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guppy effect

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An anomaly in prototype theory, in which an item is more prototypical of a conjunctive concept than of either (or any) of its constituent concepts. Thus a guppy is supposedly more prototypical of the conjunctive concept pet fish than of either of the constituent concepts pet or fish, and if prototype theory is formulated in the theory of fuzzy sets, this leads to a contradiction, implying that either the apparently natural formulation in the theory of fuzzy sets, or prototype theory itself, must be fundamentally flawed. The concept of goldfish has also been claimed to manifest the guppy effect, because it is a more prototypical instance of a pet fish than of a pet or a fish, and empirical research has uncovered many other examples, such as atlas, more prototypical of reference books than of reference sources or books. The anomaly was first uncovered and the example of the guppy suggested in 1981 by the US psychologists Daniel N. Osherson (born 1949) and Edward E. Smith (born 1940).

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