Psychological essentialism is a folk theory characterized by the belief that a causal internal essence or force gives rise to the common outward behaviors or attributes of a category's members. In two studies, we investigated whether 4- to 7-year-old children evidenced essentialist reasoning about heart transplants by asking them to predict…

Despite the well-established literature on explanation in early childhood, little is known about what constrains children's explanations. State change and negative outcomes were examined as potential explanatory biases in the domain of naïve biology, extending upon previous work in the domain of naïve physics. In two studies, preschool children…

The goal of the present study was to explore domain differences in young children's expectations about the structure of animal and artifact categories. We examined 5-year-olds' and adults' use of category-referring generic noun phrases (e.g., "Birds fly") about novel animals and artifacts. The same stimuli served as both animals and artifacts;…

The present studies compare young children's explanations and predictions for the biological phenomenon of contamination. In Study 1, 36 preschoolers and 24 adults heard vignettes concerning contamination, and were asked either to make a prediction or to provide an explanation. Even 3-year-olds readily supplied contamination-based explanations,…

Under what circumstances do people agree that a kind-referring generic sentence (e.g., "Swans are beautiful") is true? We hypothesised that theory-based considerations are sufficient, independently of prevalence/frequency information, to lead to acceptance of a generic statement. To provide evidence for this general point, we focused on…

Evaluating whether a limited sample of evidence provides a good basis for induction is a critical cognitive task. We hypothesized that whereas adults evaluate the inductive strength of samples containing multiple pieces of evidence by attending to the relations among the exemplars (e.g., sample diversity), six-year-olds would attend to the degree…

Two studies (N = 456) compared the development of concepts of animal species and human gender, using a switched-at-birth reasoning task. Younger children (5- and 6-year-olds) treated animal species and human gender as equivalent; they made similar levels of category-based inferences and endorsed similar explanations for development in these 2…

Preschoolers use information from interventions, namely intentional actions, to make causal inferences. We asked whether children consider some interventions to be more informative than others based on two components of an actor's knowledge state: whether an actor "possesses" causal knowledge, and whether an actor is allowed to "use" their…

Determining whether a sample provides a good basis for broader generalizations is a basic challenge of inductive reasoning. Adults apply a diversity-based strategy to this challenge, expecting diverse samples to be a better basis for generalization than homogeneous samples. For example, adults expect that a property shared by two diverse mammals…

Prior research indicates that category labels influence category judgments, but little is known regarding the effects for familiar categories with significant social consequences. The present studies address this issue by examining the effect of linguistic form on judgments of illnesses. Both mental and physical illnesses were presented in each of…

The authors conducted 4 studies suggesting that children attribute different modes of transmission to genetic disorders and contagious illnesses. Study 1 presented preschoolers through 5th graders and adults with "switched-at-birth" scenarios for various disorders. Study 2 presented preschoolers with the same disorders but used contagion links in…

Three studies examined the ability of 8- and 9-year-olds and young adults to use sample monotonicity and diversity information according to the similarity-coverage model of category-based induction. Found that children's difficulty with this information was independent of category level, and may be based on preferences for other strategies…

Reviews selected research on children's early formation of categories. Finds sophistication in how children group objects and think about those groupings. Notes findings related to type of grouping (thematic or taxonomic), multiple classifications, overgeneralization, the role of background knowledge on classification abilities, the…