: DEFINING-ATTRIBUTE
THEORIES OF CONCEPTS
• The meaning of a concept can be
captured by a conjunctive list of attributes (i.e., a list of attributes connected by ANDs).
• These attributes are atomic
units or primitives which are the basic building blocks of concepts.
• Each of these attributes is
necessary and all of them are jointly sufficient for something to be identified as an instance of the
concept.
• What is and is not a member of
the category is clearly defined; thus, there are clear-cut boundaries between members and
non-members of the category.
• All members of the concept are
equally representative.
• When concepts are organised in
a hierarchy then the defining attributes of a more specific concept (e.g., sparrow) in
relation to its more general relative (Its superordinate; e.g., bird) includes all the defining attributes of the
superordinate.
: CONCEPT HIERARCHIES
• People use hierarchies to
represent relationships of class inclusion between categories; that is, to include one category within
another (e.g., the category of chair within the category for furniture).
• Human conceptual
hierarchies have three levels;
a
superordinate level (e.g., weapons, furniture),
a
basic level
(e.g., guns, chair),
a
subordinate level of specific concepts (hand-guns, rifles, kitchen
chairs, armchairs).
• The basic level is the level at
which concepts have the most
“distinctive attributes” and it is the most cognitively economic; it is the level at which a concept’s attributes are not shared with other concepts at that level.
“distinctive attributes” and it is the most cognitively economic; it is the level at which a concept’s attributes are not shared with other concepts at that level.
• Categories at the basic level
are critical to many cognitive activities; for example, they contain concepts that can be interacted with using similar motor movements, they have the same general shape, and they may be associated
with a mental image that represents the whole category.
• The position of the basic level
can change as a function of individual differences in expertise and cultural differences.
A schematic diagram of the sort of hierarchical,
semantic networks proposed by Collins and Quillian (1969)
PROTOTYPE THEORY OF
CONCEPTS
• Concepts have a prototype
structure; the prototype is either a collection of characteristic attributes or the best example
(or examples) of the concept.
• There is no delimiting set of
necessary and sufficient attributes for determining category membership; there may be
necessary attributes, but they are not jointly sufficient; indeed membership often depends on the
object possessing some set of characteristic, non-necessary attributes that are considered
more typical or representative of the category than others.
• Category boundaries are fuzzy
or unclear; what is and is not a member of the category is illdefined; so some members of the category
may slip into other categories (e.g., tomatoes as fruit
or vegetables).
• Instances of a concept can be
ranged in terms of their typicality; that is, there is a typicality gradient which characterises the differential typicality of examples of the concept.
• Category membership is
determined by the similarity of an object’s attributes to the category’s prototype.
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