Children's ability to order and orient objects.

Difficulty of copying the order of a set of objects is shown to vary with the plane in which they are ordered; piles are easier than left-right arrays. Difficulty of copying the orientation of a single object is shown to vary with the relative position of sample and copy; reproductions of a figure around its axis of symmetry are easier than other reproductions. Difficulty of ordering objects had previously been shown to depend on relative position. Difficulty of orienting single objects had previously been shown to depend on plane. Development of these 2 abilities apparently depends on common underlying factors.