During which developmental stage do children typically begin to understand object permanence?

Object permanence is the understanding that objects continue to exist even when they cannot be seen or heard. This cognitive milestone typically develops during the infancy stage, particularly between the ages of 4 to 7 months. Infants start to exhibit signs of understanding that objects are permanent, which is assessed through simple experiments, such as hiding a toy under a blanket and observing whether the infant searches for it.

In the context of childhood development theories, such as those proposed by Jean Piaget, this stage is crucial as it lays the foundation for further cognitive processes and indicates a developing awareness of the world around them. The successful grasp of object permanence is a key indicator of cognitive progress during this early stage, emphasizing the stark contrast with later stages such as early childhood, preschool, or adolescence, where different cognitive skills and understandings are being developed.