Knowledge Representation and Retrieval

1. Knowledge Representation and Retrieval PSY 421 – Fall, 2004

2. Overview • How is information organized in memory? • Retrieving information – propositional networks • Retrieving everyday information • Tip of the Tongue Phenomenon

3. What we have discussed about memory… • Structure of Memory • SM -> STM -> LTM • Working Memory • No distinctions • Memory Processes • Encoding • Retrieval • Match between encoding and retrieval • Forgetting • Evidence for memory distortions • Knowledge Representation in Memory • How can I get the once bit of information out of memory that I need?

4. How is information represented in memory? • Episodic vs. semantic memory • Who taught you how to draw a map? • Who taught you how to use the internet? • Who taught you how to tie your shoes? • Who taught you the words to “Take me out to the ballgame”? • When did you learn how to divide using fractions? • Models of representing and retrieving categorical knowledge • Hierarchical Network Model • Feature Comparison Model • Spreading Activation Model

5. Common Aspects of these Models • Category verification task • Feature verification task • Metaphors for how information is represented • Spreading activation – activation of one node spreads to other related nodes • Primary measure of performance is speed, not accuracy

6. Network Models • Associative network with concepts represented as nodes • Nodes can be “close by” • Try NOT to think of this as a neural model where the nodes are neurons

7. Hierarchical Network Model • Collins and Quillian (1969; 1970) • Specific nodes are nested deeper within the model • Concept nodes and feature nodes • Higher in the hierarchy, the faster you are to access that information • Problems with the model are numerous

8. Feature Comparison Model • Smith, Shoben, and Rips (1974) • Knowledge consists of a set of descriptions of features • Defining features = those that are essential for the meaning of the concept • Characteristic features = those that are not essential; perhaps accidental • Problems

9. Spreading Activation Model • Collins and Loftus (1975) • Concept nodes are organized in an associative network • Associations are not hierarchical • Activations vary on strength • Evidence • Semantic priming

10. Propositional Networks • Proposition = smallest unit of knowledge that can stand alone and be declared true or false • Abstract representations underlying what we think and say (McNamara, 1994) • Networks are constructed from facts and relationships we learn and experience • Foundation for the study of language

11. Evidence for Propositional Networks • Mediated priming = amount of priming of one node to another depends on degree of separation within the network (measure = speed) • Fan Effect = as more and more facts are learned about a concept, the ability to quickly and easily retrieve any one of the facts decreases (response competition/ interference)

12. Everyday Knowledge • Foreign Language Knowledge – long term retention is dependent on initial learning • Permastore – permanent memory for information that is overlearned • Math – if math is learned over a long period of time (many years in school) it is retained longer than if learned quickly • Cognitive Psychology – some forgetting but some facts remembered long term (Research Methods, however, was retained for a long time) • Applications for Education

13. More everyday knowledge • People’s Names • Interaction of face recognition, biographical information, and names • Songs • Repetition within the song • Sharing words with the title • Occurrence early in the song • Association with melody is important

14. Tip of the Tongue Phenomenon • We know we know some piece of information but when asked, we cannot come up with it • Available but not accessible • How often – a few times a week? • Alternatives are not random • More alternatives will actually interference with retrieving the right one (especially phonologically similar alternatives) • Feeling of Knowing

15. Song Lyrics • Somewhere over the rainbow • Somewhere over the rainbowWay up high,There's a land that I heard ofOnce in a lullaby.Somewhere over the rainbowSkies are blue,And the dreams that you dare to dreamReally do come true. • Someday I'll wish upon a starAnd wake up where the clouds are farBehind me.Where troubles melt like lemon dropsAway above the chimney topsThat's where you'll find me • Somewhere over the rainbowBluebirds fly.Birds fly over the rainbow.Why then, oh why can't I? • If happy little bluebirds flyBeyond the rainbowWhy, oh why can't I? • WHAT A WONDERFUL WORLD • I see trees of green, red roses too I see them bloom for me and you And I think to myself, what a wonderful world I see skies of blue and clouds of white The bright blessed day, the dark sacred night And I think to myself, what a wonderful world The colours of the rainbow, so pretty in the sky Are also on the faces of people going by I see friends shakin' hands, sayin' "How do you do?" They're really saying "I love you" I hear babies cryin', I watch them grow They'll learn much more than I'll ever know And I think to myself, what a wonderful world Yes, I think to myself, what a wonderful world Oh yeah