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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

Categories and concepts- introduction

CS182/Ling109/CogSci110

Spring 2007

lecture outline
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
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
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
Concepts
  • What Concepts Are: Basic Constraints
    • Concepts are the elements of reason, and
    • constitute the meanings of words and linguistic expressions.
slide6

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
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
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.
classical vs prototype model of categorization
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
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
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
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
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
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
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.
slide17
chair desk chair

easy chair rocking chair

furniture lamp desk lamp

floor lamp

table dining room table coffee table

Superordinate Basic Subordinate

categories prototypes overview
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
Basic-level -- Criteria
  • Perception –
    • overall perceived shape
    • single mental image
    • fast identification
basic level criteria20
Basic-level -- Criteria
  • Perception
  • Function – motor program for interaction
basic level criteria21
Basic-level -- Criteria
  • Perception
  • Function
  • Words –
    • shortest
    • first learned by children
    • first to enter lexicon
basic level criteria22
Basic-level -- Criteria
  • Perception
  • Function
  • Communication
  • Knowledge organization –
    • most attributes are stored at this level
basic level category
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
Other Basic-level categories
  • Objects
  • Colors
  • Motor-routines
mother
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
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
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
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
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
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
Neural Evidence for category structure
  • Are there specific regions in the brain to recognize/reason with specific categories?
category naming and deficits
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)
study
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
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
conclusions
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
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
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
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)
the experiment45
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
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
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).

neural evidence for category structure51
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
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
Basis of Image schemas
  • Perceptual systems
  • Motor routines
  • Social Cognition
  • Image Schema properties depend on
    • Neural circuits
    • Interactions with the world
image schemas

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
Similarity:
  • Perceptual and motor systems
  • Basic functional interactions with the world
  • Environment

Variation:

Cross-linguistic variation in how schemas are used.

english59

AROUND

ON

IN

OVER

English

Bowerman & Pederson

dutch

OP

OM

AAN

IN

BOVEN

Dutch

Bowerman & Pederson

chinese

ZHOU

LI

SHANG

Chinese

Bowerman & Pederson

spatial schemas
Spatial schemas
  • TR/LM relation
  • Boundaries, bounded region
  • Topological relations
  • Orientational Axes
  • Proximal/Distal
trajector landmark schema
Trajector/Landmark Schema
  • Roles:

Trajector (TR) – object being located

Landmark (LM) – reference object

TR and LM may share a location (at)

tr lm asymmetry
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
Boundary Schema

Roles:

Boundary

Region A

Region B

Region A

Region B

Boundary

bounded region
Bounded Region

Roles:

Boundary: closed

Bounded Region

Background region

topological relations68
Topological Relations
  • Separation
  • Contact
topological relations69
Topological Relations
  • Separation
  • Contact
  • Coincidence:
topological relations70
Topological Relations
  • Separation
  • Contact
  • Coincidence:

- Overlap

topological relations71
Topological Relations
  • Separation
  • Contact
  • Coincidence:
    • Overlap
    • Inclusion
topological relations72
Topological Relations
  • Separation
  • Contact
  • Coincidence:
    • Overlap
    • Inclusion
  • Encircle/surround
orientation
Orientation
  • Vertical axis -- up/down

up

above

upright

below

down

orientation74
Orientation

Horizontal plane – Two axes:

language and frames of reference
Language and Frames of Reference
  • There seem to be three prototypical frames of reference in language (Levinson)
    • Intrinsic
    • Relative
    • Absolute
relative frame of reference
Relative frame of reference

right??

back

front

left??

absolute frame of reference
Absolute frame of reference

west

south

north

east

tr lm and verticality schemas
TR/LM and Verticality Schemas
  • The book is under the table.

up

down

under

container schema
Container Schema
  • Roles:
    • Interior: bounded region
    • Exterior
    • Boundary

C

container schema elaborated
Container Schema Elaborated
  • Complexities –more roles/specifications:
    • Boundary properties
      • Strength
      • Porosity
    • Portals
source path goal
Source-Path-Goal

Constraints:

initial = TR at Source

central = TR on Path

final = TR at Goal

Source

Path

Goal

spg simple example
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
SPG and Container

She ran into the room.

SPG. Source ↔ Container.Exterior

SPG.Path ↔ Container.Portal

SPG. Goal ↔ Container.Interior

path landmarks
PATH landmarks

past across along

LM

LM

LM

representing image schemas
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
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

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
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
Simulation specification
  • A simulation specification consists of:
  • schemas evoked by constructions
  • bindings between schemas
simulation based language understanding95

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
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
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
Aspect angles
  • Vertical was 90 and horizontal 0.
    • Mean aspect angles were
    • (12=H, 42=Neutral, 69=V)
example verbs101
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
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
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
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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