Piaget's stages of development refer to a description of the normal development of a person from infant to adult. The stage in which the child has just develop object permanence is the sensorimotor stage that is a period from birth through 18-24 months in which the infant at first only have awareness of what it is in front of him/her. In this stage, chldren start to experiment with different things and they begin to understand that objects exists and that sometimes they can't see them and this is known as object permanence.
Jean Piaget was the one who came up with the <span>four stages of intellectual (or cognitive) development and these are sensorimotor, pre operational, concrete operational and formal operational. The state in which a child has developed object permanence by the end of the sensorimotor stage. Hope this answers your question.</span>
