Final answer:
Young children do not have object permanence, which is Piaget's concept describing a child's understanding that objects continue to exist even when not in sight. This cognitive skill develops in the sensorimotor stage by around 2 years of age.
Step-by-step explanation:
According to Jean Piaget, young children lack object permanence, which is the understanding that objects continue to exist even when they are not being observed. This cognitive milestone is typically developed during the sensorimotor stage of cognitive development, which lasts from birth until about 2 years of age. When a child grasps a toy, it's part of their experience and feels real, but once the toy is out of sight, children who have not yet developed object permanence may behave as if it no longer exists.
Piaget's research indicated that very young infants do not demonstrate object permanence. However, more recent studies have suggested that even very young children have some understanding of objects and their properties earlier than Piaget proposed. For example, infants have been observed to show surprise when witnessing events that defy their expectations of solid objects, such as an object passing through another object, which suggests an early form of understanding regarding the permanence and solidity of objects.