Psy1302 Psychology of Language Lecture 16 Words and Meanings II

Psy1302 Psy1302 Psychology of Psychology of LanguageLanguage

Lecture 16Lecture 16

Words and Meanings IIWords and Meanings II

ReviewReview

Classical Theory of ConceptsClassical Theory of Concepts– Other Names:Other Names:

Defining Features TheoryDefining Features Theory Definitional TheoryDefinitional Theory

– Pros and ConsPros and Cons

Review: Classical Theory of Concepts

Pros: Explanatory PowerPros: Explanatory Power

1.1. Explains category membership in terms of Explains category membership in terms of necessary and sufficient featuresnecessary and sufficient features

2.2. Allows identification of new candidatesAllows identification of new candidates

3.3. Explains how you learned the meanings of Explains how you learned the meanings of the words.the words.

4.4. Provides descriptions that can support Provides descriptions that can support semantic compositionality. semantic compositionality.

5.5. Semantic feature can explain relationships Semantic feature can explain relationships between words.between words.


Cons: Problems for Classical Cons: Problems for Classical Theory Theory

Difficulty in coming up with a set of necessary and Difficulty in coming up with a set of necessary and sufficient featuressufficient features– E.g. game, bachelorE.g. game, bachelor– Feature Naming: list features of “apple”, “lemon”, “fig”. Feature Naming: list features of “apple”, “lemon”, “fig”.

Necessary and sufficient features DO NOT emergeNecessary and sufficient features DO NOT emerge

Category membership may not be ALL-OR-NONECategory membership may not be ALL-OR-NONE– Category boundaries are fuzzy. Category boundaries are fuzzy.

Cup vs. BowlCup vs. Bowl

Categories have Categories have graded membershipgraded membership– Typicality effects: some members are better than othersTypicality effects: some members are better than others


Pro Prototype TheoryPro Prototype Theory(Experiments showing Graded (Experiments showing Graded Membership)Membership)

Prototypicality Ratings correlates with Production Task Prototypicality Ratings correlates with Production Task

(Rate 1-7 Good/Bad)(Rate 1-7 Good/Bad) (List Members)(List Members)– Prototypical members are listed early.Prototypical members are listed early.

Prototypicality Ratings correlates with Verification TaskPrototypicality Ratings correlates with Verification Task

(Rating 1-7 Good/Bad)(Rating 1-7 Good/Bad) (RT of X is a ___.)(RT of X is a ___.)– Prototypical members are responded to faster.Prototypical members are responded to faster.

Prototypicality Rating correlates with Feature NamingPrototypicality Rating correlates with Feature Naming

(Rate 1-7 Good/Bad)(Rate 1-7 Good/Bad) (List features of…) (List features of…)– Prototypical members share more features with other Prototypical members share more features with other

members.members.

Review: Prototype Theory of Concepts

Prototype TheoryPrototype Theory Concepts are made of:Concepts are made of:

– featuresfeatures– perceptually groundedperceptually grounded(like the classical theory)(like the classical theory)

How are features combined:How are features combined:– family resemblance: no single feature family resemblance: no single feature

necessarynecessary– more shared features = better category more shared features = better category

membermember(different than the classical theory)(different than the classical theory)

Prototype Theory (Probabilistic Features)

One formalization ofOne formalization ofFamily Resemblance Family Resemblance StructureStructure

Smith FamilySmith Family

Prototype Theory (Probabilistic Features) – Family Resemblance Structure

Degree of Category Degree of Category Membership Membership (“Smithness”) depends (“Smithness”) depends on on – the number of features the number of features

and and – how central they are to how central they are to

“Smithness”“Smithness”

Family Resemblance Family Resemblance “Smith” family“Smith” family


Smith FeaturesSmith Features– Beard Beard 8/88/8 = 1 = 1– Brown hairBrown hair 6/8 6/8 = .75= .75– Big noseBig nose 6/8 6/8 = .75= .75– Big earsBig ears 6/8 6/8

