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Psy1302 Psychology of Language

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Psy1302 Psychology of Language Lecture 16 Words and Meanings II – PowerPoint PPT presentation

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Title: Psy1302 Psychology of Language


1
Psy1302 Psychology of Language
  • Lecture 16
  • Words and Meanings II

2
Review
Review Classical Theory of Concepts
  • Classical Theory of Concepts
  • Other Names
  • Defining Features Theory
  • Definitional Theory
  • Pros and Cons

3
Pros Explanatory Power
Review Classical Theory of Concepts
  1. Explains category membership in terms of
    necessary and sufficient features
  2. Allows identification of new candidates
  3. Explains how you learned the meanings of the
    words.
  4. Provides descriptions that can support semantic
    compositionality.
  5. Semantic feature can explain relationships
    between words.

4
Cons Problems for Classical Theory
Review Classical Theory of Concepts
  • Difficulty in coming up with a set of necessary
    and sufficient features
  • E.g. game, bachelor
  • Feature Naming list features of apple,
    lemon, fig.
  • Necessary and sufficient features DO NOT emerge
  • Category membership may not be ALL-OR-NONE
  • Category boundaries are fuzzy.
  • Cup vs. Bowl
  • Categories have graded membership
  • Typicality effects some members are better than
    others

5
Pro Prototype Theory(Experiments showing Graded
Membership)
Review Prototype Theory of Concepts
  • Prototypicality Ratings correlates with
    Production Task
  • (Rate 1-7 Good/Bad) (List Members)
  • Prototypical members are listed early.
  • Prototypicality Ratings correlates with
    Verification Task
  • (Rating 1-7 Good/Bad) (RT of X is a ___.)
  • Prototypical members are responded to faster.
  • Prototypicality Rating correlates with Feature
    Naming
  • (Rate 1-7 Good/Bad) (List features
    of)
  • Prototypical members share more features with
    other members.

6
Prototype Theory
Prototype Theory (Probabilistic Features)
  • Concepts are made of
  • features
  • perceptually grounded
  • (like the classical theory)
  • How are features combined
  • family resemblance no single feature necessary
  • more shared features better category member
  • (different than the classical theory)

7
One formalization ofFamily Resemblance Structure
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
  • Smith Family

8
Family Resemblance Smith family
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
  • Degree of Category Membership (Smithness)
    depends on
  • the number of features and
  • how central they are to Smithness

9
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
Family Resemblance Smith family
  • Smith Features
  • Beard 8/8 1
  • Brown hair 6/8 .75
  • Big nose 6/8 .75
  • Big ears 6/8 .75
  • Mustache 5/8 .625
  • Smith Features
  • Beard 8/8
  • Brown hair 6/8
  • Big nose 6/8
  • Big ears 6/8
  • Mustache 5/8
  • Smith Features
  • Beard
  • Brown hair
  • Big nose
  • Big ears
  • Mustache

10
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
  • Middle Smith has all features
  • beard 1 1.0
  • brown hair 1 .75
  • big nose 1 .75
  • big ears 1 .75
  • mustache 1 .625
  • ---------------------------
  • Total 3.8

11
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
  • Smith 3 a few features
  • beard 1 1.0
  • brown hair 1 .75
  • big nose 0 .75
  • big ears 1 .75
  • mustache 0 .625
  • --------------------------
  • Total 2.5
  • poorer instance than middle Smith

12
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
  • Item with too few features is not a member of the
    category
  • beard 0 1
  • brown hair 0 .75
  • big nose 1 .75
  • big ears 0 .75
  • mustache 0 .625
  • -----------------------
  • Total .75
  • not a Smith

13
One formalization ofFamily Resemblance Structure
Prototype Theory (Probabilistic Features)
Family Resemblance Structure
  • Features have associated probability
  • These probabilities may be thought of as weights
    on the features for membership/identification
    purposes
  • Category membership is based on a weighted sum of
    the features.

