Pascual-Leone's neo-Piagetian theory of development is used to predict the pre- and postinstruction distributions of scores on a subject-controlled digit placement task as a function of three parameters dealing with mental strategy and capacity. (Author/ED)

In this study an attempt was made to obtain a developmental dimension for estimating longitudinal development on the basis of cross-sectional data. To check the validity of this approach, the cross-sectional data were compared with true longitudinal data. Forty-three public school children were given a series of conservation tasks in four…