20 (1985) 191-208
ELIZABETH S. SPELKE
Universityof Illinois Abstract A new method was devised to test object permanence in young infants. Fivemonth-old infants were habituated to a screen that moved back and forth through a180-degree arc, in the manner of a drawbridge. After infants reached habituation, a box was centered behind the screen. Infants were shown two test events: a possible event and an impossible event. In the possible event, the screen stopped when it reached the occluded box; in the impossible event, the screen moved through the space occupied by the box. The results indicated that infants lookedreliably longer at the impossible than at the possible event. This finding suggested that infants (1) understood that the box continued to exist, in its same location, after it was occluded by the screen, and (2) expected the screen to stop against the occluded box and were surprised, or puzzled, when it failed to do so. A control experiment in which the box was placed next to the screen providedsupport for this interpretation of the results. Together, the results of these experiments indicate that, contrary to Piaget’s (1954) claims, infants as young as 5 months of age understand that objects continue to exist when occluded. The results also indicate that 5-month-old infants realize that solid objects do not move through the space occupied by other solid objects.
*This research was supportedby a grant from the National Institute of Health (HD-13248) to ESS. The data analysis was supported by a grant from the National Science Foundation (SES84-08626) to SW. While working on this research, RI3 was supported by fellowships from the Natural Sciences and Engineering Research Council of Canada and the Qu6bec Department of Education. We thank Judy Deloache and Bob Reeve, for their carefulreading of the manuscript; Marty Banks, Susan Carey, and Paul Harris, for helpful comments on earlier versions of the manuscript; Wendy Smith Born, Sarah Mangelsdorf, and the members of the Infant Lab at the University of Pennsylvania, for their help with the data collection; and Dawn Iacobucci, for her help with the data analysis. **Reprint requests should be sent to RenCe Baillargeon, PsychologyDepartment, University of Illinois at Urbana-Champaign, 603 East Daniel Street, Champaign, IL 61820, U.S.A.
in The Netherlands
R. Baillargeon et al.
1. Background: Piaget’s theory For adults, an object is an entity that exists continuously in time and space: it cannot exist at two separate points in time without havingexisted during the interval between them, and it cannot appear at two separate points in space without having traveled from one point to the other. Do infants share this conception of objects as temporally and spatially continuous? On the basis of detailed observations of infants’ reactions to object disappearances, Piaget (1954) concluded that they do not. For the young infant, Piaget maintained, eachdisappearance amounts to an annihilation and each reappearance to a resurrection. An object is not a permanent entity that continuous to exist while out of sight, but an ephemeral entity that is continually made and unmade: “a mere image which reenters the void as soon as it vanishes, and emerges from it for no objective reason” (p. 11). Piaget discerned six stages in the development of theinfant’s object concept. He claimed that it is not until infants reach the fourth stage, at about 9 months of age, that they begin to endow objects with permanence, as evidenced by their willingness to search for hidden objects. Piaget observed that prior to stage 4, infants do not search for fully hidden objects. If an attractive toy is covered with a cloth, for example, they make no attempt to lift...