= .75= .75– MustacheMustache 5/8 5/8 = .625= .625

Smith FeaturesSmith Features– Beard Beard 8/8 8/8 – Brown hairBrown hair 6/8 6/8 – Big noseBig nose 6/86/8– Big earsBig ears 6/86/8– MustacheMustache 5/85/8

Smith FeaturesSmith Features– Beard Beard – Brown hairBrown hair– Big noseBig nose– Big earsBig ears– MustacheMustache


Family Resemblance Family Resemblance “Smith” family“Smith” family

Middle Smith has all Middle Smith has all featuresfeatures– beard 1 * 1.0beard 1 * 1.0– brown hair 1 *.75brown hair 1 *.75– big nose 1 * .75big nose 1 * .75– big ears 1 * .75big ears 1 * .75– mustache 1* .625mustache 1* .625

------------------------------------------------------– Total 3.8Total 3.8


Smith #3 a few featuresSmith #3 a few features– beard 1* 1.0beard 1* 1.0– brown hair 1* .75brown hair 1* .75– big nose 0 * .75big nose 0 * .75– big ears 1 * .75big ears 1 * .75– mustache 0 * .625mustache 0 * .625

----------------------------------------------------– Total 2.5Total 2.5– poorer instance than poorer instance than

middle Smithmiddle Smith


Item with too few features Item with too few features is not a member of the is not a member of the categorycategory– beard 0* 1beard 0* 1– brown hair 0 * .75brown hair 0 * .75– big nose 1 * .75big nose 1 * .75– big ears 0 * .75big ears 0 * .75– mustache 0 * .625mustache 0 * .625

----------------------------------------------– Total .75Total .75– not a Smithnot a Smith


One formalization ofOne formalization ofFamily Resemblance Family Resemblance StructureStructure Features have associated probabilityFeatures have associated probability

These probabilities may be thought These probabilities may be thought of as weights on the features for of as weights on the features for membership/identification purposesmembership/identification purposes

Category membership is based on a Category membership is based on a weighted sum of the features.weighted sum of the features.


Press a button to answer Press a button to answer TRUETRUE or or FALSEFALSE to the following to the following statementsstatements

QuestionQuestion ResponseResponseA canary is a bird A canary is a bird

A ostrich is a birdA ostrich is a bird

TRUETRUE TRUETRUE

fastslow

Typicality effect

Verification TaskVerification Task

Prototype Theory (Probabilistic Features) – Applied to Experimental Data

Prototype TheoryPrototype Theory (Rosch & Mervis, (Rosch & Mervis,

1975)1975) Conceptual category (e.g. Conceptual category (e.g. birdsbirds) is represented by a ) is represented by a

prototypeprototype– an average of all the exemplars in the categoryan average of all the exemplars in the category– not a real instance, just an not a real instance, just an abstractionabstraction– the ‘average bird’ will be more like a canary than an ostrichthe ‘average bird’ will be more like a canary than an ostrich

Verification task: Verification task: compare the exemplar to the compare the exemplar to the prototype prototype – A canary is a birdA canary is a bird

big overlap = big overlap = FASTFAST

– An ostrich is a birdAn ostrich is a bird small overlap = small overlap = SLOWSLOW

Typicality effect!

= ?

= ?

Prototype Theory (Probabilistic Features) – Applied to Experimental Data

Prototype Theory SummaryPrototype Theory Summary

1.1. Certain members of a category are Certain members of a category are prototypical – or instantiate the prototypeprototypical – or instantiate the prototype

2.2. Categories form around prototypes; new Categories form around prototypes; new members added on basis of resemblance to members added on basis of resemblance to prototypeprototype

3.3. No requirement that a property or set of No requirement that a property or set of properties be shared by all membersproperties be shared by all members

4.4. Features/attributes generally gradableFeatures/attributes generally gradable

5.5. Category membership a matter of degreeCategory membership a matter of degree

6.6. Categories do not have clear boundariesCategories do not have clear boundaries


Pros: Explanatory power of Pros: Explanatory power of Prototype TheoryPrototype Theory

Explains category membership Explains category membership ratingsratings– – membership is graded not absolutemembership is graded not absolute

Explains sentence verification results:Explains sentence verification results:– more typical instances quickly identified more typical instances quickly identified

because they have more of the category because they have more of the category features.features.

