Mental spatial transformations in 14- and 16-month-old infants: effects of action and observational experience.

Infants' ability to mentally track the orientation of an object during a hidden rotation was investigated (N = 28 in each experiment). A toy on a turntable was fully covered and then rotated 90°. When revealed, the toy had turned with the turntable (probable event), remained at its starting orientation (improbable event in Experiment 1), or turned to the opposite side (improbable event in Experiment 2). Results demonstrated a developmental progression between 14 and 16 months of age in infants' sensitivity to spatial object relations and their ability to track the orientation of an object during hidden rotation. Experiment 3 showed that 14-month-olds' performance improved with hands-on training, highlighting the role of action experience in cognitive development.