chapter 9 - part 1
The more similar a specific exemplar is to a known category member, the faster it will be........
categorized
Prototypical category members are more affected by a......
priming stimulus
Barsalou & Sewell (1985): How typical are the following vehicles?
station wagon, minivan, sedan, tractor, pick-up truck. When asked to imagine what you drive if you're a farmer or soccer mom
Why are categories useful? 4 things*
- help to understand individual cases not previously encountered. "pointers to knowledge" -provide a wealth of general info about an item -allows us to identify the special characteristics of a particular item
Evidence that Basic-Level is Special
-Basic-level is much more common in adult discourse than names for superordinate categories -Different cultures tend to use the same basic-level categories, at least for living things
Evidence that Basic-Level is Special
-People almost exclusively use basic-level names in free-naming tasks -quicker to identify basic-level category member as a member of a category -Children learn basic-level concepts sooner than other levels
The Exemplar Approach takes into account and deals with....
-explaining the typicality effect -easily takes into account atypical cases -easily deals w/ variable categories
Rosch (1975) - color experiment
-hearing "green" primes a highly prototypical "green" -a dark green is more typical than light
which approach - prototypes or exemplars - provides a better description of how people use categories?
-may use both -exemplar work best for small categories -prototypes work best for larger categories
Categorization and Expertise: To fully understand how people categorize objects, one must consider....
-properties of objects -learning & experience of perceivers
According to the text, jumping from __________ categories results in the largest of info A. superordinate level to basic level B. basic to subordinate level C. subordinate level to basic level D. basic level to superordinate level
A
The prototype (typical) approach
An abstract representation of the typical member of a category -characteristic features that describe what members of that concept are like -An average of category members encountered in the past -contains most salient features that are true of most instances of that category
The Exemplar Approach
Concept is represented by multiple examples (rather than a single prototype) -examples are actual category members (not abstract averages) -to categorize, compare the new item to stored examples
2. Context Sensitivity Roth & Shoben (1983): Task
Context Given: The (sparrow/chicken) crossed the barnyard. No Context Given: no sentence given Then PS provided goodness-of-example ratings. How good of an example is (sparrow/chicken) of a bird?
Definitional Approach to Categorization
Determines category membership based on whether the object meets the definition of the category
The Definitional Approach to Categorization does not work well because *example
For example, the definition of a chair may sound reasonable, but there are objects that we can call "chairs" that don't meet rgra definition. ex: using a rock outside as a chair while you hike
The Definitional Approach to Categorization does not work well because
Not all members of everyday categories have the same defining features
Prototypical objects are named more rapidly meaning that
PS more likely to include "rose" than "hydrangea" in a naming or exemplar production task.
2. Context Sensitivity Roth & Shoben (1983): Result
Ratings were altered by prior context Context given: chicken > sparrow No context given: sparrow > chicken
The Exemplar Approach is different because....
Representation is not abstract. -descriptions of a specific examples
Problems for Prototype and Exemplar Theories 1. Atypical members and typical nonmembers: An electric eel is a fish, but a whale is not? An ostrich is a bird, but a bat is not?
Similarity would predict otherwise.
example of a category
The category for "cats" includes tabbies, siamese cats, persian cats, wildcats, leopards, and so on.
The prototype (typical) approach example
The prototype for the category "birds" might be based on some of the birds you usually see, such as sparrows, robins, blue jays, but doesn't necessarily look like any of them. thus, it is the "average" representation of the category.
Family resemblance
Wittgenstein proposed... Things in a category resemble one another in a # of ways.
exemplar
a member of the category
concept
a mental representation of a class of things
attribute
a predicate or property that can be true or false of a thing.
It may be that exemplars provide the basis for learning categories, but with experience.....
a prototype is formed, and later on, either prototypes or exemplars may be used
Although there are some critical differences between the Prototype theory and the Exemplar theory, they share important commonalities such as:
both theories claim that categorization is based on similarity
Concepts provide the rules for creating ________________ ?
categories
High-prototypically
category member closely resembles category prototype -"typical" member -for category bird = robin
Low-prototypically
category member does not closely resemble category prototype -for category bird = penguin
Family resemblance example
chairs may come in many different shapes and sizes and may be made of different materials, but every chair does resemble other chairs in some way.
A Hierarchical Organization see fig 9.8&9.9 global, basic & specific
different levels of categories, ranging from general like furniture to specific like kitchen table, and when people use categories, they tend to focus on one of these levels.
Strong positive relationship between prototypicality and __________ ___________
family resemblance
When items have a large amount of overlap with characteristics or other items in the category, the _____________ __________ of these items is high
family resemblance
Ad hoc categories (Barsalou, 1983): categories based on goals rather than similarity
for example: children, pets, important documents, expensive paintings, jewels, grandma category: things to remove from a burning house.
When there is a low overlap in characteristics, there is also a
low family resemblance
The Exemplar Approach is similar to....
prototype view. -representing a category is not defining it.
Ad hoc categories often appear to be created spontaneously for use in....
specialized contexts (ex: foods to eat while on a diet) -steeper graded structure
Medin & Shoben (1988): Typicality reversals Examples:
spoons are typically metal, but large spoons are typically plastic or wooden
example of a concept
the concept "cat" is the answer to the question "What is a cat?" -if your answer if that a cat is an animal that is furry, meows, moves and eats mice, you will have described that concept
category
the set of things included in the class -examples of a particular concept
Typical exemplars in terms of memory
they are more reliably recalled
The typicality effect & membership ratings states that
typical exemplars are judged to have greater membership
Production frequency (naming task) states that
typical exemplars are produced more frequently when asked to list exemplars in that category ex: for bird, sparrow would be named before penguin
Sentence verification times states that
typical exemplars are verified faster as belonging in the category ex: an apple is a fruit vs. a pomegranate is a fruit. Reaction time was faster for objects rated higher in prototypically
It is also likely that both theories can co-exist, meaning that.....
we can clearly have prototype for many concepts, and we clearly have exemplar for many concepts too
Instance-to-category association and category-to-instance association are less....
well-established in memory
