Critiques findings and interpretations of an investigation of the role of schooling and urbanization on the acquisition of conservation of physical quantities in Senegalese children. Concludes that the investigation showed a smaller impact of schooling, even in the rural milieu, than a previous study of Senegalese children. (RJC)

Investigated the role of schooling and urbanization on the acquisition of conservation of physical quantities in 384 Senagalese children of 7, 9, 11, and 13 years. Results revealed functional divergences in the acquisition of physical quantities. (RJC)

Explores two hypotheses about the effect of symbolic systems on psychological functions: (1) culturally elaborated systems of signs affect psychological functioning in a general way; and (2) systems of signs, when used to support skilled action, affect the organization of human activity. Reviews research that supports the second hypothesis. (LB)