Final answer:
Josie finds the game of peek-a-boo fun because she has acquired object permanence, which is one of the primary tasks of the sensorimotor stage of cognitive development.
Step-by-step explanation:
Josie finds the game of peek-a-boo fun because she has acquired object permanence, which is one of the primary tasks of the sensorimotor stage of cognitive development according to Piaget. Object permanence is the understanding that even if something is out of sight, it still exists. Infants who have developed object permanence will reach for a hidden toy, indicating their awareness that it still exists.