From early in development, children use categories to learn about the world around them. For example, upon learning something about an individual (e.g., that a spider bites), children can generalize this information to the category as a whole (e.g., all spiders), and use this information to guide behavior (e.g., to avoid spiders). A critical--and often useful--assumption that underlies this form of reasoning is the belief that members of a category are highly similar to each other. Yet, this assumption can also lead children astray. For example, if children assume that all dogs are friendly because their own cocker spaniel is friendly, they may engage in dangerous behavior if they encounter a vicious dog. Effective induction thus must balance the belief that category members are similar to each other with the recognition that categories also include important variability. These studies examine how the balance between these beliefs contributes to developmental changes in learning across childhood. These studies test the hypotheses that (a) younger children (preschool-age) tend to overlook within-category variability, leading them to over-generalize new information, (b) children recognize more within-category variability as they get older, leading to more efficient inductive learning, and (c) guiding younger children to recognize the importance of within-category variability helps them to learn more efficiently.
This research aims to uncover the cognitive developmental processes that lead children to generalize information more or less effectively. In doing so, this research has three immediate implications for education. First, these studies aim to identify a strategy--instruction on within-category variation--that can lead children to generalize information more accurately and efficiently, which could be implemented in a range of educational contexts. Second, these studies illustrate the developmental factors that contribute to children's understanding of a key component of the scientific method--that it is important to obtain converging evidence from diverse sources before drawing a broad conclusion--and thus have implications for how to teach about the scientific method effectively. Third, because reasoning about variability is central to a conceptual understanding of evolution, this work will examine an important developmental factor that should be addressed in the design of science curricula. These studies speak to the key theoretical question of how the mechanisms by which humans acquire new knowledge change across development, and thus have broad theoretical significance for cognitive and developmental psychology. This research also supports extensive training opportunities for students and educational opportunities for families and educators.
