Continuity and the persistence of objects: when the whole is greater than the sum of the parts.

In three experiments, a total of 480 participants heard a version of the story of the ship of Theseus (Hobbes, 1672/1913), in which a novel object, labeled with a possessive noun phrase, underwent a transformation in which its parts were replaced one at a time. Participants then had to decide which of two objects carried the same possessive noun phrase as the original: the one made entirely of new parts (that could be inferred to be continuous with the original) or one reassembled from the original parts (that could not be inferred to be continuous with the original). Participants often selected the object made of new parts, despite the radical transformation. However, the tendency to do so was significantly stronger (1) if the object was described as an animal than if it was described as an artifact, (2) if the animal's transformation lacked a human cause than if it possessed one, and (3) if the selection was made by adults or 7-year-olds than if it was made by 5-year-olds. The findings suggest that knowledge about specific kinds of objects and their canonical transformations exerts an increasingly powerful effect, over the course of development, upon people's tendency to rely on continuity as a criterion for attributing persistence to objects that undergo change. Copyright 1998 Academic Press.