Final answer:
Object permanence is the understanding that objects continue to exist even when they cannot be seen and is developed during the early sensorimotor stage. This cognitive milestone, identified by Jean Piaget, typically emerges in infants between 5 and 8 months old and coincides with the development of stranger anxiety. Subsequent research suggests even very young infants may have some understanding of object properties earlier than Piaget's stages indicate.
Step-by-step explanation:
Object permanence is a significant cognitive milestone during early childhood development, first identified by the developmental psychologist Jean Piaget. This concept refers to a child’s understanding that objects continue to exist even when they are not visible. Piaget proposed that babies acquire object permanence in the sensorimotor stage, which occurs from birth to approximately 2 years of age. Initially, infants lack the comprehension that objects have a continuous existence outside of their immediate perception. However, typically between 5 and 8 months, infants start to develop object permanence, indicating that they begin to remember and think of objects even after the objects have been removed from sight.
For instance, when infants see a toy and it is subsequently hidden under a blanket, those who have developed object permanence will search for it, whereas those who have not will seem puzzled or indifferent towards the obscured toy. This developmental change marks the beginning of a more complex understanding of the world, forming the basis for later cognitive abilities. As toddlers, having mastered object permanence, children show enjoyment in games like hide and seek, and they recognize that people who leave the room will return. Moreover, around the same time they achieve object permanence, children begin to show stranger anxiety when they cannot fit new individuals into their existing mental schemes.
Research has evolved since Piaget’s times, with studies demonstrating that infants may have some level of object understanding even earlier than Piaget suggested. For example, findings by Baillargeon suggest that children as young as 3 months old can exhibit awareness of object properties without direct interaction, challenging Piaget's timeline of cognitive development stages.