Infants' use of speed information to individuate objects in occlusion events

The present research investigated infants' ability to use speed information to individuate objects in occlusion events. In Experiment 1, 7.5- and 4.5-month-olds were presented with a discontinuous-speed occlusion event; the screen was then lowered and infants saw a single object on the platform. The infants responded as if they (a) concluded that two objects were involved in the event; (b) expected to see two objects when the screen was lowered; and (c) were surprised when this expectation was violated. In Experiment 2, 4-month-olds were tested using the same procedure and negative results were obtained, a finding consistent with those of Spelke, Kestenbaum, Simons, and Wein (1995). Experiment 3 explored whether younger infants might reveal an ability to use speed information if a different, more sensitive, individuation task was used; positive results were obtained. Together, these results suggest that speed of motion is fundamental to the individuation process. (C) 2003 Elsevier Science Inc. All rights reserved.