Consistent with feature listing resultsConsistent with feature listing results– – more typical instances have more more typical instances have more

features in common with other membersfeatures in common with other members


Armstrong, Gleitman & Armstrong, Gleitman & GleitmanGleitmanStructure of the ArgumentStructure of the Argument

Prototype Claim:Prototype Claim:

If If a category shows a category shows typicality typicality effectseffects, then, then

it must have a it must have a prototype structureprototype structure

Contrapositive:Contrapositive:

Whenever “if Whenever “if AA then then BB” is true.” is true.

““If If not Bnot B, then , then not Anot A” must also be true.” must also be true.

AB

Prototype Theory (Probabilistic Features) – PROBLEM


Prototype Claim:Prototype Claim: If If a category shows a category shows typicality effectstypicality effects, ,

then then it must have a it must have a prototype structureprototype structure

Contrapositive of Prototype Claim:Contrapositive of Prototype Claim: If a category does not have If a category does not have a prototype a prototype

structurestructure then it will not show then it will not show typicality effectstypicality effects..

AB



If you can disprove the contrapositive If you can disprove the contrapositive then the original claim must be false.then the original claim must be false.

Contrapositive of Prototype Claim:Contrapositive of Prototype Claim: If a category does not have If a category does not have a a

prototype structureprototype structure then it will not then it will not show show typicality effectstypicality effects..

AB



AGG set out to disprove the contrapositive AGG set out to disprove the contrapositive by conducting typicality tests on well-by conducting typicality tests on well-defined categories:defined categories:– mathematical categories: even number, mathematical categories: even number,

triangle, planetriangle, plane– gender categories: female, malegender categories: female, male– kinship terms: uncle, grandmotherkinship terms: uncle, grandmother

Contrapositive: Well-defined categories Contrapositive: Well-defined categories (those that do not have prototypical (those that do not have prototypical structure) should not show typicality effect.structure) should not show typicality effect.


Exp. 1: Exemplar Ratings Exp. 1: Exemplar Ratings forforordinary categoriesordinary categoriesFRUITFRUIT apple apple 1.31.3 strawberry strawberry 2.12.1 pineapple pineapple 2.72.7 fig fig 5.25.2 olive olive 6.46.4

SPORTSPORT football football 1.41.4 hockey hockey 1.81.8 gymnastics gymnastics 2.82.8 archery archery 4.84.8 weight-lifting weight-lifting 5.15.1


FEMALEFEMALE mother mother housewife housewife princess princess policewoman policewoman comedienne comedienne

EVEN NUMBEREVEN NUMBER 4 4 8 8 18 18 34 34 106 106

Exp. 1: Exemplar Ratings Exp. 1: Exemplar Ratings forforwell-defined categorieswell-defined categoriesEVEN NUMBEREVEN NUMBER 4 4 1.11.1 8 8 1.51.5 18 18 2.62.6 34 34 3.43.4 106 106 3.93.9

FEMALEFEMALE mother mother 1.71.7 housewife housewife 2.42.4 princess princess 3.03.0 policewoman policewoman 3.93.9 comedienne comedienne 4.54.5


Verification TaskVerification Task

OrdinaryOrdinary Well-definedWell-defined

+Proto+Proto (orange-fruit)(orange-fruit) (8-even)(8-even)

-Proto-Proto (fig-fruit)(fig-fruit) (56-even)(56-even)

