Research results reported in this special issue show that egocentricity and staging, both central ideas in the Piaget-Kohlberg account of human development, are myths. The appearance of egocentricity and staging can be accounted for by a subtle combination of ethnocentricity and the effects of inappropriate methodologies. (RM)

Piaget, in describing the sequence of classificatory development, describes class inclusion as composed of two processes; hierarchical classification and post-whole comparisons. In the experiment reported here, elementary school children, trained in the concept of sets in first grade mathematics were given a task where they were required to assess…

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…