Ch. 8: Categories and concepts

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Ch. 8 Categories and concepts
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Concept and Knowledge

• Topic
• How do we store and manipulate a concept in the
  brain?

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Concepts, beliefs and behavior
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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

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Psychiatric disorders

• Anxiety disorder
• Is created by an lingering belief on something
  threatening happens
• Maniac depression
• Disbelief on ones ability, fate, etc.

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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

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Stereotype

• Ethnic conflicts

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Concept and memory?

• Are they two different things?

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What is the structure of concept?
This is the todays topic.
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Demonstration

• Tell me what you see as accurately as possible.

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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?

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What is concept?

• I dont know
• But maybe concept we have is related to the way
  we categorize things

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Concept --gt categories

• In order to study concept, Ill talk about
  categories .

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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,

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• 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)

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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

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• Circles, triangles, squares, dots, lines,
  rectangles, plane,
• 1, 2, 3, 4, 100, 120,
• A, B, C, D,..

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The format of representing a category
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When we say dog, whats 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?
• Whats going on?
• What is the structure?
• What is the neural connections?

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Which woman looks more attractive/friendly/pleasan
t/capable?
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Concepts

• What determines dog vs. cat or table vs.
  vegetable, game vs. sport,..

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Classical view

• Necessary sufficient rule
• we store definitions.

Circle --gt an area circumscribed by an
equidistant curve. Triangles --gt 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)
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• 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?

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Alternative view
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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.

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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.

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Birds which one looks more like bird?
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Which desk is the best example of desk?
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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

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Fruit vs. Vegetable

• Onion
• Carrot
• Pepper
• Potato
• Jalapeno
• Cucumber
• Bitter Melon
• Spinach
• Garlic
• Ginger
• Broccoli
• Plantain
• Lettuce
• Cabbage
• Pumpkin

• Banana
• Apple
• Melon
• Grapes
• Lemon
• Avocado
• Orange
• Grape fruit
• Kiwi
• Papaya
• Mango
• Lime
• Tomato

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Example

• 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
  dont like it, hard

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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?

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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,

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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.

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• 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.

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Results

• 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?

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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?

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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.

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Which woman looks more attractive/friendly/pleasan
t/capable?
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Which woman looks more attractive/friendly/pleasan
t/capable?
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Who is he/she?
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• Morphed images of two different human faces
• ( Angelina Jolie Brad Pitt by Na Yung Yu)

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By Na Yung Yu
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By me
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Just averaging the two faces
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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

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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

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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)

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Bear
Animal
Polar bear
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Results
Basic level items are the easiest to classify
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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

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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

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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

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Procedure (primed condition)
Animal / cat / Persian cat
Depending on trials, upper (animal), basic
(intermediate), or low level (Persian cat)
category names appeared.
Yes/no
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• 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.

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• animal

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mammal
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• cat

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• kitten

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Results
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Interpretation

• Given the name of a basic level category, people
  form a specific pictorial representation.

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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.