Infants ranging in age from six months to eight months were shown repeated instances of real object movement-disappearance-reappearance. Results suggest that the key changes in early cognitive development rest primarily upon the infant's gradual adaptation of old responses through encounters with new events--rather than upon the acquisition of…

Based on the more general principle that all thinking (including reasoning) is basically perceptual in nature, the author proposes that visual perception is not a passive recording of stimulus material but an active concern of the mind. He delineates the task of visually distinguishing changes in size, shape, and position and points out the…