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Prototype theory is a mode of graded categorization in cognitive science, where some members of a category are more central than others. For example, when asked to give an example of the concept ''furniture'', ''chair'' is more frequently cited than, say, ''stool''. Prototype theory has also been applied in linguistics, as part of the mapping from phonological structure to semantics. As formulated in the 1970s by Eleanor Rosch and others, prototype theory was a radical departure from traditional necessary and sufficient conditions as in Aristotelian logic, which led to set-theoretic approaches of extensional or intensional semantics. Thus instead of a definition based model - e.g. a bird may be defined as elements with the features (), () and (to fly ), prototype theory would consider a category like bird as consisting of different elements which have unequal status - e.g. a ''robin'' is more prototypical of a ''bird'' than, say a ''penguin''. This leads to a graded notion of categories, which is a central notion in many models of cognitive science and cognitive semantics, e.g. in the work of George Lakoff (''Women, Fire and Dangerous Things'', 1987) or Ronald Langacker (''Foundations of Cognitive Grammar'', vol. 1/2 1987/1991). The term prototype has been defined in Eleanor Rosch's study "Natural Categories" (1973) and was first defined as a stimulus, which takes a salient position in the formation of a category as it is the first stimulus to be associated with that category. Later, she redefined it as the most central member of a category. ==Categories== In her 1975 paper, ''Cognitive Representation of Semantic Categories'' (J Experimental Psychology v. 104:192-233), Eleanor Rosch asked 200 American college students to rate, on a scale of 1 to 7, whether they regarded the following items as a good example of the category ''furniture''. This ranged from chair and sofa, ranked number 1, to a love seat (number 10), to a lamp (number 31), all the way to a telephone, ranked number 60. While one may differ from this list in terms of cultural specifics, the point is that such a graded categorization is likely to be present in all cultures. Further evidence that some members of a category are more privileged than others came from experiments involving: :1. ''Response Times'': in which queries involving a prototypical members (e.g. ''is a robin a bird'') elicited faster response times than for non-prototypical members. :2. ''Priming'': When primed with the higher-level (superordinate) category, subjects were faster in identifying if two words are the same. Thus, after flashing ''furniture'', the equivalence of ''chair-chair'' is detected more rapidly than ''stove-stove''. :3. ''Exemplars'': When asked to name a few exemplars, the more prototypical items came up more frequently. Subsequent to Rosch's work, prototype effects have been investigated widely in areas such as colour cognition (Brent Berlin and Paul Kay, 1969), and also for more abstract notions. Subjects may be asked, e.g. "to what degree is this narrative an instance of telling a lie?" (). Similarly work has been done on actions (verbs like look, kill, speak, walk ()), adjectives like "tall" (), etc. Another aspect in which Prototype Theory departs from traditional Aristotelian categorization is that there do not appear to be natural kind categories (bird, dog) vs. artifacts (toys, vehicles). A common comparison is the use of prototype or the use of exemplars in category classification. Medin, Altom, and Murphy (1984) found that using a mixture of prototype and exemplar information, participants were more accurately able to judge categories. Participants who were presented with prototype values classified based on similarity to stored prototypes and stored exemplars, whereas participants who only had experience with exemplar only relied on the similarity to stored exemplars. Smith and Minda (2002) looked at the use of prototypes and exemplars in dot-pattern category learning. They found that participants used more prototypes than they used exemplars, with the prototypes being the center of the category, and exemplars surrounding it. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prototype theory」の詳細全文を読む スポンサード リンク
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