Generic Language Use Reveals Domain Differences in Children's Expectations about Animal and Artifact Categories

The Formal Structure of Kind Representations

Kind representations, concepts like table, triangle, dog, and planet, underlie generic language. Here, we investigate the formal structure of kind representations-the structure that distinguishes kind representations from other types of representations. The present studies confirm that participants distinguish generic-supporting properties of individuals (e.g., this watch is made of steel) and accidental properties (e.g., this watch is on the nightstand). Furthermore, work dating back to Aristotle establishes that only some generic-supporting properties bear a principled connection to the kind, that is, are true of an individual by virtue of its being a member of a specific kind (e.g., telling time for a watch). The present studies tested the hypothesis that principled connections are part of the formal structure of kind representations. Specifically, they tested whether they structure a newly learned kind representation. Experiment 1 found that introducing a property of a newly encountered novel kind in any one of four linguistic frames that provide evidence that a property has a principled connection to a kind (e.g., "It has fur because it is a blick") led participants to infer a different conceptual consequence of principled connections (i.e., "There is something wrong with this blick, which does not have fur") for which they had no direct evidence. Two introduction frames that provided no evidence for principled connections (e.g., "Almost all blicks have fur") did not generate the same consequence. Experiment 2 found that all of the targeted properties were generic licensing, irrespective of the introduction frame. That the distinction between properties that bear principled connections to their kinds, and merely generic-supporting properties structures novel kind representations, provides strong evidence that this distinction is part of the formal structure of kind representations.

FN400 amplitudes reveal the differentiation of semantic inferences within natural vs. artificial domains

Category-based inferences allow inductions about novel properties based on categorical memberships (e.g., knowing all trout have genes [premise] allows us to infer that all fish have genes [conclusion]). Natural (N) and artificial (A) domains are the most obvious and traditional distinctions in categorization. The distinct event-related potential (ERP) responses for N and A domains have not yet been examined during category-based inferences. In this study, the differences between ERP inference parameters within N and A domains were measured during inductive decision processing, while controlling the premise−conclusion similarity and premise typicality between those two domains. Twenty-two adults were asked to make a decision on whether a conclusion was definitely weak, possibly weak, possibly strong, or definitely strong, based on a premise. The behavioral results showed that semantic inferences within the N domain shared similar inductive strength, similar “correct” response rates, and similar reaction times with that within the A domain. However, the ERP results showed that semantic inferences elicited smaller frontal-distributed N400 (FN400) amplitudes within the N domain than within the A domain, which suggested that knowledge of the ontological domain of a category affects category-based inferences, and underlaid the increased categorical coherence and homogeneity in the N as compared to the A categories. Therefore, we have distinguished the cognitive course of semantic inferences between N and A domains.

The Development of Preschoolers' Living Kinds Concept: A Longitudinal Study

Given limitations in the integrative scope of past research, basic questions about the organization and development of preschoolers' living kinds concept remain open to debate. This study was designed to address past limitations through use of a longitudinal design, extensive stimulus set, and alternate indices of understanding. Thirty-five English-speaking 3-year-olds from middle-class families in Albuquerque, NM participated in four testing sessions over 1 year. Indices of understanding included statements that preschoolers generated about various living and nonliving objects, biological properties they attributed to the objects, and their characterization of objects as "alive" or not. Results reveal a multifaceted picture of developmental change in preschoolers' living kinds concept involving both the construction and elaboration of a core biological understanding.

Memory for generic and quantified sentences in Spanish-speaking children and adults

Generic language ( Owls eat at night) expresses knowledge about categories and may represent a cognitively default mode of generalization. English-speaking children and adults more accurately recall generic than quantified sentences ( All owls eat at night) and tend to recall quantified sentences as generic. However, generics in English are shorter than quantified sentences, and may be better recalled for this reason. The present study provided a new test of the issue in Spanish, where generics are expressed with an additional linguistic element not found in certain quantified sentences ( Los búhos comen de noche 'Owls eat at night' [generic] vs. Muchos búhos comen de noche 'Many owls eat at night' [quantified]). Both preschoolers and adults recalled generics more accurately than quantified sentences, and quantified sentences were more often recalled as generic than the reverse. These findings provide strong additional evidence for generics as a cognitive default, in an understudied cultural context.

Changes in Beliefs About Category Homogeneity and Variability Across Childhood

Effective category-based induction requires understanding that categories include both fundamental similarities between members and important variation. This article explores 4- to 11-year-olds' (n = 207) and adults' (n = 49) intuitions about this balance between within-category homogeneity and variability using a novel induction task in which participants predict the distribution of a property among members of a novel category. Across childhood, children learned to recognize variability within categories-showing increasing sensitivity to the role of property type and domain in constraining inferences. Children below the age of 6 showed evidence for a domain-general assumption that categories are homogeneous-generalizing properties broadly to 100% of category members. These studies support important developmental changes in category representations that may influence category-based induction.

Artifacts and essentialism

Psychological essentialism is an intuitive folk belief positing that certain categories have a non-obvious inner "essence" that gives rise to observable features. Although this belief most commonly characterizes natural kind categories, I argue that psychological essentialism can also be extended in important ways to artifact concepts. Specifically, concepts of individual artifacts include the non-obvious feature of object history, which is evident when making judgments regarding authenticity and ownership. Classic examples include famous works of art (e.g., the Mona Lisa is authentic because of its provenance), but ordinary artifacts likewise receive value from their history (e.g., a worn and tattered blanket may have special value if it was one's childhood possession). Moreover, in some cases, object history may be thought to have causal effects on individual artifacts, much as an animal essence has causal effects. I review empirical support for these claims and consider the implications for both artifact concepts and essentialism. This perspective suggests that artifact concepts cannot be contained in a theoretical framework that focuses exclusively on similarity or even function. Furthermore, although there are significant differences between essentialism of natural kinds and essentialism of artifact individuals, the commonalities suggest that psychological essentialism may not derive from folk biology but instead may reflect more domain-general perspectives on the world.