The overall objectives of this research are two-fold: to determine the effect which systematic variation of model and photographic stimuli have upon children's ability to perceive and to imagine spatial arragements from different points of view; and to investigate the complex behaviors required to perform successfully on a spatial task involving the processing of two- and three- dimensional visual information in order to identify viewpoints. The experiments entail the further development of a board/block spatial task adapted from Piaget's three-mountain task.