Network Models of Memory

Psy315 - Classes 29 and 30

(This page last updated 30 March 2009.)

Basic Components of Network Models

• Nodes representing individual ideas
  • Each node has an activation.
• Associative links or associations connecting nodes to one another.
• When the activation of a node rises about a threshold:
  • the represented idea becomes active in working memory.
  • activation spreads across links to other nodes.
• Spreading Activation
  • Once one idea is active, spreading activation allows related ideas to be retrieved and become active.

Aspects of Memory that can be Explained by Network Models

• semantic priming
  • Meyer & Schaneveldt (1971)
  • Lexical decision faster if related word was heard recently.
  • Spreading activation reaches word node before word is presented, so less activation is needed to bring it above threshold and trigger response.
• sentence verification
  • Collins & Quillian (1969)
  • Faster to verify "Canary is bird" than "Canary is animal."
  • Assume network is organized hierarchically
  • Response time depends on time necessary to travel from node to node.
• fan effect
  • Anderson (1974)
  • More time needed to verify sentences when its components are also parts of other sentences.
  • When a node has multiple connections, there is less activation to flow out of each connection.

Increasing Representational Power of Memory Networks

• Label links to represent different types of associations
  • Isa ("Is a")
  • Hasa ("Has a")
  • Other types of links make it possible to represent specific episodes or events.
    • Time
    • Location
  • Propositional Networks
    • Proposition: smallest unit of knowledge with a truth value.
    • Node represent entire proposition
      • Anderson represents this node with an oval.
    • Labeled links to other nodes
      • Agent: the one performing the action
      • Object: the thing being acted upon
      • Relation: the relationship between agent and object

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Psych 315H: Cognitive Psychology Kyle Cave Psychology Dept. U. Mass.