Knowledge Organization

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Knowledge Organization

• Simple Concepts
• Complex networks, schemas

Text Eysenck Keane, Cognitive Psychology,
Chapter 9, Concepts and Categories, pp.
293-313 NOT SOLSO!
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Categorization

• How are categories represented?
• Category, class a set of objects
• Concept an internal representation of a category
  (about a category)
• Mechanisms of categorization
• Semantic classification
• Semantic memory (LTM)
• Lexicon (meaning of words)
• Ambiguity (case)
• Polysemy (bird)

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• Bruner, Goodnow, Austin (1956)
• to categorize is to render discriminably
  different things equivalent, to group objects and
  events and people around us into classes, and to
  respond to them in terms of their class
  membership rather than their uniqueness.

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Why categorize?

• Cognitive economy
• Generalization
• Representing important information (loss of
  details)
• Decreasing redundancy
• Prediction

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Research Methods

• Most research NOT about behavior but judgements
  about membership
• Sorting tasks groups reflect underlying concepts
• Property listing task
• Frequency of mentioning centrality of the
  property to a concept

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How are categories represented?

• Definitions?
• Classical view defining attribute approach
• Typical instances?
• Prototype view
• Exemplars?
• Exemplar view
• Theories?
• Theory theory
• Essences?
• Psychological essentialism
• Perceptual and action schemata?
• Situated simulation theory

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Classical view

• Concept a set of defining features
• Each is necessary, and jointly are sufficient for
  classifying an object to a category
• Example bachelor male, single, adult
• World is divided into distinct classes
• Boundaries between them are clear, sharp
• All members are equally good
• Concepts are static, context-independent
• Concepts form hierarchies
• Subordinate concepts inherit features from
  superordinate concepts

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Collins and Quillian 1969
Is a canary a bird lt Is a canary an animalDoes a
canary fly lt Does a canary breatheBut why Is
canary a bird ltlt is ostrich a bird?
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• Problems with the classical view
• Concepts have internal structure of typicality
• Typicality rating order of mentioning (high
  level of agreement among people)
• Faster category membership verification for
  typical exemplars
• Even clearly defined categories exhibit
  typicality structure
• Most concepts are not clear-cut but fuzzy
• Is stroke a disease? Is tomato a fruit or a
  vegetable?
• Difficult to find defining attributes (game)

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Prototype approach (Eleanor Rosch)

• Categories are represented as prototypes
• No defining attributes, only characteristic ones
• Family resemblance
• Fuzzy boundaries
• Membership similarity to the prototype
• Problems
• Some concepts do not seem to have prototypes
• Some features are more important than others
  (diagnostic) it is context-dependent
• Knowledge about feature variability and relation
  between features (not just association)
• Complex concepts (red car pet fish)
• Similarity as a criterion? Ad hoc categories.

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Exemplar approach (Nosofsky)

• Categories collections of instances
• Concepts particular exemplar that comes to mind
  in a given context
• Problem cognitive economy (generalization)
• Both prototype (abstract) and concrete (exemplar)
  processing?
• Laeng et al. 2003 faster verification to
  subordinate category when pictures presented to
  the right hemisphere to basic level left
  hemisphere

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Theory-based categorization

• Categorization depends on deeper knowledge about
  relationships among features (not superficial
  similarity)
• Palmeri Blalock (2000)
• Classification of childrens drawings
• Keil (1989). Children after age 7 theories
• Discovery procedure
• Transformation procedure

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Situated simulation theory

• Barsalou (2003) conceptual system is not a
  detached database
• Flexible (ad hoc categories)
• Context dependent (description typicality
  changes)
• (Perception and action) and conception are based
  on the same representations
• Modal visual properties representations from
  visual system, actions motor representations
• E.g. fMRI when classifying manipulable objects
  motor areas of the brain were active
• Lakoff Johnson, 1999 even abstract concepts
  are embodied in physical primitives (to be in
  love)

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Is all categorization the same?

• Classical scientific, definitions
• Prototype perceptual, rapid identification
• Theory based reasoning, prediction
• Note most theories are about objects, not
  relations (e.g., above, kick)
• Attribute lists for relations?
• Semantic primitives?
• Same problems as with classical view of concepts
• Larger structures (schemata)

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Complex knowledge organization

• Schemata (schemas) A structured cluster of
  concepts
• Relations variables (often with default values)
• Propositions John hit Mark
• Predicates hit (John, Mark)
• Types of schemata
• Scripts (schemata for events), Schank Abelson
• Organized sequences of stereotypical actions
  (e.g. eating in restaurants) action
  variables
• Frames (static e.g. building)
• Spending more time looking at unexpected objects
  changes or absence of expected ones went unnoticed

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• Connectionist models
• Schemas emerge when needed from local
  interdependencies (Rumelhart 1986)
• Critique too unconstrained, vague
• average schemata in a population?
• Acquisition data
• Important e.g., for eyewitness testimony
• Predicting distortion of information

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Bartletts research on recall
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• The War of the Ghosts
• One night two young men from Egulac went down to
  the river to hunt seals, and while they were
  there it became foggy and calm. Then they heard
  war-cries, and they thought "Maybe this is a
  war-party". They escaped to the shore, and hid
  behind a log. Now canoes came up, and they heard
  the noise of paddles, and saw one canoe coming up
  to them. There were five men m the canoe, and
  they said
• "What do you think? We wish to take you along. We
  are going up the river to make war on the
  people".
• One of the young men said "I have no arrows".
• "Arrows are in the canoe", they said.
• "I will not go along. I might be killed. My
  relatives do not know where I have gone. But
  you", he said, turning to the other, "may go with
  them."
• So one of the young men went, but the other
  returned home.
• And the warriors went on up the river to a town
  on the other side of Kalama. The people came down
  to the water, and they began to fight, and many
  were killed. But presently the young man heard
  one of the warriors say "Quick, let us go
  homethat Indian has been hit". Now he thought
  "Oh, they are ghosts". He did not feel sick, but
  they said he had been shot.
• So the canoes went back to Egulac, and the young
  man went ashore to his house, and made a fire.
  And he told everybody and said " Behold I
  accompanied the ghosts, and we went to fight.
  Many of our fellows were killed, and many of
  those who attacked us were killed. They said I
  was hit, and I did not feel sick".
• He told it all, and then he became quiet. When
  the sun rose he fell down. Something black came
  out of his mouth. His face became contorted. The
  people jumped up and cried. He was dead.

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• The War of this Ghosts
• Two Indians were out fishing for seals in the Bay
  of Manpapan, when along came five other Indians
  in a war-canoe. They were going fighting.
• "Come with us," said the five to the two, "and
  fight."
• "I cannot come," was the answer of the one, "for
  I have an old mother at home who is dependent
  upon me." The other also said he could not come,
  because he had no arms. "That is no difficulty"
  the others replied, "for we have plenty in the
  canoe with us" so he got into the canoe and went
  with them.
• In a fight soon afterwards this Indian received a
  mortal wound. Finding that his hour was come, he
  cried out that he was about to die. "Nonsense,"
  said one of the others, "you will not die." But
  he did.

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• Level of narration
• Structure of autobiographical memory
• Predicting feelings and/or behavior on the basis
  of roles played in a story