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Ch. 8: Categories and concepts. Concept and Knowledge. Topic: How do we store and manipulate a concept in the brain?. Concepts, beliefs and behavior. Concept/belief and action. Mother Teresa Timothy McVeigh (Oklahoma bomber) Ted Kaczynski (the unabomber) Osama bin Laden Mahatma Gandhi

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concept and knowledge
Concept and Knowledge
  • Topic:
    • How do we store and manipulate a concept in the brain?
concept belief and action
Concept/belief and action
  • Mother Teresa
  • Timothy McVeigh (Oklahoma bomber)
  • Ted Kaczynski (the unabomber)
  • Osama bin Laden
  • Mahatma Gandhi
  • Nelson Mandela
  • George Washington
  • 74 men and women died in Waco, TX
  • Bill Clinton
psychiatric disorders
Psychiatric disorders
  • Anxiety disorder
    • Is created by an lingering belief on something threatening happens
  • Maniac depression
    • Disbelief on one’s ability, fate, etc.

Political language:

  • Compassionate conservative
      • support the rich but also, supposedly, generous to the poor.
  • Limousine liberal
      • extremely rich but appreciate liberal ideas.
  • War president
      • A president who deals with war.
  • Death tax
      • Inheritance tax
  • Pro-life
      • a political position against abortion
  • Pro-choice
      • a political position that supports abortion
  • Insurance premium
      • Insurance fee
  • Tax cuts
      • cutting taxes of one group and raising taxes for others
  • Ethnic conflicts
concept and memory
Concept and memory?
  • Are they two different things?
what is the structure of concept
What is the structure of “concept”?

This is the today’s topic.

  • Tell me what you see as accurately as possible.
why do you say hammer
Why do you say “hammer”?
  • Why not “hand tool”?
  • Or why not the $15 hammer I bought in Wal Mart last Wednesday?
  • Why not “animal”?
  • Or why not “vegetable”?
what is concept
What is “concept”?
  • I don’t know
    • But maybe concept we have is related to the way we categorize things
concept categories
Concept --> categories
  • In order to study “concept”, I’ll talk about “categories” .
there are trillions of categories
There are trillions of categories.
  • Animals, dogs, cats, birds, mammals, furniture, desks, chairs, tables, books, magazines…..
  • Trees, grass, weed, stones, rocks, sand, mountains, rivers,…..
  • Games, sports, hobbies, …
  • school, banks, shops, restaurants, supermarkets,
Nazi!! Fascists!! Terrorists, racists, sexists, pacifists, philanthropists, sophists, aristocrats, workers, bankers, lawyers, accountants, teachers, students, disciples, masters, gurus, beggars, bigots,
  • Party animals, beasts!!, dogs!!,
  • CEO, CFO, CIO, UFO, evp, vip,
  • IC (Indian Chief)
ad hoc categories
Ad hoc categories
  • People I adore, People I admire, People I hang around, People I need, People I avoid.
  • Things I love, Things I enjoy, Places I love, Food I hate, music I like, movies I enjoy
  • countries I want to visit, restaurants I avoid
when we say dog what s going on in our mind
When we say “dog,” what’s going on in our mind?
  • What is the mental representation of “categories”?
  • How do we distinguish in our mind
    • a dog from a cat?
    • a circle from a triangle?
  • What’s going on?
    • What is the structure?
    • What is the neural connections?
  • What determines “dog” vs. “cat” or “table” vs. “vegetable”, “game” vs. “sport”,…..
classical view
Classical view
  • Necessary & sufficient rule
    • we store definitions.
  • Circle --> an area circumscribed by an equidistant curve.
  • Triangles --> an area circumscribed by three straight lines having three angles………..

A circle of friends, Dupon circle, Columbus Circle, Circle line

Bermuda triangles, triangle defense (Chicago Bulls)

Brother, sister, mother, father, uncle,
  • Some concepts may be organized with specific rules.
  • But how about other categories?
    • Game?
      • Basketball, softball, horse race, chess, a wheel of fortune, survivor, roulette, love affair, computer game, Super Mario?
    • furniture
      • desk, table, rug? Bed? Computer? TV?
concepts and categories
Concepts and categories
  • Pink is basically red.
  • 99 is almost 100.
  • Orange is sort of yellow.
  • Austin is like Rome.
  • San Antonio is very much like Mexico.
  • Pita can be bread.
concepts and categories ii
Concepts and categories II
  • Red is basically pink.
  • 100 is almost 99.
  • Yellow is almost orange.
  • Rome is like Austin.
  • Mexico is very much like San Antonio.
  • Bread can be pita.
which game is the best example of game
Which game is the best example of “game”?
  • Baseball
  • Chess
  • Basketball
  • Politics
  • Football
  • Golf
  • One-night love affair
  • Snowboarding
  • Checker
  • Ping-Pong
  • Slot machine
  • Poker
  • Mahjong
  • Horse racing
  • NASCAR racing
fruit vs vegetable
Fruit vs. Vegetable