14
Verification Task
Prototype Theory (Probabilistic Features)
Applied to Experimental Data
  • Press a button to answer TRUE or FALSE to the
    following statements
  • Question Response
  • A canary is a bird
  • A ostrich is a bird
  • TRUE
  • TRUE

15
Prototype Theory (Rosch Mervis, 1975)
Prototype Theory (Probabilistic Features)
Applied to Experimental Data
  • Conceptual category (e.g. birds) is represented
    by a prototype
  • an average of all the exemplars in the category
  • not a real instance, just an abstraction
  • the average bird will be more like a canary
    than an ostrich
  • Verification task compare the exemplar to the
    prototype
  • A canary is a bird
  • big overlap FAST
  • An ostrich is a bird
  • small overlap SLOW

16
Prototype Theory Summary
Prototype Theory (Probabilistic Features)
  1. Certain members of a category are prototypical
    or instantiate the prototype
  2. Categories form around prototypes new members
    added on basis of resemblance to prototype
  3. No requirement that a property or set of
    properties be shared by all members
  4. Features/attributes generally gradable
  5. Category membership a matter of degree
  6. Categories do not have clear boundaries

17
Pros Explanatory power of Prototype Theory
Prototype Theory (Probabilistic Features)
  • Explains category membership ratings
  • membership is graded not absolute
  • Explains sentence verification results
  • more typical instances quickly identified because
    they have more of the category features.
  • Consistent with feature listing results
  • more typical instances have more features in
    common with other members

18
  • Hypothesis 4b Exemplar Theory
  • Alternative to prototype theory

19
Exemplar Theory
  • Conceptual category (e.g. birds) is represented
    by an instance of every exemplar
  • No single concept bird

20
Armstrong, Gleitman GleitmanStructure of the
Argument
Prototype Theory (Probabilistic Features)
PROBLEM
  • Prototype Claim
  • If a category shows typicality effects, then
  • it must have a prototype structure
  • Contrapositive
  • Whenever if A then B is true.
  • If not B, then not A must also be true.

21
Armstrong, Gleitman GleitmanStructure of the
Argument
Prototype Theory (Probabilistic Features)
PROBLEM
  • Prototype Claim
  • If a category shows typicality effects, then it
    must have a prototype structure
  • Contrapositive of Prototype Claim
  • If a category does not have a prototype structure
    then it will not show typicality effects.

22
Armstrong, Gleitman GleitmanStructure of the
Argument
Prototype Theory (Probabilistic Features)
PROBLEM
  • If you can disprove the contrapositive then the
    original claim must be false.
  • Contrapositive of Prototype Claim
  • If a category does not have a prototype structure
    then it will not show typicality effects.

23
Armstrong, Gleitman GleitmanStructure of the
Argument
Prototype Theory (Probabilistic Features)
PROBLEM
  • AGG set out to disprove the contrapositive by
    conducting typicality tests on well-defined
    categories
  • mathematical categories even number, triangle,
    plane
  • gender categories female, male
  • kinship terms uncle, grandmother
  • Contrapositive Well-defined categories (those
    that do not have prototypical structure) should
    not show typicality effect.

24
Exp. 1 Exemplar Ratings forordinary categories
Prototype Theory (Probabilistic Features)
PROBLEM
  • FRUIT
  • apple 1.3
  • strawberry 2.1
  • pineapple 2.7
  • fig 5.2
  • olive 6.4
  • SPORT
  • football 1.4
  • hockey 1.8
  • gymnastics 2.8
  • archery 4.8
  • weight-lifting 5.1

25
Exp. 1 Exemplar Ratings forwell-defined
categories
Prototype Theory (Probabilistic Features)
PROBLEM
  • FEMALE
  • mother
  • housewife
  • princess
  • policewoman
  • comedienne
  • EVEN NUMBER
  • 4
  • 8
  • 18
  • 34
  • 106
  • EVEN NUMBER
  • 4 1.1
  • 8 1.5
  • 18 2.6
  • 34 3.4
  • 106 3.9
  • FEMALE
  • mother 1.7
  • housewife 2.4
  • princess 3.0
  • policewoman 3.9
  • comedienne 4.5

