In defense of core competencies, quantitative change, and continuity.

J. Kagan (2008) urges contemporary developmentalists to (a) be cautious when attributing conceptual knowledge to infants based on looking-time performance, (b) constrain their interpretation of infant performance with multiple methodologies, and (c) reconsider the possibility that qualitative development may be the path by which perceptual infants become conceptual adults. This commentary outlines an account of conceptual development that adheres to two of the three Kagan provisos. It is (a) circumspect in the core competencies attributed to infants and (b) grounded in convergent measures including looking time, event-related potentials, computational modeling, and eye tracking, but (c) maintains that the transition from the perceptually based category representations of infants to the knowledge-rich concepts of adult is a continuous developmental process marked by quantitative change.