Bitter Melon
















Grape fruit






  • Fruits  banana
    • Sweet, can eat without cooking, lots of vitamin, from tropical countries, soft, ripe quickly, easy to eat, kids love it, tasty, can bring it for hiking
  • Vegetables  carrot
    • Not sweet, not tasty, require some cooking, lots of vitamin, from anywhere, hard, stay long, kids don’t like it, hard
probabilistic view
Probabilistic view
  • The boundaries of categories are fuzzy (probabilistically determined).
  • Some members are more probable than others.
  • But we are pretty sure about what “dog” means.
  • How do we mentally represent categorical knowledge?
organization of categories
Organization of categories
  • Members of categories are organized in relation to some focal members. (prototype)
  • Focal members play the role of a “reference point.”
  • The boundaries of categories may be fuzzy, but people know pretty well which items are “good/bad” members of a category.
    • Penguin vs. robin, chair vs. rug,
measuring goodness of category members
Measuring “goodness” of category members
  • Rosch et al. (1975)
  • Experiments:
  • Subjects were given a list containing the names of category members.
  • Subjects rated (using a 1-10 scale) the goodness of membership.
    • E.g., given “pistol”, subjects rated how good a pistol is as a member of the category “weapons.”
Furniture (chair, lamp, rug, dresser, desk, stove, table, stool, television, fan, bed, television, counter)
  • Fruit (apple, grapefruit, watermelon, banana, cherries, boysenberry, pear, strawberries, lemon, orange, pineapple, nut)
  • Vehicle (car, airplane, sled, bus, bicycle, wheelchair, truck, boat, tractor, ambulance, trolley, wagon).
  • Weapon (pistol, arrow, slingshot, sword, tomahawk, whip, knife, cannon, fist, rifle, club, bow)
  • Vegetable (peas, celery, mushrooms, corn, turnips, potatoes, carrots, tomatoes, green onions, green beans, artichoke, pumpkin)….
  • Other categories, bird, sport, toy, clothing.
    • Correlations: 0.95 or up (=1 is perfect correlation)
    • People agree very much which items are good/bad examples of a particular category.
    • Categories have “good” examples and “bad” examples.
    • The boundaries of categories are graded, and may be arranged probabilistically with “goodness” of membership.
  • What determine “goodness”? Or what makes a particular item a good example of a category?
typicality and feature distribution
Typicality and feature distribution
  • What makes an item a typical member of a category.
  • How do we perceive a particular item a typical member of a given category?
family resemblance rosch mervis 1975
Family resemblance Rosch & Mervis (1975)
  • Distribution of attributes (features)
    • The most typical item in a category has the most features in common with other members of a category,
    • and the fewest features in common with the member of contrasting categories.
  • These items are ideal examples and may be referred to as “prototype.”












  • Morphed images of two different human faces

( Angelina Jolie – Brad Pitt by Na Yung Yu)

vertical structure of categories
Vertical structure of categories
  • Why “dog” rather than “animal”?
  • Categories have a vertical structure.
  • Not all levels of categories are created equal.
    • One intermediate level of categories, which is called, basic level categories, plays a crucial role in our perceptual and cognitive operations
rosch et al 1978
Rosch et al. (1978)
  • Basic (intermediate) level categories
    • Most efficient in identification
    • Evokes specific visual representations
    • People use this level exclusively for naming
    • Kids tend to learn these names earlier than other levels of categories
exp 1
Exp. 1
  • Speed of classification
  • Shown a category name (animal -upper level, dog-intermediate level, or German shepherd low level) followed by a picture.
  • Subjects responded whether the category name matched with the picture (pressing a either yes or no key)



Polar bear

Results :

Basic level items are the easiest to classify

basic level categories and representation
Basic level categories and representation
  • Basic level categories evoke specific visual representations.
    • Given “furniture”, what kind of representation do you have in your mind?
    • How about “desk”?
  • Basic level category names evokes a specific pictorial representation
rosh et al 1978
Rosh et al. (1978)
  • Object matching task and priming
  • Object matching task
    • Two pictures were shown on a screen briefly side by side.
    • Subjects’ task was to indicate whether or not the two pictures depicted identical objects
2 conditions
2 conditions
  • Primed trials
    • 2 seconds before the presentation of picture pairs, the category name of one of the pair was presented.
  • Non primed trials
    • No names were given prior to the trials.
  • Dependent measure
    • Accuracy and response time
procedure primed condition
Procedure (primed condition)

Animal / cat / Persian cat

Depending on trials, upper (animal), basic (intermediate), or low level (Persian cat) category names appeared.


15 subjects  primed with upper level names (animal)
  • 15 subjects  primed with basic level names (dog)
  • 15 subjects  low level names (German shepherd)
  • All the subjects were also given non-primed trials.

RT for “Same”

Priming conditions



Basic level name (cat)

Subordinate (kitten)













  • Given the name of a basic level category, people form a specific pictorial representation.
categories concept
  • Categories have a structure.
    • Horizontal structure
      • Distinction between dogs vs. Cats.
      • Prototype, family resemblance
        • The most typical item in a category has the most features in common with other members of a category,
        • and the fewest features in common with the member of contrasting categories.
    • Vertical structure
      • (Animal, mammal, dog, German Shepherd)
      • The mid-level categories that we used for naming are called “basic level” categories.
      • Basic level categories have cognitive and perceptual significance.