The role of quantification operators in the development of conservation of quantity

An analysis of the quantitative processes underlying conservation of quantity is presented. Models of quantitative operators (subitizing, counting, estimation) are derived from adult performance in quantification tasks, and some features of the operators are described. The emergence of conservation is described in terms of the development of the operators and a set of rules which evoke them and coordinate their results. Empirical data related to the developmental argument is discussed.