On prototypes as defaults (Comment on Connolly, Fodor, Gleitman and Gleitman, 2007)

In an interesting contribution to research on conceptual combination, Connolly, Fodor, Gleitman, and Gleitman (2007) (CFGG) tested a hypothesis that they identified as a common assumption of prototype models of conceptual combination, ‘the crucial default to the stereotype prediction’ (DS). Defaulting to the stereotype consists in assuming, barring information to the contrary, that the prototype corresponding to an adjective noun combination (AN), fully inherits the properties of the prototype corresponding to the noun (N) of that combination. For instance, the prototype corresponding to uncomfortable sofa should share all the properties of the sofa prototype, except for those properties that have to do with comfort. In contradiction of this hypothesis, they reported an experiment in which people’s willingness to accept that a property is true of the members of some class tended to be lower when the concept was modified (uncomfortable sofas have backrests) than when it was unmodified (sofas have backrests). According to CFGG, since all prototype models of conceptual combination require DS to be true, the empirical demonstration that DS fails should be taken as important evidence against the correctness of such models.