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Categories and concepts- introduction. CS182/Ling109/CogSci110 Spring 2007. Lecture Outline. Categories Basic Level Prototype Effects Neural Evidence for Category Structure Aspects of a Neural Theory of concepts Image Schemas Description and types Behavioral Experiment on Image Schemas

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Categories and concepts introduction l.jpg

Categories and concepts- introduction

CS182/Ling109/CogSci110

Spring 2007


Lecture outline l.jpg

Lecture Outline

  • Categories

    • Basic Level

    • Prototype Effects

    • Neural Evidence for Category Structure

  • Aspects of a Neural Theory of concepts

  • Image Schemas

    • Description and types

    • Behavioral Experiment on Image Schemas

  • Event Structure and Motor Schemas


Embodiment l.jpg

Embodiment

Of all of these fields, the learning of languages would be the most impressive, since it is the most human of these activities. This field, however, seems to depend rather too much on the sense organs and locomotion to be feasible.

Alan Turing (Intelligent Machines,1948)


The wcs color chips l.jpg

The WCS Color Chips

  • Basic color terms:

    • Single word (not blue-green)

    • Frequently used (not mauve)

    • Refers primarily to colors (not lime)

    • Applies to any object (not blonde)


Concepts l.jpg

Concepts

  • What Concepts Are: Basic Constraints

    • Concepts are the elements of reason, and

    • constitute the meanings of words and linguistic expressions.


Slide6 l.jpg

  • Concepts Are:

  • Universal: they characterize all particular instances; e.g., the concept of grasping is the same no matter who the agent is or what the patient is or how it is done.

  • Stable.

  • Internally structured.

  • Compositional.

  • Inferential. They interact to give rise to inferences.

  • Relational. They may be related by hyponymy, antonymy, etc.

  • Meaningful.

  • Not tied to the specific words used to express them.


Concepts traditional theory l.jpg

Concepts: Traditional Theory

  • The Traditional Theory

    • Reason and language are what distinguish human beings from other animals.

    • Concepts therefore use only human-specific brain mechanisms.

    • Reason is separate from perception and action, and does not make direct use of the sensory-motor system.

    • Concepts must be “disembodied” in this sense.


The neural theory l.jpg

The neural theory

Human concepts are embodied. Many concepts make direct use of sensory-motor, emotional, and social cognition capacities of our body-brain system.

  • Many of these capacities are also present in non-human primates.


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Classical vs prototype model of categorization

  • Classical model

    • Category membership determined on basis of essential features

    • Categories have clear boundaries

    • Category features are binary

  • Prototype model

    • Features that frequently co-occur lead to establishment of category

    • Categories are formed through experience with exemplars


Prototype theory l.jpg

Prototype theory

  • Certain members of a category are prototypical – or instantiate the prototype

  • Categories form around prototypes; new members added on basis of resemblance to prototype

  • No requirement that a property or set of properties be shared by all members

  • Features/attributes generally gradable

  • Category membership a matter of degree

  • Categories do not have clear boundaries


Prototype theory11 l.jpg

Prototype theory

  • Certain members of a category are prototypical – or instantiate the prototype

    Category members are not all equal

    a robin is a prototypical bird, but we may not want to say it is the prototype, rather it instantiates (manifests) the prototype or ideal -- it exhibits many of the features that the abstract prototype does

    “It is conceivable that the prototype for dog will be unspecified for sex; yet each exemplar is necessarily either male or female.” (Taylor)


Prototype theory12 l.jpg

Prototype theory

3.No requirement that a property or set of properties be shared by all members -- no criterial attributes

  • Category where a set of necessary and sufficient attributes can be found is the exception rather than the rule

  • Labov household dishes experiment

    • Necessary that cups be containers, not sufficient since many things are containers

    • Cups can’t be defined by material used, shape, presence of handles or function

    • Cups vs. bowls is graded and context dependent


Prototype theory13 l.jpg

Prototype theory

  • Wittgenstein’s examination of game

    • Generally necessary that all games be amusing, not sufficient since many things are amusing

    • Board games, ball games, card games, etc. have different objectives, call on different skills and motor routines

      - categories normally not definable in terms of necessary and sufficient features


Prototype theory14 l.jpg

Prototype theory

  • What about mathematical categories like odd or even numbers? Aren’t these sharply defined?

