Running head: THE ROLE OF ONTOLOGICAL BELIEFS IN EARLY CATEGORIZATION Preschool ontology: The role of beliefs about category boundaries in early categorization

These studies examined the role of ontological beliefs about category boundaries in early categorization. Study 1 found that preschool-age children (N= 48, ages 3-4) have domainspecific beliefs about the meaning of category boundaries; children judged the boundaries of natural kind categories (animal species, human gender) as discrete and strict, but the boundaries of other categories (artifact categories, human race) as more flexible. Study 2 demonstrated that these domain-specific ontological intuitions guide children’s learning of new categories; children (N = 28, 3-year-olds) assumed that the boundaries of novel animal categories would be narrower and more strictly defined than novel artifact categories. These data demonstrate that abstract beliefs about the meaning of category boundaries shape early conceptual development. Preschool Ontology 3 Preschool ontology: The role of beliefs about category boundaries in early categorization Adult categories are embedded in systematic, domain-specific ontological beliefs about the structure of the world (Murphy & Medin, 1985). In particular, adults view some categories (e.g., mammals) as reflecting objective reality, and others (e.g., tools) as more subjective and flexible (Gelman & Coley, 1991; Kalish, 1998; Malt, 1990; Rhodes & Gelman, 2009a). This ontological distinction has implications for a number of cognitive processes, including categorization (e.g., adults view membership in the category mammal as absolute, but allow for partial membership in the category tool; Diesendruck & Gelman, 1999; Estes, 2003, 2004) and induction (e.g., adults expect mammals to share many underlying similarities, but tools to be more variable; Gelman, 1988; Gelman & O’Reilly, 1988). The present research examines the role of these ontological intuitions in early conceptual development. The extent to which young children incorporate abstract theories into their concepts continues to be an area of ongoing debate. According to traditional theories, young children’s categories are atheoretical, based on superficial similarities, and do not reflect abstract concepts (Piaget, 1929). Contemporary researchers from this perspective suggest, for example, that early induction is based on perceptual similarity, not abstract conceptual categories (Sloutsky & Fisher, 2004; Sloutsky, Kloos, & Fisher, 2007). In contrast, others have argued that early concepts are grounded in rudimentary domain-specific theories, and that these abstract theories guide and propel conceptual development (Gelman & Koenig, 2003; Wellman & Gelman, 1992). In support of this second position, two recent studies provide direct evidence that, by age five, children share adults’ domain-specific ontological beliefs. Rhodes and Gelman (2009a) found evidence of domain-specificity in children’s beliefs about category objectivity; in this Preschool Ontology 4 work, 5-year-olds rejected animal categories that were inconsistent with their own beliefs about how to categorize animals, but were more likely to accept unusual ways of categorizing artifacts. This pattern suggests that children view animal categorization as objective, but artifact categories as more subjective and flexible. Similarly, Rhodes and Gelman (2009b) found that 5-year-olds rejected the possibility of partial membership in animal categories (e.g., they responded that something cannot be “sort of a bird”), but accepted this possibility for artifacts (e.g., they responded that something can be “sort of a tool”). Thus, 5-year-olds have domain-specific intuitions about both the discreteness and objectivity of category boundaries. The studies described above indicate that children’s categories are embedded in rudimentary ontological theories by the early school-age years. The goal of the present work is to examine whether these theories play a role in shaping early conceptual development. This research extends prior work in two key ways. First, the present studies examine the ontological intuitions of younger preschool-age children. Because the previous studies examined early school-age children (age 5), it remains unclear from prior work whether domain-specific ontological beliefs shape early conceptual development, or alternately, whether such beliefs develop only after a period of conceptual reorganization during the preschool years (cf. Carey, 1995). Previous work has demonstrated that younger preschoolers have many systematic domain-specific beliefs about animals and artifacts, including about how category membership is determined (Disendruck, Markson, & Bloom, 2003; Gelman & Kremer, 1991), category stability (Gelman & Wellman, 1991; Keil, 1989; Siegel & Callanan, 2007), characteristic properties (Simons & Keil, 1995), and causal processes (Hatano & Inagaki, 1994; Massey & Gelman, 1988; Rosengren, Gelman, Kalish, & McCormick, 1991). Yet, whether preschoolers have systematic ontological beliefs about category boundaries (e.g., viewing some categories as more Preschool Ontology 5 objective and discrete than others) has not been addressed in prior work. Thus, the present studies directly test whether preschoolers have such beliefs. Second, the present studies examine whether children’s ontological intuitions influence how they learn about new categories. If children believe that the boundaries of animal categories are strict and objectively defined—and this belief contributes to how children make sense of the world—then when they encounter a new animal category, they should assume that its boundaries have this status. Thus, children should treat membership in new animal categories as strict and discrete, and should assign category membership conservatively. In contrast, children should assume that the boundaries of new artifact categories are relatively subjective and graded, and thus, assign category membership more flexibly. No prior work, however, has examined whether children’s ontological intuitions guide how children view the boundaries of new categories (see Barrett, Abdi, & Murphy, 1993; Booth & Waxman, 2002; Brandone & Gelman, 2009; Greif, Kemler-Nelson, Keil, & Guitierrez, 2006; for related work). Thus, it remains unclear whether ontological intuitions shape how children learn about categories, or alternately, whether these intuitions develop only after children have specific experiences with or knowledge about particular categories (e.g., after repeated experiences seeing birds categorized in a uniform way and tools categorized more variably). The Present Studies Study 1 tests whether preschoolers’ ontological beliefs about the status of category boundaries vary by domain. To do so, Study 1 assesses preschoolers’ beliefs about familiar categories, similar to those used by Rhodes and Gelman (2009a), using a new task designed for younger children. This study included two domains that Rhodes and Gelman (2009a) found that 5-year-olds construe as objective (animal species and human gender) and two domains that 5Preschool Ontology 6 year-olds construe as subjective and flexible (artifact categories and human race). Study 2 tests whether preschoolers rely on domain-specific ontological intuitions when learning about new categories, by examining novel animals and artifacts. Study 1