Answer:
object permanence
Explanation:
Renée Baillargeon body of work on psychology mainly revolves around development of cognition during infancy.
Piaget's study showed that object permanence in children developed around 8-12 months. The experiment used to study this hypothesis objects were hidden and the amount of time the infant looked for the object was observed. He noticed that the fixation that the infants had to find the object was less when compared to infants who were older.
Baillargeon argued that this was because the infants lacked proper motor skills. She measured the fixation times the infants had to impossible events and compared them to possible events.