 At the beginning of the 1970s, Eleanor Rosch put forth a new theory of the mental representation of categories. Concepts such as furniture or bird, she claimed, are not represented just as sets of criterial features with clear-cut boundaries, so that an item can be conceived as falling or not falling under the concept based on whether or not it meets the relevant criteria. Rather, items within categories can be considered more or less representative of the category itself (Rosch 1975; Rosch &amp; Mervis 1975; Mervis &amp; Rosch 1981). Several experiments seemed to show that the application of concepts is no simple yes-or-no business: some items (the “good examples”) are more easily identified as falling under a concept than others (the “poor examples”). An automobile is perceived as a better example of vehicle than a rowboat, and much better than an elevator; a carrot is more readily identified as an example of the concept vegetable than a pumpkin. If the concepts speakers associate to category words (such as ‘vehicle’ and ‘vegetable’) were mere bundles of criterial features, these preferences would be inexplicable, since they rank items that meet the criteria equally well. It is thus plausible to assume that the concepts associated to category words are have a center-periphery architecture centered on the most representative examples of the category: a robin is perceived as a more “birdish” bird than an ostrich or, as people would say, closer to the prototype of a bird or to the prototypical bird (see the entry on  concepts).