Re: Categorisation and Prototypes

From: Humphreys, Rebecca (
Date: Thu May 23 1996 - 12:36:01 BST

"What is the evidence for prototype theory of
category representation?"

According to the Prototype theory categories are organised around
central prototypes- the best example of the concept. Category
membership is determined by the simularity of an objects attributes to
the category's prototype. In contrast to the classical view of
categorisation where features are necessary and sufficient for deciding
what belongs in what category. Rosch gave evidence for the theory
saying whilst a categories defining attributes existed people could
often not define them. Some may have features impossible to define i.e
"game" the only thing it's members have in common are vague "family
resemblances" not features (Wittgenstein). They could however name more
"typical" members of categories i.e Robin is a more typical example of
a bird than Ostrich, and faster than the more obscure. Berlin and Kay's
(1969) crosscultural studies showed a universality in people's colour
ctaegorisation. People could agree on the best example of red or blue,
and seemed to categorise colours on the basis of resemblance to focal
colours. The prototype theory requires a template of an idealised
member of categories, but not all concepts have prototype
characteristics i.e what is the "ideal" chair. The prototype of which
is a set of features not an "ideal" member. Prototypes do not explain
how people know some attributes of a categegory are more likely to vary
than others. Simularity cannot be the only mechanism responsible for
category cohesion- some categories are coherent but don't share many
attributes. People may not be able to tell you what the features of a
category are but may know implicitly. The prototype approach has not
led to a model being built that can categorise, whereas the classical
view has had some success in modelling in human categorisation. The

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