In a Study by Baillargeon and Colleagues, 9-Month-Old Infants Watched

Essay

In a study by Baillargeon and colleagues, 9-month-old infants watched an experimenter either lower a tall object inside a short container until it became fully hidden (containment condition) or lower a short cover over the same object until it became fully hidden (covering condition). The infants detected the violation in the containment but not the covering condition. However, at 12 months of age, infants also succeeded in the covering condition. What do these findings tell us about infants' understanding of the physical world? How do they relate to Piaget's stage theory?