From infant to child: the dynamics of cognitive change in the second year of life.

The authors review several key areas of early cognitive development in which an abrupt shift in ability at the end of the second year of life has been traditionally assumed. These areas include deferred imitation, self-recognition, language, and categorization. Contrary to much conventional theorizing, the evidence shows robust continuities in all domains of early cognitive development. Where there is evidence of a reorganization of behavior that makes a new level of performance possible, dynamic-systems analyses indicate that even these may be driven by underlying processes that are continuous. Although there remain significant definitional and methodological issues to be resolved, the outcome of this review augers well for newer models in which cognitive development is viewed as a continuous, dynamic process.