The Development of Kind Concepts: Insights From Object Individuation

Object individuation studies have been a valuable tool in understanding the development of kind concepts. In this article, we review evidence from object individuation paradigms to argue that by their first birthday, infants represent at least three superordinate-level sortal kinds: OBJECT, ANIMATE, and AGENT (possibly also ARTIFACT). These superordinate sortal-kind concepts share key characteristics of adult kind concepts, such as prioritizing causal properties and having inductive potential. We then discuss the implications of this body of research. First, we discuss how the early development of these sortal-kind concepts (i.e., OBJECT, ANIMATE, and AGENT) relate to the two major theories of concepts: core knowledge and psychological essentialism. Second, we suggest that superordinate kind concepts set the stage for later development of basic-level kind concepts and present evidence that human communication, either in the form of language or pedagogical demonstration, plays a key role in constructing basic-level kinds. Third, we compare feature-based versus kind-based object individuation studies and put forth the hypothesis that they may reflect two modes of construal theory. Last, we discuss several open theoretical and empirical questions about sortal-kind concepts and suggest directions for future research. Overall, our review underscores the importance of object individuation methods as a powerful research tool for investigating the development of kind concepts, mechanisms of learning, and the relationship between language and thoughts.