Prototype theory
Graded categorization

Linguists, including Stephen Laurence writing with Eric Margolis, have suggested problems with the prototype theory. In their 1999 paper, they raise several issues. One of which is that prototype theory does not intrinsically guarantee graded categorization. When subjects were asked to rank how well certain members exemplify the category, they rated some members above others. For example, robins were seen as being "birdier" than ostriches, but when asked whether these categories are "all-or-nothing" or have fuzzier boundaries, the subjects stated that they were defined, "all-or-nothing" categories. Laurence and Margolis concluded that "prototype structure has no implication for whether subjects represent a category as being graded" (p. 33).
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