Instance-of-object-kind representations.

We naturally think and talk about the objects we encounter as instances of one or another kind of object (e.g. as a dog). This paper makes a proposal concerning the instance-of-object-kind representations that allow us to think of things as instances of object kinds and investigates two predictions of the proposed representations. Instance-of-object-kind representations represent an object as one of indefinitely many instances of a given object kind. In so doing, they implicate a uniqueness-in-kind constraint which represents an object as unique within a kind, by distinguishing the instance-of-object-kind representation of an object from instance-of-object-kind representations of other actually as well as potentially existing instances of that object kind. The uniqueness-in-kind constraint predicts that a given instance of an object kind cannot be transformed into a different potentially existing instance of the same kind, but allows the object to be transformed into a potentially existing instance of a different object kind. Instance-of-object-kind representations also implicate a mode-of-existence constraint whereby actually existing instances of an object kind are represented as being distinct from all actually existing instances of that kind and other object kinds. This constraint predicts that participants should reject the possibility of transforming an actually existing instance of an object kind into an actually existing instance of the same or different object kind. Five experiments provide evidence for these constraints. In so doing, the experiments provide evidence for the formal characteristics of the proposed instance-of-object-kind representations that guide our thinking about things as instances of object kinds.