Final answer:
Object permanence, as defined by Jean Piaget, is the understanding that objects continue to exist even when they are not visible.
Step-by-step explanation:
According to Jean Piaget, object permanence is the understanding that something continues to exist even when you cannot see or touch it. This concept is a crucial part of the sensorimotor stage of a child's development, which lasts from birth to about 2 years old. During this stage, children learn about the world through their senses and motor behavior. For example, research has demonstrated that very young children do not show signs of object permanence; they act as if a hidden object no longer exists. However, between 5 and 8 months old, a child typically develops object permanence, meaning they start to understand that objects out of sight still exist. Piaget illustrated this through experiments where infants would search for a toy hidden under a blanket if they had developed object permanence, while those who had not would appear confused.