Five- and seven-month-olds were tested for sensitivity to pictorial interposition in two experiments. Reaching was used as the dependent measure. Seven-month-olds gave evidence of sensitivity to pictorial interposition. In both experiments they showed a significant preference to reach for the pictorially nearer side of a flat interposition display which simulated three overlapping surfaces and showed no reaching preferences when viewing control displays. Five-month-olds' reaching tendencies did not differ significantly between experimental (interpositon) and control conditions in the second experiment. This result indicated that their responses may have been due to nonspatial proximal stimulus variables in the displays. Five-month-olds, therefore, gave no evidence of sensitivity to pictorial interposition. The finding that 7-month-olds are sensitive to pictorial interposition and the failure to find sensitivity in 5-month-olds is consistent with findings from other studies on infants' sensitivity to pictorial depth information. The cumulative results of these studies suggest that sensitivity to pictorial depth information first appears between 5 and 7 months of age.
Bibliographical noteFunding Information:
This research was supported by National Institute of Child Health and Human Development grants to the University of Minnesota’s Institute of Child Development (HD-05027) and to the University’sC enterf or Research in Human Learning (HD-01136). Correspondence concerning the article and requests for reprints should be sent to Albert Yonas, Institute of Child Development, University of Minnesota, 51 East River Road, Minneapolis, MN 55455. The authors thank Isabel Smith and Ann Sorknes for their assistance in collecting data and Kaye O’Geay for typing the manuscript.