26
Verification Task
Prototype Theory (Probabilistic Features)
PROBLEM
Ordinary Well-defined
Proto (orange-fruit) (8-even)
-Proto (fig-fruit) (56-even)
27
Armstrong, Gleitman GleitmanConclusion
Prototype Theory (Probabilistic Features)
PROBLEM
  • Since well-defined categories also show
    typicality effects
  • then the presence of these effects, does not
    prove that ordinary categories have a prototype
    structure

28
Dual Theory
  • Hypothesis 5 Dual Theory
  • Dual Route Classical and Prototype

29
Grandmothers
Dual Theory
30
Dual Theory
Dual Theory
  • Definitional Features for reasoning with words
    and determining category membership
  • Who is a grandmother?
  • The mother of a parent
  • Prototypes for quick identification
  • How do you find a grandmother is a crowd?
  • look for the prototypical features
  • (kindly, gray-haired)

31
SNL Women?
Dual Theory
J. Reno
                                                                       
Pat
Mango
Tina Fey
32
Challenges for any feature theory
General Challenges
  • What are the features which determine category
    membership?
  • What are the rules which describe how meanings
    combine.

33
Classical Theory(definitional)
General Challenges
  • PET
  • animal
  • kept for amusement

34
Classical Theory(definitional)
General Challenges
  • FISH
  • aquatic
  • water-breathing
  • cold blooded
  • chambered heart
  • animal

35
Classical Theory(definitional)
General Challenges
  • PET FISH
  • aquatic
  • water-breathing
  • cold blooded
  • chambered heart
  • animal
  • kept for amusement

36
Prototype Theory
General Challenges
  • PET
  • animal
  • kept for amusement
  • cute
  • friendly
  • mammal
  • furry
  • smallish

37
Prototype Theory
General Challenges
  • FISH
  • aquatic
  • water-breathing
  • cold blooded
  • chambered heart
  • animal
  • elongated
  • spindle shaped
  • broad caudal fin

38
Prototype Theory
General Challenges
  • Predicted Prototype for Pet Fish
  • a catlike trout?
  • a fuzzy salmon?

39
Prototype Theory
General Challenges
  • Rating Task
  • Is guppy a good PET?
  • Is guppy a good FISH?
  • Is guppy a good PET FISH?
  • Rating Task
  • Is guppy a good PET? Bad Member
  • Is guppy a good FISH? Bad Member
  • Is guppy a good PET FISH? Good Member

40
General Challenges
  • A theory of concepts should explain how words
    combine to yield the meanings of phrases.
  • Prototype Theory fails to do this

41
More challenges(for any feature theory)
General Challenges
  • Differing inferences
  • SKILLFUL SURGEON
  • SKILLFUL CARPENTER
  • (is skillful adding the same features in each
    case?)
  • Feature eating modifiers
  • STONE LION
  • COUNTERFEIT DOLLAR
  • FORMER SENATOR

animate
legal tender
member of congress
42
Challenges for any feature theory
General Challenges
  • What are the features which determine category
    membership?
  • What are the rules which describe how meanings
    combine.

43
Are these any of these features necessary?
General Challenges
  • TIGER
  • JUNGLE-DWELLING
  • 4-LEGGED
  • FUR-COVERED
  • GROWLY
  • FIERCE
  • STRIPPED
  • ANIMAL

What if it lives in a zoo?
What if it lost a leg in an accident?
What if I shaved it?
What if it lost its voice?
What if it is a scaredy cat?
What if I dye its hair?
44
What is necessary?
General Challenges
  • Has tiger DNA?
  • Has tiger essence?
  • What the experts call a tiger?
  • But how can these be reduced to sensory
    primitives?

