Infants' responsiveness to line junctions in curved objects.

Several empirical studies demonstrate that infants under 6-7 months of age are unable to extract static-monocular depth information from their environment. The aim of this study was to extend these findings by using a three-dimensional structure indicated by curved Y junctions. Infants 5 and 8 months of age were habituated to the line drawing of a cylinder. During test trials, the infants viewed two displays, one in which a surface marking had been deleted from the habituation figure and one in which an edge had been erased. An ANOVA revealed that the 8-month-old subjects looked significantly longer at the dishabituation display lacking the edge, whereas the 5-month-olds did not. The results provide evidence that 8-month-old infants distinguish between lines indicating edges and lines indicating markings and that they are able to use line junctions to perceive line drawings as depictions of three-dimensional objects in the picture plane. Copyright 1999 Academic Press.