Is the top object adequately supported by the bottom object? young infants' understanding of support relations

Three experiments examined 7.5- to 9.5-month-old infants' ability to distinguish between adequate and inadequate support. The infants in Experiment 1 saw a small box that was centered between and supported by two larger boxes. Neither of the larger boxes alone provided adequate support for the small box. Prior to the experiment, the infants were shown that the small box was either separate from or attached to the left box. All infants saw the same test event: The right box moved to the right, past the right edge of the small box, which then rested on the left box. The infants who had seen the small box as separate looked reliably longer at the test event, suggesting that they realized that the left box alone did not provide adequate support for the small box and hence were surprised at the small box's failure to fall. The infants in Experiment 2 saw two identical boxes placed side by side. A larger box was placed on the right box with their right edges aligned; the left corner of the large box rested on the left box. The right box alone provided adequate support for the large box but the left box did not. The infants saw two test events. In one (possible) event, the left box moved past the left edge of the large box, which then rested on the right box. In the other (impossible) event, the right box moved past the right edge of the large box, which then rested on the left box. The infants looked reliably longer at the impossible than at the possible event, suggesting that they understood that the left box alone did not provide adequate support for the large box and hence were surprised that the large box did not fall when the right box moved to the side. Experiment 3 tested the generality of these findings using a more difficult problem. The results were negative, indicating that infants' ability to distinguish between adequate and inadequate support is initially limited.