In a study with 79 3-year-olds, we confirm earlier findings that separating the sorting dimensions improve children's performance on the Dimensional Change Card Sorting (DCCS) task. We also demonstrate that the central reason for this facilitation is that the two sorting dimensions are not integral features of a single object. Spatial separation of the sorting dimensions has no additional significant influence. This finding highlights the important role of objects with respect to children's attentional flexibility. Implications for current theories on the DCCS task and for the development of perspective taking and cognitive flexibility are discussed. (Contains 2 figures and 1 table.)