An experimental analysis of the criteria used by children to judge quantities

This study was an attempt to investigate the ability of various groups of children to classify containers which were unequal to an original container. Material was poured from an original container (O) into a new container (I) of the same quantity but different height and breadth. A series of standard containers equal to I in diameter but either shorter or taller was placed between O and I. The S was asked whether the standards would overfill or underfill O. In a control condition Ss did not know that O and I were equal in quantity. Not only Ss with consrvation but also nonconservation Ss performed better in the experimental condition than in the control condition, provided the Ss were over 5 years of age. Ss under 5 years of age showed no difference between experimental and control treatments. The results were interpreted as showing that as from the age of 5 years, Ss construct a classifiactory system which provides logical criteria for judging the quantity of containers. This classfiactory system corresponds to the conjunction of heights and breadths.