    • (Armstrong et al.) Subjects asked to assign numbers a degree of membership to the categories odd number or even number

       3 had a high degree of membership, 447 and 91 had a lower degree (all were rated at least ‘moderately good’)


Categories who decides l.jpg

Categories - who decides?

  • Embodied theory of meaning- categories are not pre-formed and waiting for us to behold them. Our need for categories drives what categories we will have

  • Basic level categories - not all categories have equal status. The basic level category has demonstrably greater psychological significance.


Basic level categories l.jpg

Basic-level categories


Slide17 l.jpg

chair desk chair

easy chair rocking chair

furniture lamp desk lamp

floor lamp

table dining room table coffee table

Superordinate Basic Subordinate


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Categories & Prototypes: Overview

Furniture

Superordinate

  • Three ways of examining the categories we form:

    • relations between categories (e.g. basic-level category)

    • internal category structure (e.g. radial category)

    • instances of category members (e.g. prototypes)

Sofa

Desk

Basic-Level Category

leathersofa

fabricsofa

L-shapeddesk

Receptiondisk

Subordinate


Basic level criteria l.jpg

Basic-level -- Criteria

  • Perception –

    • overall perceived shape

    • single mental image

    • fast identification


Basic level criteria20 l.jpg

Basic-level -- Criteria

  • Perception

  • Function – motor program for interaction


Basic level criteria21 l.jpg

Basic-level -- Criteria

  • Perception

  • Function

  • Words –

    • shortest

    • first learned by children

    • first to enter lexicon


Basic level criteria22 l.jpg

Basic-level -- Criteria

  • Perception

  • Function

  • Communication

  • Knowledge organization –

    • most attributes are stored at this level


Basic level category l.jpg

Perception:

similar overall perceived shape

single mental image

(gestalt perception)

fast identification

Function:

general motor program

Communication:

shortest

most commonly used

contextually neutral

first to be learned by children

first to enter the lexicon

Knowledge Organization:

most attributes of category members stored at this level

Basic-Level Category

What constitutes a basic-level category?


Other basic level categories l.jpg

Other Basic-level categories

  • Objects

  • Colors

  • Motor-routines


Concepts are not categorical l.jpg

Concepts are not categorical


Mother l.jpg

Mother

  • The birth model

    The person who gives birth is the mother

  • The genetic model

    The female who contributes the genetic material is the mother

  • The nurturance model

    The female adult who nurtures and raises a child is the mother of the child

  • The marital model

    The wife of the father is the mother

  • The genealogical model

    The closest female ancestor is the mother

(WFDT Ch.4, p.74, p.83)


Radial structure of mother l.jpg

Radial Structure of Mother

Geneticmother

Stepmother

The radial structure of this category is defined with respect to the different models

Unwedmother

Adoptivemother

CentralCase

Surrogatemother

Birthmother

Biologicalmother

Naturalmother

Fostermother


Marriage l.jpg

Marriage

  • What is a marriage?

  • What are the frames (or models) that go into defining a marriage?

  • What are prototypes of marriage?

  • What metaphors do we use to talk about marriages?

  • Why is this a contested concept right now?


Concepts and radial categories l.jpg

Concepts and radial categories

Concepts can be the "prototype" of their category in various ways.

  • Central subcategory (others relate to this)

    • Amble and swagger relate to WALK

    • Shove relates to PUSH

  • Essential (meets a folk definition: birds have feathers, lay eggs)

    • Move involves change of location.

  • Typical case (most are like this: "sparrow")

    • Going to a conference involves air travel.

