Infants perceive spatial structure specified by line junctions.

Lines in drawings can be perceived as the corners where surfaces intersect, outer boundaries of surfaces, or as markings on a surface. In this study infants' ability to distinguish between lines that indicate corners and edges and lines that indicate markings was investigated. Infants aged 7.5 months were habituated to line displays in which the lines specified a three-dimensional cube or two overlapping rectangles. Both displays contained lines indicating corners, edges, and surface markings. After habituation, infants viewed two test displays, one in which the corners or edges were deleted and one in which the surface markings were deleted. Infants looked significantly longer at the displays that lacked the corners or edges. The results suggest that infants attend to lines that depict corners and edges to a greater degree than they attend to lines that depict markings. Infants may do so because corners and edges specify the shapes of objects whereas markings do not.