Infants' sensitivity to boundary flow information for depth at an edge.

We investigated infants' sensitivity to a recently discovered kinetic depth cue, boundary flow. 5-month-old infants viewed computer-generated displays in which the relation between the motion of a boundary, indicating an edge, and 2 regions of dots on either side of the boundary, indicating surfaces, provided the only information specifying the order of the 2 surfaces in depth. Infants showed a significant reaching preference for the apparently nearer region of the display. Since previous research has demonstrated that infants reach more frequently for the nearer of 2 surfaces, this result indicates that 5-month-old infants are sensitive to boundary flow information for depth at an edge.