Infants and adults use line junction information to perceive 3D shape

Two experiments investigated infants' and adults' perception of 3D shape from line junction information. Participants in both experiments viewed a concave wire half-cube frame. In Experiment 1, adults reported that the concave wire frame appeared to be convex when it was viewed monocularly (with one eye covered) and that it appeared to be concave when it was viewed binocularly. In Experiment 2, 5- and 7-month-old infants were shown the concave wire frame under monocular and binocular viewing conditions, and their reaching behavior was recorded. The infants in both age groups reached preferentially toward the center of the wire frame in the monocular condition and toward its edges in the binocular condition. Because infants typically reach to what they perceive to be closest to them, these reaching preferences provide evidence that they perceived the wire frame as convex when they viewed it monocularly and as concave when they viewed it binocularly. These findings suggest that, by 5 months of age, infants, like adults, use line junction information to perceive depth and object shape.