Infant Perception of Surface Texture and Relative Height as Distance Information: A Preferential-Reaching Study

Two preferential-reaching experiments explored 5- and 7-month-olds' sensitivity to pictorial depth cues. In the first experiment, infants viewed a display in which texture gradients, linear perspective of the surface contours, and relative height in the visual field provided information that two objects were at different distances. Five- and 7-month-old infants reached preferentially for the apparently nearer object under monocular but not binocular viewing conditions, indicating that infants in both age groups respond to pictorial depth cues. In the second experiment, texture gradients and linear perspective of the surface contours were eliminated from the experimental display, making relative height the sole pictorial depth cue. Seven-month-olds again reached more often for the apparently nearer object under monocular, but not binocular viewing conditions. By contrast, the 5-month-olds' reaching behavior did not differ between viewing conditions. These results indicate that 7-month-olds respond to the depth cue of relative height but provide no evidence of responsiveness to relative height in 5-month-olds. Both age groups responded more consistently to pictorial depth in Experiment 1 than in Experiment 2.