Infants 8.5 and 9.5 months of age were tested for ability to determine the location of an object hidden in one of two covered containers before their left-right positions were reversed. Only the older infants provided with different colored covers to their containers were able to do this task. (Author/DB)

This is volume 3 of the series of translations of books from the Soviet literature on research in the psychology of mathematics instruction and on teaching methods influenced by the research. This volume presents a detailed and careful technical analysis of the constituent aspects underlying spatial thinking as well as interesting reports of…