Concepts, Categories and Generic Knowledge 10/23/2013 9:32:00 AM
The building blog of our knowledge
Ex. The concept of a dog, concept of a birthday party
Concepts are more generic than memory – not tied to a specific
Generic memories are things you know without specifically knowing
where you know them from
Including stuff you never even thought of as “knowing”
o Including schemata: what is in a professor’s office, what you
do at a restaurant
What does it mean to know what a “dog” is? How do we know that
something belongs to the category “dog”?
o Concepts and cats aren’t the same thing as words. We use
words to describe cats, but they are not exactly the same.
o Eg. Big, huge, large
o You have al kind of concepts that you don’t have a word for,
and some concepts you have many words for
o Ex. Between your nose and mouth – you know what it is, the
concept, may not know it’s a Philtrum
Concept: a mental representation
Ex. See what a dog is.
Category: the set of entities or examples picked out by the concept
Ex. All the dogs in the world.
We are prone to putting things into bins (categorizing)
Enables us to make sense of the world – use our previous
experience and profit from it
If you couldn’t categorize, every instance would be a new category,
and knowledge would never help you make any useful predictions
about it’s properties
Functions of Concepts
Concepts allow us to treat two different things as equivalent Deciding that two or more things belong to the same category (pug
and Doberman are dogs
Allows us to break experience apart into meaningful chunks, and to
construct an interpretation of it; allows us to bring old knowledge to
bear on new situations
ex. Understanding the “Jane” story
We understand the story because of our concept of children, piggy
Classification allows us to make predictions about the future so we
can select plans and actions
Ex. On a cloudy day you may want to bring an umbrella
You don’t need to store every fact if inferences can be derived from
information that is stored
Ex. Kangaroos breathe, ducks breathe, pigs breathe ANIMALS
Using the same categories allows us to communicate knowledge to
Ex. Don’t need to explain a dog as a furry little four-legged animal
Ex. Someone not having a concept makes it hard to have a
How do we do this? How do we categorize millions of little
things/actions/attributes/experiences that we know about?
What do we base our categories on? Is the world naturally divided into
categories, or do our categories help us function in the world?
Classical View Concepts have defining features
Ex. What is a dog? Define it’s features. Four-legged, furry,
What about a dog that doesn’t bark? A dog that doesn’t have four
legs? How can we classify without the categories? There are usually
Hard to come up with a good def. maybe there is a good one
(something to do with DNA maybe?), we just haven’t come up with
Ex. Def. of a bachelor?
Even without definitions, we still have concepts
We still know what a dog is, without having to undertake his DNA.
Psychologists reject the classical view.
Category member have a family resemblance to each other – some
features in common, but not every member has to have those
features. Different members have different features in common.
Ex. No one think that defines all 7 dwarves.
Definition becomes PROBABILISTIC
If you have X and Y, it is likely that you belong to category T.
THIS MEANS: No necessary conditions for belonging to a category,
no sufficient definitions either.
Does not take structure away from category – still things in
common, but things in common will change depending on case
Fuzzy boundaries – there are degrees of “dogness”, some dogs are
better examples of dogs than others.
The AVERAGE of a category – what is an “ideal” dog
Things that are more similar to prototype are good dogs; as they
get more and more dissimilar, they are less and less good dogs,
and eventually, not dogs at all Graded membership
Ex. Golden retriever may be in the centre – most like dogs around,
most different, less likely to be a “dog” according to concept Not most frequent, often the best.
Ex. Drawing a tree – you’d probably draw big one with full leaves, it
is not the actual more frequent/average one you encounter
Ex. People would rate morphed face of average-ness as most
Sentence verification: is this true or not?
Ex. Is a robin a bird? Is an emu a bird?
Measure reaction time – faster reaction, more typical example
Ex. Rank “sofa, dining room table, ottoman, piano, TV stand” as to
how TYPICAL of category furniture
There would be high ratings of dining room table compared to piano
for “typical furniture”
Different people may have different prototypes (different “ideals”) –
based on personal experience
Ex. Protypical fruit for Jamaica is different than Canada
Basic Level Categories
Superordinate – vehicle
Subordinate – 2001 Honda civic
We usually describe the world in terms of basic level categories
Languages usually have one word for basic level categories
E.g. “chair”, “apple”, vs. “rocking chair”, “granny Smith apple”
Children learn basic level