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Developmental Changes in Infant Spatial Categorization: When More Is Best and When Less Is Enough


  • This research was supported by NSF PECASE Award BCS-0349183 awarded to the first author. We thank the families who generously gave their time to participate in the present studies. We also are indebted to the undergraduate students at the Cornell Infant Studies Lab, particularly Alex Yang and Aarti Agarwal, for their help in recruiting and testing infants. Finally, we wish to acknowledge Yoo Mee Lee, Michelle Duong, Emilie Stewart, Taylor Daughtery, and Kyu-Ri Lee for their help with interrater reliabilities.

Correspondence concerning this article should be addressed to Marianella Casasola, Department of Human Development, B51 MVR Hall, Cornell University, Ithaca, NY 14853. Electronic mail may be sent to


Two experiments examined infants' ability to form a spatial category when habituated to few (only 2) or many (6) exemplars of a spatial relation. Sixty-four infants of 10 months and 64 infants of 14 months were habituated to dynamic events in which a toy was placed in a consistent spatial relation (in or on) to a referent object. At 10 months, infants formed a spatial category (looking longer at an unfamiliar than familiarized spatial relation) only when habituated to 6 exemplars. At 14 months, infants formed the spatial category regardless of the number of habituation exemplars. The results highlight developmental changes in infant spatial categorization and show that increasing exemplar number facilitates this ability in infants of 10 months.

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