Intuitions about support in 4.5-month-old infants.

The present experiment examined whether 4.5-month-old infants expect an object to fall when its support is removed. The infants saw two test events: a possible and an impossible event. In the possible event, a hand deposited a box fully on a platform and then withdrew, leaving the box supported by the platform. In the impossible event, the hand deposited the box beyond the platform and then withdrew, leaving the box suspended in mid-air with no apparent source of support. The infants looked reliably longer at the impossible than at the possible event, suggesting that they expected the box to fall in the impossible event and were surprised that it did not. Evidence for this interpretation was provided by the results of two control conditions. In one, the box fell when released by the hand beyond the platform. In the other, the hand retained its grasp on the box throughout the events, thereby providing continuous support for it. The infants in these two conditions tended to look equally at the test events. Together, these results indicate that, like adults, 4.5-month-old infants realize that objects cannot remain stable without support.