  • Ideal/anti-ideal case (positive social standard: "parent"); anti-ideal case (negative social standard: "terrorist")

  • Stereotype (set of attributes assumed in a culture: "Arab")

  • Salient exemplar (individual chosen as example)


  • Category structure l.jpg

    Category Structure

    • Classical Category:

      • necessary and sufficient conditions

    • Radial Category:

      • a central member branching out to less-central and non-central cases

      • degrees of membership, with extendable boundary

    • Family Resemblance:

      • every family member “looks” like some other family member(s)

      • there is no one property common across all members (e.g. polysemy)

    • Prototype-Based Category

    • Essentially-Contested Category (Gallie, 1956) (e.g. democracy)

    • Ad-hoc Category (e.g. things you can fit inside a shopping bag)


    Prototype l.jpg

    Cognitive reference point

    standards of comparison

    Social stereotypes

    snap judgments

    defines cultural expectations

    challengeable

    Typical case prototypes

    default expectation

    often used unconsciously in reasoning

    Ideal case / Nightmare case

    e.g. ideal vacation

    can be abstract

    may be neither typical nor stereotypical

    Paragons / Anti-paragons

    an individual member that exhibits the ideal

    Salient examples

    e.g. 9/11 – terrorism act

    Generators

    central member + rules

    e.g. natural number = single-digit numbers + arithmetic

    Prototype


    Neural evidence for category structure l.jpg

    Neural Evidence for category structure

    • Are there specific regions in the brain to recognize/reason with specific categories?


    Category naming and deficits l.jpg

    Category Naming and Deficits

    • People with brain injury have selective deficits in their knowledge of categories.

    • Some patients are unable to identify or name man made objects and others may not be able to identify or name natural kinds (like animals)


    A pet study on categories nature 1996 l.jpg

    A PET Study on categories (Nature 1996)


    Study l.jpg

    Study

    • 16 adults (8M, 8F) participated in a PET (positron emission tomography) study.

      • Involves injecting subject with a positron emitting radioactive substance (dye)

      • Regions with more metabolic activity will absorb more of the substance and thus emit more positrons

      • Positron-electron collisions yield gamma rays, which are detected

    • Increased rCBF (regional changes in cerebral blood flow) was measured

      • When subjects viewed line drawings of animals and tools.


    The experiment l.jpg

    The experiment

    • Subjects looked at pictures of animals and tools and named them silently.

    • They also looked at noise patterns (baseline 1)

    • And novel nonsense objects (baseline 2)

    • Each stimulus was presented for 180ms followed by a fixation cross of 1820 ms.

    • Drawings were controlled for name frequency and category typicality


    Slide37 l.jpg

    Left middle temporal gyrus

    ACC

    Premotor


    Slide38 l.jpg

    Calcarine Sulcus


    Conclusions l.jpg

    Conclusions

    • Both animal and tool naming activate the ventral temporal lobe region.

    • Tools differentially activate the ACC, pre-motor and left middle temporal region (known to be related to processing action words).

    • Naming animals differentially activated left medial occipital lobe (early visual processing)

    • The object categories appear to be in a distributed circuit that involves activating different salient aspects of the category.


    Action words an fmri study l.jpg

    Action Words- an fMRI study

    • Somatotopic Representation of Action Words in Human Motor and Premotor Cortex

      • Olaf Hauk, Ingrid Johnsrude,and Friedemann Pulvermuller*

      • Medical Research Council, Cognition and Brain Sciences Unit Cambridge, United Kingdom

      • Neuron, Vol. 41, 1–20, January 22, 2004, Copyright .2004 by Cell Press


    Traditional theory l.jpg

    Traditional theory

    • Unified meaning center in the left temporal lobe.

      • Connected to Wernicke’s area

      • Experiments on highly imageable words/nouns.

    • Vocalization and grammar associated with frontal lobe

      • Connected to Broca’s area


    Do action words activate the motor cortex l.jpg

    Do action words activate the motor cortex

    • Given: Cortical representations of the face, arm, and leg are discrete and somatotopically organized in the motor and premotor cortex

    • Hypothesis: Words referring to actions performed with the face, arm, or leg would activate premotor networks.

