BRIEF REPORTS How Infants Encode Spatial Extent

This study explores how infants encode an object’s spatial extent. We habituated 6.5-month-old infants to a dowel inside a container and then tested whether they dishabituate to a change in absolute size when the relation between dowel and con-tainer is held constant (by altering the size of both container and dowel) and when the relation changes (by altering only the size of the container but not the dowel). Infants only dishabituated when the relation changed, suggesting that they do not encode the absolute size of either object but only the relation between them. Developmental psychologists have long been interested in the origin of quantita-tive and spatial reasoning in infancy. A central question concerns how young chil-dren encode continuous quantities, such as the size of an object or the distance be-tween two objects. Piaget and his colleagues claimed that infants and young children have a limited capacity to encode quantitative information about continu-ous extent until the emergence of measurement skills during the school-age years (Piaget, Inhelder, & Szeminska, 1960). However, recent studies provide evidence that even infants can encode object extent and distance (Baillargeon, Kotovsky, &amp