In this longitudinal study we examined the stability of exploratory play in infancy and its relation to cognitive development in early childhood. We assessed infants' ( N = 130, mean age at enrollment = 12.02 months, SD = 3.5 months; range: 5–19 months) exploratory play four times over 9 months. Exploratory play was indexed by infants' attention to novelty, inductive generalizations, efficiency of exploration, face preferences, and imitative learning. We assessed cognitive development at the fourth visit for the full sample, (...) and again at age three for a subset of the sample ( n = 38). The only measure that was stable over infancy was the efficiency of exploration. Additionally, infants' efficiency score predicted vocabulary size and distinguished at-risk infants recruited from early intervention sites from those not at risk. Follow-up analyses at age three provided additional evidence for the importance of the efficiency measure: more efficient exploration was correlated with higher IQ scores. These results suggest that the efficiency of infants' exploratory play can be informative about longer-term cognitive development. (shrink)

How should knowledge be analyzed? Compositionally, as having constituents like belief and justification, or as an atomic concept? In making arguments for or against these perspectives, epistemologists have begun to use experimental evidence from developmental psychology and developmental linguistics. If we were to conclude that knowledge were developmentally prior to belief, then we might have a good basis to claim that belief is not a constituent of knowledge. In this review, I present a broad range of developmental evidence from the (...) past decade and discuss some of the implications it has for the proper analysis of knowledge. The orthodox perspective from the developmental literature was one where children fail to understand belief and knowledge concepts until later in childhood, with typical asymmetries in belief attribution and knowledge attribution. But what emerges from both a discussion of newer findings and a contextualization of older findings is a picture of development whereby core competence with belief and knowledge concepts emerges much earlier than previously thought that apparent failures in later childhood may be explained by other aspects of development than conceptual development and that there is no clear evidence that knowledge attributions emerge earlier than belief attributions. (shrink)

Pietraszewski contends that group representations that rely on a “containment metaphor” fail to adequately capture phenomena of group dynamics such as shifts in allegiances. We argue, in contrast, that social categories allow for computationally efficient, richly structured, and flexible group representations that explain some of the most intriguing aspects of social group behaviour.