      • neurons processing the word form and those processing the referent action should frequently fire together and thus become more strongly linked, resulting in word-related networks overlapping with motor and premotor cortex in a somatotopic fashion.

    • Experiment: An fMRI study with word stimuli from different effectors (face, arm, or leg). ROI based on movements (face, arm, leg)


    Somatotopy in sts and mc l.jpg

    Somatotopy in STS and MC


    The experiment45 l.jpg

    The Experiment

    • In order to find appropriate stimulus words, a rating study was first performed.

      • Subjects were asked to rate words according to their action and visual associations and to make explicit whether the words referred to and reminded them of leg, arm, and face movements that they could perform themselves

    • From the rated material, 50 words from each of the three semantic subcategories were selected and presented in a passive reading task to 14 right-handed volunteers, while hemodynamic activity was monitored using event-related fMRI.

    • The word groups were matched for important variables, including word length, imageability, and standardized lexical frequency, in order to minimize physical or psycholinguistic differences that could influence the hemodynamic response.

    • To identify the motor cortex in each volunteer individually, localizer scans were also performed, during which subjects had to move their left or right foot, left or right index finger, or tongue.


    Norming l.jpg

    Norming

    (B) Mean ratings for the word stimuli obtained from study participants. Subjects were asked to give ratings on a 7 point scale whether the

    words reminded them of face, arm, and leg actions. The word groups are clearly dissociated semantically (face-, arm-, and leg-related words).


    All actions l.jpg

    All Actions

    (C) Activation produced by all action words pooled together. Results are rendered on a standard brain surface (left) and on axial slices of the same brain (right).


    Movement vs actions l.jpg

    Movement vs. Actions


    Correlation with bold signal l.jpg

    Correlation with BOLD Signal


    Neural evidence for category structure51 l.jpg

    Neural Evidence for category structure

    • Are there specific regions in the brain to recognize/reason with specific categories?

    • No, but there are specific circuits distributed over relevant regions of the brain.


    What are schemas l.jpg

    What are schemas?

    • Regularities in our perceptual, motor and cognitive systems

    • Structure our experiences and interactions with the world.

    • May be grounded in a specific cognitive system, but are not situation-specific in their application (can apply to many domains of experience)


    Basis of image schemas l.jpg

    Basis of Image schemas

    • Perceptual systems

    • Motor routines

    • Social Cognition

    • Image Schema properties depend on

      • Neural circuits

      • Interactions with the world


    Image schemas l.jpg

    boundary

    bounded region

    Image schemas

    LM

    • Trajector / Landmark (asymmetric)

      • The bike is near the house

      • ? The house is near the bike

    • Boundary / Bounded Region

      • a bounded region has a closed boundary

    • Topological Relations

      • Separation, Contact, Overlap, Inclusion, Surround

    • Orientation

      • Vertical (up/down), Horizontal (left/right, front/back)

      • Absolute (E, S, W, N)

    TR


    Slide55 l.jpg

    Similarity:

    • Perceptual and motor systems

    • Basic functional interactions with the world

    • Environment

      Variation:

      Cross-linguistic variation in how schemas are used.


    Cross linguistic variations l.jpg

    Cross-linguistic Variations


    English l.jpg

    English


    Japanese l.jpg

    Japanese


    English59 l.jpg

    AROUND

    ON

    IN

    OVER

    English

    Bowerman & Pederson


    Dutch l.jpg

    OP

    OM

    AAN

    IN

    BOVEN

    Dutch

    Bowerman & Pederson


    Chinese l.jpg

    ZHOU

    LI

    SHANG

    Chinese

    Bowerman & Pederson


    Spatial schemas l.jpg

    Spatial schemas

    • TR/LM relation

    • Boundaries, bounded region

    • Topological relations

    • Orientational Axes

    • Proximal/Distal


    Trajector landmark schema l.jpg

    Trajector/Landmark Schema

    • Roles:

      Trajector (TR) – object being located

      Landmark (LM) – reference object

      TR and LM may share a location (at)


    Tr lm asymmetry l.jpg

    TR/LM -- asymmetry

    • The cup is on the table

    • ?The table is under the cup.

