Predicting conjunction typicalities by component typicalities

In two studies, we investigated to what extent typicalities in conjunctive concepts phrased as relative clauses-such as pets that are also birds-can b e predicted from simple functions of constituent typicalities and from exte nsions of such functions. In a first study, analyses of a large aggregated data set, based on seven different experiments, showed that a calibrated mi nimum rule model and some extensions of this model accounted for a very lar ge part of the variance in the conjunction typicalities. The same models ca n also account for the so-called guppy effect. A psychological explanation is presented, which states that typicalities in contrast categories, like p ets that are not birds and birds that are not pets, further improve the pre diction of conjunction typicalities. This hypothesis is tested in a second study.