45
Are these any of these features sufficient?
General Challenges
  • What if I transplanted a mean striped tomcat to
    the jungle?
  • JUNGLE-DWELLING
  • 4-LEGGED
  • FUR-COVERED
  • GROWLY
  • FIERCE
  • STRIPPED
  • ANIMAL

46
Doctors took a raccoon and shaved away some of
its fur. They dyed what was left all black. Then
they bleached a single stripe all white down the
center of tits back. Then, with surgery, they put
in its body a sac of super smelly yucky stuff,
just like a skunk has. When they were all done,
the animal looked like this. After the operation,
was this a skunk or a raccoon?
47
Doctors took a coffeepot that looked like this.
They sawed off the handle, sealed the top, took
off the top knob, closed the spout, and sawed it
off. They also sawed off the base and attached a
flat piece of metal. They attached a
little stick, cut a window in it, and filled the
metal container with bird food. When they
were done, it looked like this After the
operation, was this a coffeepot or a birdfeeder?
48
Results
49
Results
  • Children know that appearances aren't everything.
  • Animal generalizations should be based on
    membership in a category, not on appearance.
  • This ability increases with age.
  • Children also shift from using characteristic
    properties to categorize to using defining ones.

50
Hypothesis 6 Theory-Based Theory of Concepts
Theory-Based Theory (Theory Theory)
(Theory theory)
  • Concepts are representations whose structure
    consists in their relations to other concepts as
    specified by a mental theory

51
Hypothesis 6 Theory-Based Theory
Theory-Based Theory (Theory Theory)
(Theory theory) Causal theory of category
membership.
52
Theory Theory
Theory-Based Theory (Theory Theory)
  • Causal knowledge is critical to concept learning
    in at least three ways
  • Causal knowledge helps us decide which features
    are relevant to category membership
  • Causal knowledge helps us decide which features
    are central and which peripheral.
  • Causal knowledge affects our intuitions about
    when category members will retain their identity
    and when they will be transformed.

53
Some Challenges for Theory Theory
Theory-Based Theory (Theory Theory)
  • What qualifies as a theory?
  • It is possible to have a concept, even if your
    theory is deficient or wrong?
  • The content of a concept changes when the theory
    changes
  • How do theories change?

54
A Childs TheoryExample from Callahan Oakes
(1992)
Theory-Based Theory (Theory Theory)
  • Situation It was bedtime Child is 4 yrs 2 mon.
    (42)
  • Child Why does Daddy, James (big brother), and
    me have blue eyes and you have green eyes?
  • Mother (Told her she got her eyes from Daddy.
    Then said goodnight and left the room.)
  • Child (child calls mother back 5 minutes later)
    I like Pee Wee Herman and I have blue eyes. Daddy
    likes Pee Wee Herman and he has blue eyes. James
    likes Pee Wee Herman and he has blue eyes. If you
    liked Pee Wee Herman you could get blue eyes too.

55
A Childs TheoryExample from Callahan Oakes
(1992)
Theory-Based Theory (Theory Theory)
  • Mother (I told her it would take more than
    liking Pee Wee Herman to make my eyes blue. I
    realized that she didnt understand me, so I
    explained that God gave me this color and that
    they couldnt be changed.)
  • Child Could you try to like Pee Wee Herman so we
    could see if your eyes turn blue?
  • Mother (I said I would think about it, but if my
    eyes stayed green it was ok.)

56
Concepts
Recapitulation Where we started
  • A word denotes a concept
  • Word meaning (lexical concepts)
  • Combination of words could get you more complex
    concepts
  • Categorization psychological application of a
    concept

57
Theories of Concepts
Recapitulation Where we started and what we
discussed
  • Meaning as Reference
  • Meaning as Ideas
  • Classical Theory of Concepts
  • (Defining Features Representation)
  • Prototype Theory
  • (Probabilistic Feature Representation)
  • Dual Theory
  • (Both Classical and Prototype)
  • Theory Theory of Concepts
  • (Theory-based representations)

These theories differ mostly in what they
consider the structure of concepts to be
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