    • The skateboard is next to the post.

    • ?The post is next to the skateboard.


    Boundary schema l.jpg

    Boundary Schema

    Roles:

    Boundary

    Region A

    Region B

    Region A

    Region B

    Boundary


    Bounded region l.jpg

    Bounded Region

    Roles:

    Boundary: closed

    Bounded Region

    Background region


    Topological relations l.jpg

    Topological Relations

    • Separation


    Topological relations68 l.jpg

    Topological Relations

    • Separation

    • Contact


    Topological relations69 l.jpg

    Topological Relations

    • Separation

    • Contact

    • Coincidence:


    Topological relations70 l.jpg

    Topological Relations

    • Separation

    • Contact

    • Coincidence:

      - Overlap


    Topological relations71 l.jpg

    Topological Relations

    • Separation

    • Contact

    • Coincidence:

      • Overlap

      • Inclusion


    Topological relations72 l.jpg

    Topological Relations

    • Separation

    • Contact

    • Coincidence:

      • Overlap

      • Inclusion

    • Encircle/surround


    Orientation l.jpg

    Orientation

    • Vertical axis -- up/down

    up

    above

    upright

    below

    down


    Orientation74 l.jpg

    Orientation

    Horizontal plane – Two axes:


    Language and frames of reference l.jpg

    Language and Frames of Reference

    • There seem to be three prototypical frames of reference in language (Levinson)

      • Intrinsic

      • Relative

      • Absolute


    Intrinsic frame of reference l.jpg

    Intrinsic frame of reference

    left

    back

    front

    right


    Relative frame of reference l.jpg

    Relative frame of reference

    right??

    back

    front

    left??


    Absolute frame of reference l.jpg

    Absolute frame of reference

    west

    south

    north

    east


    Tr lm and verticality schemas l.jpg

    TR/LM and Verticality Schemas

    • The book is under the table.

    up

    down

    under


    Proximal distal schema l.jpg

    Proximal/Distal Schema

    .


    Simple vs complex schemas l.jpg

    Simple vs. Complex Schemas


    Container schema l.jpg

    Container Schema

    • Roles:

      • Interior: bounded region

      • Exterior

      • Boundary

    C


    Slide83 l.jpg

    TR/LM + Container

    TR

    out

    in

    C

    C

    TR


    Container schema elaborated l.jpg

    Container Schema Elaborated

    • Complexities –more roles/specifications:

      • Boundary properties

        • Strength

        • Porosity

      • Portals


    Source path goal l.jpg

    Source-Path-Goal

    Constraints:

    initial = TR at Source

    central = TR on Path

    final = TR at Goal

    Source

    Path

    Goal


    Spg simple example l.jpg

    SPG -- simple example

    She drove from the store to the gas station.

    TR = she

    Source = the store

    Goal= the gas station

    Source

    Path

    Goal


    Spg and container l.jpg

    SPG and Container

    She ran into the room.

    SPG. Source ↔ Container.Exterior

    SPG.Path ↔ Container.Portal

    SPG. Goal ↔ Container.Interior


    Path landmarks l.jpg

    PATH landmarks

    past across along

    LM

    LM

    LM


    Part whole schema l.jpg

    Part-Whole Schema

    Part

    Whole


    Representing image schemas l.jpg

    Representing image schemas

    semantic schemaSource-Path-Goal

    roles:

    source

    path

    goal

    trajector

    semantic schemaContainer

    roles:

    interior

    exterior

    portal

    boundary

    Boundary

    Interior

    Trajector

    Portal

    Source

    Goal

    Path

    Exterior

    These are abstractions over sensorimotor experiences.


    Language and spatial schemas l.jpg

    Language and Spatial Schemas

    • People say that they look up to some people, but look down on others because those we deem worthy of respect are somehow “above” us, and those we deem unworthy are somehow “beneath” us.

    • But why does respect run along a vertical axis (or any spatial axis, for that matter)? Much of our language is rich with such spatial talk.

