Concept formation
Categories and concepts
PCategory: set of entities (things, actions,
properties, ...) In the world
PConcept: our mental representation of a category
PAre categories arbitrary? Or based on what is in
the world?
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Concept Formation - Lecture Notes | PSYCH 100, Study notes of Psychology
Material Type: Notes; Class: Introductory Psychology; Subject: Psychology; University: University of Massachusetts - Amherst; Term: Unknown 1989;
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Concept formation
Categories and concepts
P Category: set of entities (things, actions,
properties, ...) In the world
P Concept: our mental representation of a category
P Are categories arbitrary? Or based on what is in
the world?
Borge’s Taxonomy of Fauna
Taken from Lakoff, Women, Fire, and Dangerous Things
The taxonomy of the animal kingdom, from The Celestial Emporium of Benevolent Knowledge : On those remote pages, it is written that animals are divided into (a) those that belong to the Emperor, (b) embalmed ones, (c) those that are trained, (d) suckling pigs, (e) mermaids, (f) fabulous ones, (g) stray dogs, (h) those that are included in this classification, (i) those that tremble as if they were mad, (j) innumerable ones, (k) those drawn with a very fine camel’s hair brush, (l) others, (m) those that have just broken a flower vase, (n) those that resemble flies from a distance. (J. L. Borges, 1966, Other Inquisitions
What are the functions of concepts?
P Permit inferences
< Allow reasoning about new things
P Support communication
< Add new information about concepts < Permit economy of communication
Eleanor Rosch’s position
The “Roschian revolution”
P Observation 0 (Wittgenstein): you usually can’t
find defining features for categories
P Observation 1: an entity usually belongs to several
different categories
< But one is “BASIC”
P Observation 2: categories have better and worse
members
< Categories don’t have fixed boundaries
Basic Level Terms
And superordinate and subordinate terms
P Taxonomies of categories
< Animal-mammal-dog-collie < Artifact-furniture-chair-easychair
P Rosch’s observations
< Basic level the preferred name < Fastest to verify name-object match < Learned first < Shortest < ASL, single sign
Figure 8.10 (p. 279) Levels of categories for furniture and vehicles. Rosch provided evidence for the idea that the basic level is “psychologically privileged.”
Basic level principles
P Basic level: the highest (most inclusive) level at
which all instances share a large number of
features
P Feature listing
< Superordinate (furniture): few features < Basic level (chair): many features < Subordinate (easy chair): only a few more features
P Hemenway, members of basic level categories
have parts in common; not so for superordinates
Typicality and category membership
Within-category structure
P Relations between categories: Basic level
analysis
P Within-category relations: Typicality and graded
category membership
Rate the typicality....
P Fruits
< Apple
< Fig
< Olive
< Grape
P Birds
< Robin
< Bat
< Flamingo
< Seagull
Typicality effects
P Time to identify name as category member
P Time to identify picture as category member
P Ease of learning category membership
P Name members of category: frequency of naming
P Similarity ratings (asymmetry): less typical
members are more similar to more typical
members than v.v.
Prototype models
Alternative ideas of prototype
PIdealized, abstract form
PSome kinds of instances
PMental representation of ideal form or instances
Thought transmission?
P I’ll pick number between 10 and 50
P it has to be odd
P each of its digits has to be odd
P its two digits have to be different
< 11 is not good < 15 is OK
P I’ll write it down and think about it
P Then YOU write down what I’m thinking
Exemplar theories of concepts
These theories contrast with prototype theories
P Prototype theory claim: You lean some kind of
abstraction, some single mental representation of
a category
P Exemplar theory claim: You remember individual
instances (exemplars) of concepts, and compare
new things to these remembered instances to
categorize these new things
Exemplar theories of concepts
Their virtues
PExplain typicality effects very well
PPermit mathematical models
< Supports quantitative predictions of choice, learning
PAccounts for feature variation effects
< “pizza” vs “quarter”
PAccounts for feature covariation effects
< “little singing birds” vs “big nonsinging birds”
Strengths and weaknesses of exemplar models P Strengths < Accounts for typicality effects PLUS variability and covariability effects < Permits development of explicit, accurate mathematical models P Weaknesses < Supporting data come from odd experiments that encourage instance memory < People CAN form abstractions < Model doesn’t address main points of why we have concepts (economical prediction) < Exemplar models depend on how you compute similarity
Concepts as theories
Murphy & Medin
P Theory as glue that holds concept together
P Theory as whatever principles tell you which
properties should be important, which
unimportant
< And WHY! < That is, they tell you how to compute similarity
Evidence for concepts as theories
P Facilitation in learning concepts (e.g., “thing that
can be used as a hammer” “prey vs. predator”)
P Ability to form ad hoc categories
P Belief in “essences” (essentialism)
P Keil “transformation” studies (children’s
concepts)
More evidence for concepts as theories
P Illusory correlation: Chapman and Chapman
P Clinicans’ diagnoses of mental disorders: Kim
and Ahn
< DSM IV: checklists of symptoms; presumably theory- free < But diagnosis is categorization < Individual clinician’s diagnosis affected by his/her theory of the disorder
Collins and Quillian expt
Reaction Time to Verify
P Propertyquestions < An oak has acorns?
- distance 0 < A spruce has branches
- distance 1 < A birch has seeds
- distance 2 P Category questions < A maple is a maple?
- distance 0 < A cedar is a tree?
- distance 1 < An elm is a plant?
- distance 2
Collins & Quillian Expts
Spreading activation
P A metaphor: a concept can be active to a greater
or lesser degree
P Its activation spreads to related concepts
P Priming
P Distance effects
P Fan experiments
Fan Experiments, phase 2
P Augmented learning materials
< Marty broke the bottle; Marty did not delay the trip; Marty was chosen to address the crowd < Herb produced sour notes; Herb realized the seam was split; Herb painted an old barn < + six more pairs
P Test phase
< Same as before: Marty broke the bottle, etc.
Fan: three links
Was chosen to address the crowd
Did not delay the trip
Broke the bottle
Marty
Fan experiments
P The time to verify the original facts was longer
when the third fact about each individual was
added
P Interpretation: The activation spreading from the
“Marty” node was divided among more other
nodes (3, not 2). Therefore these other nodes
were activated more slowly.
The paradox of the expert
P the start of the paradox: learning some material
slows you down in remembering other material
and even causes you to forget the other material
(retroactive inhibition)
< So who should have the hardest time remembering material? < well, the person who has learned the most other material – an expert! < but experts seem to have the BEST memory for a topic, not the worst