Understanding fraction magnitudes is foundational for later math achievement. To represent a fraction x/y, children are often taught to use "partitioning": Break the whole into y parts and shade in x parts. Past research has shown that partitioning on number lines supports children's fraction magnitude knowledge more than partitioning on…

I argue that emotion research needs formal (mathematical) theory to address two central questions. How does evolution shape mechanisms of emotion development across generations, depending on environmental conditions? How do these mechanisms generate emotions, based on lifetime experience and current context? Formal modeling enables researchers to…

In 2 studies, the authors examined the development of the relationship between inductive reasoning and visual recognition memory. In both studies, 5- to 6-year-old children and adults were shown instances of a basic-level category (dogs) followed by a test set containing old and new category members that varied in their similarity to study items.…

The relationship between complexity and usefulness can be captured by a U-shaped curve. This comment explores that relationship. Complexity may be useful for one of the main aims of developmental psychology (causal inference) but not for another (description of developmental phenomena). Currently, developmentalists conduct complex analyses that…

Children (N = 157) 4 to 8 years old participated 1 time (single) or 4 times (repeated) in an interactive event. Across each condition, half were questioned a week later about the only or a specific occurrence of the event ("depth first") and then about what usually happens. Half were prompted in the reverse order ("breadth first"). Children with…

Applies the confluence model to a longitudinal intact family data set. Also tests the data with simple linear models. Results suggest that the confluence model should be rejected as a useful model for these data based on principles of parsimony and predictability. (Author/AS)

Authors demonstrate that a simple algebraic analysis renders previous interpretations superfluous, making overlap" a tautology and not a hypothesis. (Authors/MB)

The concepts of quantitative and structural change are considered from a multivariate perspective. A hybrid of these two types of change, quantistructural change, is described. (CS)

Presents a mathematical model of the development of reaching behavior in infants, along with the results of two experiments that showed that infant movements could be decomposed into the underlying submovements using a principled method; and the angular error in infant reaches matches the form and magnitude of error assumed by the model. (MDM)

Examined gender differences in 514 children's competence and value beliefs from first through twelfth grade, and the relation of these trends to initial differences in parents' perceptions of children's ability. Found that gender differences in competence and value beliefs related to sports and mathematics. Gender differences in competence beliefs…