”

7. Pros and Cons Typicality effect can be explained by feature lists
Very few concepts have essential defining features

8. Prototype/Exemplar Theory
Prototypes
Categories are organized around a prototype (Rosch, 1975)
An item is classified into categories by virtue of how similar the item is to a prototype
Prototype of a category does not need to exist

9. Exemplars
Specific examples of a concept learned
New concept compared to other exemplars
Barslou (1992) “bachelor”

10. Problems with Exemplars
Would need to store many exemplars in memory
Evidence still remains that we abstract out information from items coming into memory
Current research: We probably use both

11. Network Models

12. Collins’ Model Collins & Quillian (1969); Collins & Loftus (1975)
Network of nodes tied together by links and associations
2 types of links
Superordinate (SA)
Modifier (M)

14. Spreading Activation
Links frequently traveled have stronger connection strengths

15. Adaptive Control of Thought (ACT, ACT*, HAM)
Anderson (1996, 2000)
Declarative Knowledge
Procedural Knowledge
Working Memory

16. Declarative Network – interconnected set of propositions
Proposition – smallest unit of knowledge that can be judged true or false
Links between propositions can become stronger over time

17. Example: Susan gave a cat to Maria. The cat was white.
Maria is the president of the club.

18. PDP/Connectionist Models
Mental processing units connected together
Parallel operations
Memories stored in connections
Connections modified through connection weights
A memory is not retrieved, it is reconstructed
Default Assignment
Graceful Degradation

21. Advantages May help explain the neural basis for memory
Parallel operations
Explains partial memories