Abstract
The purpose of this study was to test whether young infants anticipate the reappearance of a moving object that disappears in a manner consistent with dynamic occlusion. We tested 5-, 7-, and 9-month-old infants in a predictive tracking task in which a brightly colored ball rolled horizontally across a large computer-generated display. An occluding screen was placed along the path of the ball so that the ball was hidden for approximately one second as it translated across the display. As the front edge of the ball intersected with the occluding screen, its texture was deleted and it was accreted as the ball began to reappear from the screen (Occlusion condition). Predictive tracking was measured by whether or not infants anticipated the reappearance of the ball after it disappeared behind the screen.
In order to assess whether infants were specifically sensitive to the occlusion information or whether tracking was simply robust enough to withstand a brief interruption in spatiotemporal continuity, three additional conditions were tested: (1) Instantaneous Disappearance/Reappearance; (2) Implosion/Explosion; and (3) Virtual Occlusion (the occluding screen — while functionally present — was not visible). The results revealed evidence of predictive tracking by 7 months of age, but this was true only in the occlusion condition. These results will be discussed in terms of the specific information necessary for infants to perceive the continuing existence of objects that disappear for brief periods of time.