Infants' perception of concavity and convexity of shaded objects

The discriminative sensitivities of 30 4-month-old and 30 8-month-old infants for concave and convex objects were measured using the preferential-looking method. Five cylinder-like objects with different magnitudes of concave or convex shaded surfaces and outline contours were presented to the infants in pairs. The results indicated that the 4-month-old infants could discriminate better between object convexities than between object concavities. In contrast, the 8-month-old infants were able to equally discriminate between object concavities and object convexities, and their sensitivity to both object concavity/convexity was much higher than that of the 4-month-old infants. This difference in the sensitivity to object concavity and convexity suggested that younger and older infants might have differential abilities for cue utilization for recovering object structures.