Prototype Theory Rosch (1976) has proposed an alternative to the view that concepts are com¬posed from sets of features which necessarily and sufficiently define instances of a concept. Rosch proposes that concepts are best viewed as prototypes: a ‘ bird’ is not best defined by reference to a set of features that refer to such matters as wings, warm-bloodedness, and egg-laying characteristics, but rather by reference to typical instances, so that a ‘ prototypical bird’ is something more like a robin than it is like a toucan, penguin, ostrich, or even eagle.

This is the theory of prototypes. As we saw in the preceding section, individuals do have ideas of typical instances of colors, and these ideas are remarkably similar among vari¬ous cultural groups. Such similarity in views, however, is found not only in reference to birds and colors.

A variety of experiments has shown that people do in fact classify quite consistently objects of various kinds according to what they regard as being typical instances; for example, (1) furniture, so that, whereas a chair is a typical item of furniture, an ashtray is not; (2) fruit, so that, whereas apples and plums are typical, coconuts and olives are not; and (3) clothing, so that, whereas coats and trousers are typical items, things like bracelets and purses are not (Clark and Clark, 1977, p. 64). The remarkably uniform behavior that people exhibit in such tasks cannot be accounted for by a theory which says that concepts are formed from sets of defining features. Such a theory fails to explain why some instances are consistently held to be more typical or central than others when all exhibit the same set of defining features. Hudson (1996, pp. 75-8) believes that prototype theory has much to offer sociolinguists.

He believes it leads to an easier account of how people learn to use language, particularly linguistic concepts, from the kinds of instances they come across. He says (p. 77) that: a prototype-based concept can be learned on the basis of a very small number of instances– perhaps a single one– and without any kind of formal definition, whereas a feature-based definition would be very much harder to learn since a much larger number of cases, plus a number of non-cases, would be needed before the learner could work out which features were necessary nd which were not. Moreover, such a view allows for a more flexible approach to understanding how people actually use language. In that usage certain concepts are necessarily ‘ fuzzy,’ as the theory predicts they will be, but that very fuzziness allows speakers to use language creatively. According to Hudson, prototype theory may even be applied to the social situations in which speech occurs.

He suggests that, when we hear a new lin¬guistic item, we associate with it who typically seems to use it and what, appar¬ently, is the typical occasion of its use. Again, we need very few instances — even possibly just a single one — to be able to do this. Of course, if the particular instance is atypical and we fail to recognize this fact, we could be in for some discomfort at a later time when we treat it as typical. Prototype theory, then, offers us a possible way of looking not only at how concepts may be formed, i. . , at the cognitive dimensions of linguistic behavior but also at how we achieve our social competence in the use of language. We judge circumstances as being typically this or typically that, and we place people in the same way. We then tailor our language to fit, making it appropriate to the situation and the participants as we view these. (Wardhaugh, Ronald. 1998. An Introduction to Sociolinguistics. 3rd ed. Blackwell Publishers Ltd. pp. 232-233. )