Fast

Slow

Fast

Slow> >


Armstrong, Gleitman & Armstrong, Gleitman & GleitmanGleitmanConclusionConclusion Since well-defined categories also Since well-defined categories also

show typicality effectsshow typicality effects then the presence of these then the presence of these

effects, does not prove that effects, does not prove that ordinary categories have a ordinary categories have a prototype structureprototype structure


Hypothesis 5: Dual TheoryHypothesis 5: Dual Theory– Dual Route: Classical and PrototypeDual Route: Classical and Prototype

Dual Theory

GrandmothersGrandmothers

Dual Theory

Dual TheoryDual Theory

Definitional Definitional Features for Features for reasoning with reasoning with words and words and determining determining category category membershipmembership

Who is a Who is a grandmother?grandmother?– The mother of a The mother of a

parentparent

Prototypes for Prototypes for quick identificationquick identification

How do you find a How do you find a grandmother is a grandmother is a crowd?crowd?

look for the look for the prototypical prototypical featuresfeatures– (kindly, gray-(kindly, gray-

haired)haired)

Dual Theory

Mango

Pat

Tina Fey

J. Reno

SNL Women?SNL Women?Dual Theory

Challenges for any feature Challenges for any feature theorytheory

1.1. What are the features which What are the features which determine category determine category membership?membership?

2.2. What are the rules which What are the rules which describe how meanings describe how meanings combine.combine.

General Challenges

Classical TheoryClassical Theory(definitional)(definitional)

PETPET [animal][animal] [kept for [kept for

amusement]amusement]

General Challenges


FISHFISH [aquatic][aquatic] [water-breathing][water-breathing] [cold blooded][cold blooded] [chambered heart][chambered heart] [animal][animal]

General Challenges


PETPET ++ FISHFISH [aquatic][aquatic] [water-breathing][water-breathing] [cold blooded][cold blooded] [chambered heart][chambered heart] [animal][animal] [kept for [kept for

amusement]amusement]

General Challenges

Prototype TheoryPrototype Theory

PETPET [animal][animal] [kept for [kept for

amusement]amusement] [cute][cute] [friendly][friendly] [mammal][mammal] [furry][furry] [smallish][smallish]

General Challenges


FISHFISH [aquatic][aquatic] [water-breathing][water-breathing] [cold blooded][cold blooded] [chambered heart][chambered heart] [animal][animal] [elongated][elongated] [spindle shaped][spindle shaped] [broad caudal fin][broad caudal fin]

General Challenges

Prototype TheoryPrototype Theory Predicted Predicted

Prototype for Prototype for PetPet FishFish::– a catlike trout?a catlike trout?– a fuzzy salmon?a fuzzy salmon?

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

General Challenges

A theory of concepts should A theory of concepts should explain how words combine to explain how words combine to yield the meanings of phrases.yield the meanings of phrases.

Prototype Theory fails to do thisPrototype Theory fails to do this

General Challenges

Differing inferences:Differing inferences:– SKILLFUL + SURGEONSKILLFUL + SURGEON– SKILLFUL + CARPENTERSKILLFUL + CARPENTER(is skillful adding the same features in (is skillful adding the same features in

each case?)each case?) Feature eating modifiersFeature eating modifiers

– STONE LION:STONE LION:– COUNTERFEIT DOLLAR: COUNTERFEIT DOLLAR: – FORMER SENATOR: FORMER SENATOR:

More challenges…More challenges…(for any feature theory)(for any feature theory)

General Challenges

[animate][legal tender]

[member of congress]

Challenges for any feature Challenges for any feature theorytheory

1.1. What are the features which What are the features which determine category determine category membership?membership?

2.2. What are the rules which What are the rules which describe how meanings describe how meanings combine.combine.

General Challenges

Are these any of these Are these any of these features necessary?features necessary?TIGERTIGER [JUNGLE-DWELLING][JUNGLE-DWELLING] [4-LEGGED][4-LEGGED] [FUR-COVERED][FUR-COVERED] [GROWLY][GROWLY] [FIERCE][FIERCE] [STRIPPED][STRIPPED] [ANIMAL][ANIMAL]

General Challenges

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?

