The Acquisition of Conservation of Substance and Weight in Children

Smedslund, J. The acquisition of conservation of substance and weight in children. VII. Conservation of discontinuous quantity and the operations of adding and taking away. Scand. J. Psychol ., 1962, 3 , 69–77.—In Exp. I a test of conservation and highly different items of addition and subtraction were given. Conservation was closely related only to an item involving a subtraction of a piece and a subsequent addition of the same piece (‐ + sequence), followed by an addition of a piece and the subsequent subtraction of the same piece (+ ‐ sequence). In Exp. II a test of conservation was given together with items involving various combinations of simple ‐ + and + ‐ sequences. It is concluded that ‐ +, + ‐, and conservation seem to form a genetic sequence in this order, thus strengthening the hypothesis that a concept of conservation reflects a complete reversibility of the operations of + and ‐.