The concept of object permanence plays an important role in the theory of cognitive development created by psychologist Jean Piaget.
In the sensorimotor stage of development, a period that lasts from birth to about age two, Piaget suggested that children understand the world through their motor abilities such as touch, vision, taste and movement.
Since toddlers lack of object permanence, they don’t know that you are still there hiding behind your hands, and that is why they get so excited when they get to see you again.
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