concepts and knowledge thomas g. bowers, ph.d. penn state harrisburg 2000

Concepts and Knowledge

Thomas G. Bowers, Ph.D.Penn State Harrisburg

2000


We are now moving away from episodic memory to information – Described as semantic memories– Or, sometimes, context-free or

generic memories


What is a dog?– What we know is similar to a

dictionary definition– The definition itself is not completely

adequate


More difficult concepts– What is schizophrenia?– What is truth?– Or virtue?

Wittgenstein (1953) wrote at length on the philosophical nature of these questions


Game is a good example of a concept which does not allow ready definition

Question: How do we decide about a concept?


Use Family Resemblances– “Fuzzy” logic or fit– There may be no definition

• No “necessary” conditions (shared by all)• Or “sufficient” conditions (unique

attributes)


Prototypes are an alternative to definitions– An “average” or representative

member of a class– Marked by fuzzy boundaries – Graded degree of membership

• i.e. a degree of dogginess


How to test the prototype notion?– Sentence verification task– Assesses processing speed for

categorical task– For example, “A chair is furniture” or

“A collie is cat”


Subjects are faster for true sentences

Subjects are faster for familiar categories

Subjects are slower for atypical examples


We can also use a production taskSimply name as many birds as you

can, as quickly as you canLook for convergence with reaction

time tasks


Apple 6.25 Robin 6.89Peach 5.81 Bluebird 6.42Pear 5.25 Seagull 6.26Grape 5.13 Swallow 6.16Strawberry 5.00 Falcon 5.74Lemon 4.86 Mockingbird 5.47Blueberry 4.56 Starling 5.16

Typicality Ratings of Fruit and Bird


Convergent evidence for prototypes– 1. Sentence verification tasks

(McCloskey & Glucksberg, 1979) – 2. Production (Barsalou, 1985)– 3. Picture identification (Smith,

Balzano & Walker, 1978)– 4. Explicit memory of membership

(Rosch, 1975)


Convergent evidence for prototypes– 5. Induction - Inferences from typical

to the whole, but not from atypical to whole

– 6. “Thinking about” categories


Prototypes as heuristics – There may be gains in cognitive

efficiency and economy– Problems can be solved by step by step

algorithm• Tedious, exhaustive, consider and rule out all

choices

– Heuristics - consider only general plan or strategy• Efficient, may overlook possibilities


Schema theory revisited – There is thought to be a network of

associations– Related to each other by propositions– There is a network of relationships


Dog

Cat

Chase

Agent

Object

Action


More complex analysis is possibleSome theories attempt to take into

account complex human relationships

Object Relations Theory

concepts and knowledge thomas g. bowers, ph.d. penn state harrisburg 2000

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