Semantic Memory Flashcards
How is conceptual knowledge organised and represented in semantic memory
Classical defining feature (collins and quillian 1967)
Feature comparison model (smith, shoben and rips 1974)
Prototype model (rosch 1975)
Concept as defined in classical defining feature theory
Represented in memory and defined by its set of features mental representation of category/class of objects wjhich stored vast amounts of representational information
Describe classical defining feature theory (collins and quillian)
Concept defined by features - features that are integral to making it what it is (can also have additional features that vary)
Features are ‘primitive’ to the concept, of equal importance and all examples are equally representative of that concept
organised into a hierachy of super and subordinate groups
Hierarchical organisation of concepts in classical defining feature theory
Hierarchy of super ordinate and subordinate categories -
Super ordinate - all primitively defining features
Subordinate - the individual, independent examples/cases that can vary
Collins and quillan defining feature theory hierachial structure
Knowledge organised in hierarchy in semantic network
Network has nodes (of concepts) and connections between the nodes which connects concepts and concept properties together in terms of their relation to each other
Make semantic judgments by spreading activation across connections - when reach intersection between concepts must verify the relation- eval path for relevance and decide if satisfies constraints
- links can have different critereonalities dependent on how essential each link is to the meaning of a concept
Ways nodes are connected in network (Collins and quillan defining feature)
‘Is a’ - is a member of… - super and subordinate links
‘F’ - is a feature of…
Define cognitive economy Collins and quillan defining feature
Some general features which may not fully apply to ALL examples of a concept is attached to general categories instead of every individual node - those which deviate have own later nose
Ie birds - ‘can fly’
weak theory of cog economy - everytime learn that x is a bird - do not link to all the properties of a bird - instead, make inference of the links with other features unless directly confronted with the info
What does Collin and quillians hierarchical organisation of defining features predict about retrieval of info
Time it takes To acces the info depends on the distance that is travelled - the length of the connection between the two concepts
if reach an intersection between two notes then triggers the decision to verify the relation
How can you test Collins and quillans prediction
Sentence verification task - give and instance/example and ask if it fits into a category
Ie
Canary is a canary (one level)
Canary is a bird (two level)
Canary is an animal (three level)
collins and quillians 1969/1970)
performance on sentence verfication task predicted by how many ‘isa’ and ‘property’ pathways one needed to traverse to verify a sentence
activation retrieval mechanism that spread across
links within the network, and the more links traversed
the slower the retrieval time
clear typicality effect - faster for spiders are bias (no) than something which has slight overlap ie butterfly bird?
Problems with ‘features’ defining feature theory
Not all features are equal
Some more closely associated to a concept than others
Problem with ‘instances’ in defining feature theory
Some instances/examples are more typical of a concept than others
Smith et al ‘typicality theory’ - quicker to identify robin than ostrich as bird in sentence verification task
Problems with ‘defining features’ in defining feature theory
Hard to identify set of features that defines all examples and excludes non members
Problem with categorical boundaries in defining feature theory
Differences between categories are not always clear cut - some atypical instances mean people can’t agree with others or themselves or tomato as a fruit?
Problem with prediction of defining feature theory - rate of response
Sometimes fail - faster to verify ostrich animal than ostrich bird