Schemas Scripts and Mental Models

Mental Representations: The Ingredients of Thought
251
YOU CAN’T JUDGE A BOOK BY ITS
COVER Does this person look like a
millionaire to you? Our schemas tell us
what to expect about objects, places,
events, and people, but those expectations can sometimes be wrong. This was
dramatically illustrated in October 1999
when Gordon Elwood died. The Medford,
Oregon, man, who dressed in rags and
collected cans, left over $9 million to
charity (McMahon, 2000).
not enough, though. A snake lays eggs and a bat can fly, but neither animal is a bird.
It is usually a combination of properties that defines a concept. In most situations outside the laboratory, people are thinking about natural rather than formal concepts.
These natural concepts include object categories, such as “bird” or “house.” They also
include abstract idea categories, such as “honesty” or “justice,” and goal-related categories, such as “things to pack for my vacation” (Barsalou, 1993).
The boundaries of a natural concept are fuzzy, so some members are better examples
of it than others. A robin, a chicken, an ostrich, and a penguin are all birds. But the robin
is a better example of the bird concept than the others, because it is closer to what most
people have learned to think of as a typical bird. A member of a natural concept that possesses all or most of its characteristic features is called a prototype. The robin is a prototypical bird. The more prototypical of a concept something is, the more quickly you can
decide whether it is an example of the concept. This is the reason people can answer just
a little more quickly when asked “Is a robin a bird?” than when asked “Is a penguin a bird?”
Propositions
prototype A member of a natural concept that possesses all or most of its
characteristic features.
propositions Mental representations
that express a relationship between
concepts
schemas Generalizations about
categories of objects, places, events,
and people.
We often combine concepts in units known as propositions. A proposition is a mental
representation that expresses a relationship between concepts. Propositions can be true
or false. Suppose you hear someone say that your friend Heather broke up with her
boyfriend, Jason. Your mental representation of this event will include a proposition that
links your concepts of “Heather” and “Jason” in a particular way. This proposition could
be diagrammed (using unscientific terms) as follows: Heather → dumped → Jason.
The diagram looks like a sentence, but it isn’t one. Propositions can be expressed as
sentences, but they are actually general ideas that can be conveyed in any number of
specific ways. In this case, the words “Jason was dumped by Heather” and “Heather is
not willing to date Jason anymore” would all express the same proposition. If you later
discovered that it was Jason who caused the breakup, the diagram of your proposition
about the event would change to reflect this new information, shown here as reversed
arrows: Heather ← dumped ← Jason.
Schemas, Scripts, and Mental Models
Sets of propositions are often so closely associated that they form more complex mental
representations called schemas. As mentioned in the chapters on sensation and perception,
memory, and human development, schemas are generalizations that we develop about
categories of objects, places, events, and people. Our schemas help us to understand the