What is necessary?What is necessary?

Has tiger DNA?Has tiger DNA? Has tiger essence?Has tiger essence? What the experts call a tiger?What the experts call a tiger?

But how can these be reduced to But how can these be reduced to sensory primitives?sensory primitives?

General Challenges

Are these any of these Are these any of these features sufficient?features sufficient?

What if I transplanted a mean striped tomcat What if I transplanted a mean striped tomcat to the jungle?to the jungle?

[JUNGLE-DWELLING][JUNGLE-DWELLING] [4-LEGGED][4-LEGGED] [FUR-COVERED][FUR-COVERED] [GROWLY][GROWLY] [FIERCE][FIERCE] [STRIPPED][STRIPPED] [ANIMAL][ANIMAL]

General Challenges

Doctors took a raccoon andshaved away some of its fur.They dyed what was left allblack. Then they bleached asingle stripe all white downthe center of tits back. Then,with surgery, they put in itsbody a sac of super smellyyucky stuff, just like a skunkhas. When they were alldone, the animal looked likethis.After the operation, was thisa skunk or a raccoon?

Doctors took a coffeepot thatlooked like this. They sawedoff the handle, sealed the top,took off the top knob, closedthe spout, and sawed it off.They also sawed off the baseand attached a flat piece ofmetal. They attached a littlestick, cut a window in it, andfilled the metal container withbird food. When they weredone, it looked like thisAfter the operation, was this acoffeepot or a birdfeeder?

ResultsResults

ResultsResults

Children know that appearances Children know that appearances aren't everything.aren't everything.

Animal generalizations should be Animal generalizations should be based on membership in a based on membership in a category, not on appearance.category, not on appearance.

This ability increases with age.This ability increases with age. Children also shift from using Children also shift from using

characteristic properties to characteristic properties to categorize to using defining ones.categorize to using defining ones.

(Theory theory)

Hypothesis 6: Theory-Based Hypothesis 6: Theory-Based Theory of ConceptsTheory of Concepts

Concepts are representations whose structure consists in their relations to other concepts as specified by a mental theory

Theory-Based Theory (Theory Theory)

Hypothesis 6: Theory-Based Hypothesis 6: Theory-Based TheoryTheory


(Theory theory)Causal theory of category membership.

Theory TheoryTheory Theory

Causal knowledge is critical to concept Causal knowledge is critical to concept learning in at least three ways: learning in at least three ways: – Causal knowledge helps us decide which Causal knowledge helps us decide which

features are relevant to category features are relevant to category membership membership

– Causal knowledge helps us decide which Causal knowledge helps us decide which features are central and which peripheral. features are central and which peripheral.

– Causal knowledge affects our intuitions about Causal knowledge affects our intuitions about when category members will retain their when category members will retain their identity and when they will be transformed. identity and when they will be transformed.


Some Challenges for Theory Some Challenges for Theory TheoryTheory

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?


A Child’s TheoryA Child’s TheoryExample from Callahan & Oakes Example from Callahan & Oakes (1992)(1992)

Situation: It was bedtime & Child is 4 yrs 2 mon. (4;2)

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.


A Child’s TheoryA Child’s TheoryExample from Callahan & Oakes Example from Callahan & Oakes (1992)(1992)

Mother: (I told her it would take more than liking Pee Wee Herman to make my eyes blue. I realized that she didn’t understand me, so I explained that God gave me this color and that they couldn’t 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.)


ConceptsConcepts

A word denotes a concept Word meaning (lexical concepts) Combination of words could get

you more complex concepts Categorization = psychological

application of a concept

Recapitulation: Where we started

Theories of ConceptsTheories of Concepts

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

Recapitulation: Where we started and what we discussed

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Psy1302 Psychology of Language Lecture 16 Words and Meanings II