Abstract: | This work presents an analysis of a type of concept, the collection, not readily characterized by class inclusion models. Collections, the referents of collective nouns (e.g., pile, family, bunch), are argued to differ from classes in (a) how membership can be determined, (b) part-whole relationships, (c) internal structure, and (d) the nature of the higher order units they form. From this analysis, it is hypothesized that the psychological integrity of collections is greater than that of classes. Collections and objects, in contrast to classes, both require specified relationships among the parts and both result in a coherent psychological unit. It was suggested that objects form a relatively more stable unit than collections. Corresponding to this analysis the degree of psychological integrity is hypothesized to lead to different degrees of difficulty in making part-whole comparisons for objects, collections, and classes in modified Piagetian class-inclusion paradigms. The hypothesized difference in performance was found for collections and classes and an alternative linguistic explanation for the greater success with collections was eliminated. However, children performed equally well on tasks involving collections and objects, raising the possibility that when elements are organized into collections, they form psychological units which are as coherent as objects. |