    • Concrete actions such as a push or a lift clearly imply a vertical or horizontal motion, but so too can more abstract concepts.

    • Metaphors: Arguments can go “back and forth,” and hopes can get “too high.”


    Simulation based language understanding l.jpg

    constructionWALKED

    form

    selff.phon [wakt]

    meaning : Walk-Action

    constraints

    selfm.time before Context.speech-time

    selfm..aspect  encapsulated

    “Harry walked into the cafe.”

    Utterance

    Analysis Process

    Constructions

    General Knowledge

    Semantic

    Specification

    Belief State

    Simulation

    CAFE

    Simulation-based language understanding


    The i nto construction l.jpg

    The INTO construction

    constructionINTO

    subcase of spatial-prep

    form

    selff .phon  [Inthuw]

    meaning

    evokes Trajector-Landmark as tl

    evokes Container as cont

    evokes Source-Path-Goal as spg

    tl.trajector«spg.trajector

    tl.landmark«cont

    cont.interior«spg.goal

    cont.exterior«spg.source


    Simulation specification l.jpg

    Simulation specification

    • A simulation specification consists of:

    • schemas evoked by constructions

    • bindings between schemas


    Simulation based language understanding95 l.jpg

    constructionWALKED

    form

    selff.phon [wakt]

    meaning : Walk-Action

    constraints

    selfm.time before Context.speech-time

    selfm..aspect  encapsulated

    “Harry walked into the cafe.”

    Utterance

    Analysis Process

    Constructions

    General Knowledge

    Semantic

    Specification

    Belief State

    Simulation

    CAFE

    Simulation-based language understanding


    An experiment on image schemas l.jpg

    An experiment on Image Schemas

    • Richardson and Spivey (2003) operationalized this question by presenting participants with sentences and testing for spatial effects on concurrent perceptual tasks.

    • An interaction between linguistic and perceptual processing would support the idea that spatial representations are inherent to the conceptual representations derived from language comprehension (Barsalou, 1999).


    Example verbs l.jpg

    Example verbs

    The servant argued with the master.

    The storeowner increases the price.

    The girl hopes for a pony.

    The athlete succeeds at the tournament.

    The miner pushes the cart.


    Aspect angles l.jpg

    Aspect angles

    • Vertical was 90 and horizontal 0.

      • Mean aspect angles were

      • (12=H, 42=Neutral, 69=V)


    Example verbs101 l.jpg

    Example verbs

    Forced choice

    Free form

    The servant argued with the master. 20 11 H

    The storeowner increases the price. 85 75 V

    The girl hopes for a pony. 55 36 V

    The athlete succeeds at the tournament. 68 44V

    The miner pushes the cart. 10 12 H

    AVERAGE ASPECT ANGLE


    The experiment102 l.jpg

    The experiment

    • Each trial began with a central fixation cross presented for 1000 ms. A sentence was presented binaurally through headphones. There was then a pause of 50, 100, 150 or 200 ms.

      • This randomized “jitter” was introduced, so that participants could not anticipate the onset of the target visual stimulus.

    • The target, a black circle or square, then appeared in either the top, bottom, left or right position, and remained on screen for 200 ms.

    • Participants were instructed to identify the stimulus as quickly as possible, pressing one key to indicate a circle and another to indicate a square.

    • Reaction times and accuracy rates were recorded.

    • The questions were interrogative forms of the filler sentences with an object substitution in half of the cases (e.g., “Did the dog fetch the ball/stick?”). Participants responded “yes” or “no” by pressing designated keys.


    Summary of result l.jpg

    Summary of Result

    • There is an interference effect when the verb category is vertical (from norming study) and the visual stimulus object is vertical.

    • Issues with the experiment?


    Language and thought l.jpg

    Language and Thought

    Language

    • We know thought (our cognitive processes) constrains the way we learn and use language

    • Does language also influence thought?

    • Benjamin Whorf argues yes

    • Psycholinguistics experiments have shown that linguistics categories influence thinking even in non-linguistics task

    Thought

    cognitive processes


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